add ode

1 files changed, 1610 insertions, 0 deletions

diff --git a/libs/ode-0.16.1/ode/src/fastlsolve_impl.h b/libs/ode-0.16.1/ode/src/fastlsolve_impl.h
new file mode 100644
index 0000000..f14ada7
--- /dev/null
+++ b/libs/ode-0.16.1/ode/src/fastlsolve_impl.h
@@ -0,0 +1,1610 @@
+
+
+/*************************************************************************
+ *                                                                       *
+ * Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith.       *
+ * All rights reserved.  Email: russ@q12.org   Web: www.q12.org          *
+ *                                                                       *
+ * This library is free software; you can redistribute it and/or         *
+ * modify it under the terms of EITHER:                                  *
+ *   (1) The GNU Lesser General Public License as published by the Free  *
+ *       Software Foundation; either version 2.1 of the License, or (at  *
+ *       your option) any later version. The text of the GNU Lesser      *
+ *       General Public License is included with this library in the     *
+ *       file LICENSE.TXT.                                               *
+ *   (2) The BSD-style license that is included with this library in     *
+ *       the file LICENSE-BSD.TXT.                                       *
+ *                                                                       *
+ * This library is distributed in the hope that it will be useful,       *
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files    *
+ * LICENSE.TXT and LICENSE-BSD.TXT for more details.                     *
+ *                                                                       *
+ *************************************************************************/
+
+/*
+ * Code style improvements and optimizations by Oleh Derevenko ????-2019
+ * L1Straight cooperative solving code of ThreadedEquationSolverLDLT copyright (c) 2017-2019 Oleh Derevenko, odar@eleks.com (change all "a" to "e")  
+ */
+
+#ifndef _ODE_FASTLSOLVE_IMPL_H_
+#define _ODE_FASTLSOLVE_IMPL_H_
+
+
+/* solve L*X=B, with B containing 1 right hand sides.
+ * L is an n*n lower triangular matrix with ones on the diagonal.
+ * L is stored by rows and its leading dimension is lskip.
+ * B is an n*1 matrix that contains the right hand sides.
+ * B is stored by columns and its leading dimension is also lskip.
+ * B is overwritten with X.
+ * this processes blocks of 4*4.
+ * if this is in the factorizer source file, n must be a multiple of 4.
+ */
+
+template<unsigned int b_stride>
+void solveL1Straight (const dReal *L, dReal *B, unsigned rowCount, unsigned rowSkip)
+{
+    dIASSERT(rowCount != 0);
+
+    /* compute all 4 x 1 blocks of X */
+    unsigned blockStartRow = 0;
+    bool subsequentPass = false;
+    bool goForLoopX4 = rowCount >= 4;
+    const unsigned loopX4LastRow = goForLoopX4 ? rowCount - 4 : 0;
+    for (; goForLoopX4; subsequentPass = true, goForLoopX4 = (blockStartRow += 4) <= loopX4LastRow) 
+    {
+        /* declare variables - Z matrix, p and q vectors, etc */
+        const dReal *ptrLElement;
+        dReal *ptrBElement;
+
+        dReal Z11, Z21, Z31, Z41;
+
+        /* compute all 4 x 1 block of X, from rows i..i+4-1 */
+        if (subsequentPass)
+        {
+            ptrLElement = L + (1 + blockStartRow) * rowSkip;
+            ptrBElement = B;
+            /* set the Z matrix to 0 */
+            Z11 = 0; Z21 = 0; Z31 = 0; Z41 = 0;
+
+            /* the inner loop that computes outer products and adds them to Z */
+            for (unsigned columnCounter = blockStartRow; ; )
+            {
+                dReal q1, p1, p2, p3, p4;
+
+                /* load p and q values */
+                q1 = ptrBElement[0 * b_stride];
+                p1 = (ptrLElement - rowSkip)[0];
+                p2 = ptrLElement[0];
+                ptrLElement += rowSkip;
+                p3 = ptrLElement[0];
+                p4 = ptrLElement[0 + rowSkip];
+
+                /* compute outer product and add it to the Z matrix */
+                Z11 += p1 * q1;
+                Z21 += p2 * q1;
+                Z31 += p3 * q1;
+                Z41 += p4 * q1;
+
+                /* load p and q values */
+                q1 = ptrBElement[1 * b_stride];
+                p3 = ptrLElement[1];
+                p4 = ptrLElement[1 + rowSkip];
+                ptrLElement -= rowSkip;
+                p1 = (ptrLElement - rowSkip)[1];
+                p2 = ptrLElement[1];
+
+                /* compute outer product and add it to the Z matrix */
+                Z11 += p1 * q1;
+                Z21 += p2 * q1;
+                Z31 += p3 * q1;
+                Z41 += p4 * q1;
+
+                /* load p and q values */
+                q1 = ptrBElement[2 * b_stride];
+                p1 = (ptrLElement - rowSkip)[2];
+                p2 = ptrLElement[2];
+                ptrLElement += rowSkip;
+                p3 = ptrLElement[2];
+                p4 = ptrLElement[2 + rowSkip];
+
+                /* compute outer product and add it to the Z matrix */
+                Z11 += p1 * q1;
+                Z21 += p2 * q1;
+                Z31 += p3 * q1;
+                Z41 += p4 * q1;
+
+                /* load p and q values */
+                q1 = ptrBElement[3 * b_stride];
+                p3 = ptrLElement[3];
+                p4 = ptrLElement[3 + rowSkip];
+                ptrLElement -= rowSkip;
+                p1 = (ptrLElement - rowSkip)[3];
+                p2 = ptrLElement[3];
+
+                /* compute outer product and add it to the Z matrix */
+                Z11 += p1 * q1;
+                Z21 += p2 * q1;
+                Z31 += p3 * q1;
+                Z41 += p4 * q1;
+
+                if (columnCounter > 12)
+                {
+                    columnCounter -= 12;
+
+                    /* advance pointers */
+                    ptrLElement += 12;
+                    ptrBElement += 12 * b_stride;
+
+                    /* load p and q values */
+                    q1 = ptrBElement[-8 * (int)b_stride];
+                    p1 = (ptrLElement - rowSkip)[-8];
+                    p2 = ptrLElement[-8];
+                    ptrLElement += rowSkip;
+                    p3 = ptrLElement[-8];
+                    p4 = ptrLElement[-8 + rowSkip];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z21 += p2 * q1;
+                    Z31 += p3 * q1;
+                    Z41 += p4 * q1;
+
+                    /* load p and q values */
+                    q1 = ptrBElement[-7 * (int)b_stride];
+                    p3 = ptrLElement[-7];
+                    p4 = ptrLElement[-7 + rowSkip];
+                    ptrLElement -= rowSkip;
+                    p1 = (ptrLElement - rowSkip)[-7];
+                    p2 = ptrLElement[-7];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z21 += p2 * q1;
+                    Z31 += p3 * q1;
+                    Z41 += p4 * q1;
+
+                    /* load p and q values */
+                    q1 = ptrBElement[-6 * (int)b_stride];
+                    p1 = (ptrLElement - rowSkip)[-6];
+                    p2 = ptrLElement[-6];
+                    ptrLElement += rowSkip;
+                    p3 = ptrLElement[-6];
+                    p4 = ptrLElement[-6 + rowSkip];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z21 += p2 * q1;
+                    Z31 += p3 * q1;
+                    Z41 += p4 * q1;
+
+                    /* load p and q values */
+                    q1 = ptrBElement[-5 * (int)b_stride];
+                    p3 = ptrLElement[-5];
+                    p4 = ptrLElement[-5 + rowSkip];
+                    ptrLElement -= rowSkip;
+                    p1 = (ptrLElement - rowSkip)[-5];
+                    p2 = ptrLElement[-5];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z21 += p2 * q1;
+                    Z31 += p3 * q1;
+                    Z41 += p4 * q1;
+
+                    /* load p and q values */
+                    q1 = ptrBElement[-4 * (int)b_stride];
+                    p1 = (ptrLElement - rowSkip)[-4];
+                    p2 = ptrLElement[-4];
+                    ptrLElement += rowSkip;
+                    p3 = ptrLElement[-4];
+                    p4 = ptrLElement[-4 + rowSkip];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z21 += p2 * q1;
+                    Z31 += p3 * q1;
+                    Z41 += p4 * q1;
+
+                    /* load p and q values */
+                    q1 = ptrBElement[-3 * (int)b_stride];
+                    p3 = ptrLElement[-3];
+                    p4 = ptrLElement[-3 + rowSkip];
+                    ptrLElement -= rowSkip;
+                    p1 = (ptrLElement - rowSkip)[-3];
+                    p2 = ptrLElement[-3];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z21 += p2 * q1;
+                    Z31 += p3 * q1;
+                    Z41 += p4 * q1;
+
+                    /* load p and q values */
+                    q1 = ptrBElement[-2 * (int)b_stride];
+                    p1 = (ptrLElement - rowSkip)[-2];
+                    p2 = ptrLElement[-2];
+                    ptrLElement += rowSkip;
+                    p3 = ptrLElement[-2];
+                    p4 = ptrLElement[-2 + rowSkip];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z21 += p2 * q1;
+                    Z31 += p3 * q1;
+                    Z41 += p4 * q1;
+
+                    /* load p and q values */
+                    q1 = ptrBElement[-1 * (int)b_stride];
+                    p3 = ptrLElement[-1];
+                    p4 = ptrLElement[-1 + rowSkip];
+                    ptrLElement -= rowSkip;
+                    p1 = (ptrLElement - rowSkip)[-1];
+                    p2 = ptrLElement[-1];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z21 += p2 * q1;
+                    Z31 += p3 * q1;
+                    Z41 += p4 * q1;
+                }
+                else
+                {
+                    /* advance pointers */
+                    ptrLElement += 4;
+                    ptrBElement += 4 * b_stride;
+
+                    if ((columnCounter -= 4) == 0)
+                    {
+                        break;
+                    }
+                }
+                /* end of inner loop */
+            }
+        }
+        else
+        {
+            ptrLElement = L + rowSkip/* + blockStartRow * rowSkip*/; dIASSERT(blockStartRow == 0);
+            ptrBElement = B;
+            /* set the Z matrix to 0 */
+            Z11 = 0; Z21 = 0; Z31 = 0; Z41 = 0;
+        }
+
+        /* finish computing the X(i) block */
+        dReal Y11, Y21, Y31, Y41;
+        {
+            Y11 = ptrBElement[0 * b_stride] - Z11;
+            ptrBElement[0 * b_stride] = Y11;
+        }
+        {
+            dReal p2 = ptrLElement[0];
+            Y21 = ptrBElement[1 * b_stride] - Z21 - p2 * Y11;
+            ptrBElement[1 * b_stride] = Y21;
+        }
+        ptrLElement += rowSkip;
+        {
+            dReal p3 = ptrLElement[0];
+            dReal p3_1 = ptrLElement[1];
+            Y31 = ptrBElement[2 * b_stride] - Z31 - p3 * Y11 - p3_1 * Y21;
+            ptrBElement[2 * b_stride] = Y31;
+        }
+        {
+            dReal p4 = ptrLElement[rowSkip];
+            dReal p4_1 = ptrLElement[1 + rowSkip];
+            dReal p4_2 = ptrLElement[2 + rowSkip];
+            Y41 = ptrBElement[3 * b_stride] - Z41 - p4 * Y11 - p4_1 * Y21 - p4_2 * Y31;
+            ptrBElement[3 * b_stride] = Y41;
+        }
+        /* end of outer loop */
+    }
+
+    /* compute rows at end that are not a multiple of block size */
+    for (; !subsequentPass || blockStartRow < rowCount; subsequentPass = true, ++blockStartRow) 
+    {
+        /* compute all 1 x 1 block of X, from rows i..i+1-1 */
+        dReal *ptrBElement;
+
+        dReal Z11, Z12;
+
+        if (subsequentPass)
+        {
+            ptrBElement = B;
+            /* set the Z matrix to 0 */
+            Z11 = 0; Z12 = 0;
+
+            const dReal *ptrLElement = L + blockStartRow * rowSkip;
+
+            /* the inner loop that computes outer products and adds them to Z */
+            unsigned columnCounter = blockStartRow;
+            for (bool exitLoop = columnCounter < 4; !exitLoop; exitLoop = false) 
+            {
+                dReal p1, p2, q1, q2;
+
+                /* load p and q values */
+                p1 = ptrLElement[0];
+                p2 = ptrLElement[1];
+                q1 = ptrBElement[0 * b_stride];
+                q2 = ptrBElement[1 * b_stride];
+
+                /* compute outer product and add it to the Z matrix */
+                Z11 += p1 * q1;
+                Z12 += p2 * q2;
+
+                /* load p and q values */
+                p1 = ptrLElement[2];
+                p2 = ptrLElement[3];
+                q1 = ptrBElement[2 * b_stride];
+                q2 = ptrBElement[3 * b_stride];
+
+                /* compute outer product and add it to the Z matrix */
+                Z11 += p1 * q1;
+                Z12 += p2 * q2;
+
+                if (columnCounter >= (12 + 4))
+                {
+                    columnCounter -= 12;
+
+                    /* advance pointers */
+                    ptrLElement += 12;
+                    ptrBElement += 12 * b_stride;
+
+                    /* load p and q values */
+                    p1 = ptrLElement[-8];
+                    p2 = ptrLElement[-7];
+                    q1 = ptrBElement[-8 * (int)b_stride];
+                    q2 = ptrBElement[-7 * (int)b_stride];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z12 += p2 * q2;
+
+                    /* load p and q values */
+                    p1 = ptrLElement[-6];
+                    p2 = ptrLElement[-5];
+                    q1 = ptrBElement[-6 * (int)b_stride];
+                    q2 = ptrBElement[-5 * (int)b_stride];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z12 += p2 * q2;
+
+                    /* load p and q values */
+                    p1 = ptrLElement[-4];
+                    p2 = ptrLElement[-3];
+                    q1 = ptrBElement[-4 * (int)b_stride];
+                    q2 = ptrBElement[-3 * (int)b_stride];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z12 += p2 * q2;
+
+                    /* load p and q values */
+                    p1 = ptrLElement[-2];
+                    p2 = ptrLElement[-1];
+                    q1 = ptrBElement[-2 * (int)b_stride];
+                    q2 = ptrBElement[-1 * (int)b_stride];
+
+                    /* compute outer product and add it to the Z matrix */
+                    Z11 += p1 * q1;
+                    Z12 += p2 * q2;
+                }
+                else
+                {
+                    /* advance pointers */
+                    ptrLElement += 4;
+                    ptrBElement += 4 * b_stride;
+
+                    if ((columnCounter -= 4) < 4)
+                    {
+                        break;
+                    }
+                }
+                /* end of inner loop */
+            }
+
+            /* compute left-over iterations */
+            if ((columnCounter & 2) != 0) 
+            {
+                dReal p1, p2, q1, q2;
+
+                /* load p and q values */
+                p1 = ptrLElement[0];
+                p2 = ptrLElement[1];
+                q1 = ptrBElement[0 * b_stride];
+                q2 = ptrBElement[1 * b_stride];
+
+                /* compute outer product and add it to the Z matrix */
+                Z11 += p1 * q1;
+                Z12 += p2 * q2;
+
+                /* advance pointers */
+                ptrLElement += 2;
+                ptrBElement += 2 * b_stride;
+            }
+
+            if ((columnCounter & 1) != 0)
+            {
+                dReal p1, q1;
+
+                /* load p and q values */
+                p1 = ptrLElement[0];
+                q1 = ptrBElement[0 * b_stride];
+
+                /* compute outer product and add it to the Z matrix */
+                Z11 += p1 * q1;
+
+                /* advance pointers */
+                // ptrLElement += 1; -- not needed any more
+                ptrBElement += 1 * b_stride;
+            }
+
+            /* finish computing the X(i) block */
+            dReal Y11 = ptrBElement[0 * b_stride] - (Z11 + Z12);
+            ptrBElement[0 * b_stride] = Y11;
+        }
+    }
+}
+
+
+template<unsigned int block_step>
+/*static */
+sizeint ThreadedEquationSolverLDLT::estimateCooperativelySolvingL1StraightMemoryRequirement(unsigned rowCount, SolvingL1StraightMemoryEstimates &ref_solvingMemoryEstimates)
+{
+    unsigned blockCount = deriveSolvingL1StraightBlockCount(rowCount, block_step);
+    sizeint descriptorSizeRequired = dEFFICIENT_SIZE(sizeof(cellindexint) * blockCount);
+    sizeint contextSizeRequired = dEFFICIENT_SIZE(sizeof(SolveL1StraightCellContext) * (CCI__MAX + 1) * blockCount);
+    ref_solvingMemoryEstimates.assignData(descriptorSizeRequired, contextSizeRequired);
+
+    sizeint totalSizeRequired = descriptorSizeRequired + contextSizeRequired;
+    return totalSizeRequired;
+}
+
+template<unsigned int block_step>
+/*static */
+void ThreadedEquationSolverLDLT::initializeCooperativelySolveL1StraightMemoryStructures(unsigned rowCount, 
+    atomicord32 &out_blockCompletionProgress, cellindexint *blockProgressDescriptors, SolveL1StraightCellContext *dUNUSED(cellContexts))
+{
+    unsigned blockCount = deriveSolvingL1StraightBlockCount(rowCount, block_step);
+
+    out_blockCompletionProgress = 0;
+    memset(blockProgressDescriptors, 0, blockCount * sizeof(*blockProgressDescriptors));
+}
+
+template<unsigned int block_step, unsigned int b_stride>
+void ThreadedEquationSolverLDLT::participateSolvingL1Straight(const dReal *L, dReal *B, unsigned rowCount, unsigned rowSkip, 
+    volatile atomicord32 &refBlockCompletionProgress/*=0*/, volatile cellindexint *blockProgressDescriptors/*=[blockCount]*/, 
+    SolveL1StraightCellContext *cellContexts/*=[CCI__MAX x blockCount] + [blockCount]*/, unsigned ownThreadIndex)
+{
+    const unsigned lookaheadRange = 32;
+    const unsigned blockCount = deriveSolvingL1StraightBlockCount(rowCount, block_step), lastBlock = blockCount - 1;
+    /* compute rows at end that are not a multiple of block size */
+    const unsigned loopX1RowCount = rowCount % block_step;
+
+    BlockProcessingState blockProcessingState = BPS_NO_BLOCKS_PROCESSED;
+
+    unsigned completedBlocks = refBlockCompletionProgress;
+    unsigned currentBlock = completedBlocks;
+    dIASSERT(completedBlocks <= blockCount);
+
+    for (bool exitLoop = completedBlocks == blockCount; !exitLoop; exitLoop = false)
+    {
+        bool goForLockedBlockPrimaryCalculation = false, goForLockedBlockDuplicateCalculation = false;
+        bool goAssigningTheResult = false, stayWithinTheBlock = false;
+
+        dReal Z[block_step];
+        dReal Y[block_step];
+
+        dReal *ptrBElement;
+
+        CellContextInstance previousContextInstance;
+        unsigned completedColumnBlock;
+        bool partialBlock;
+
+        for (cellindexint testDescriptor = blockProgressDescriptors[currentBlock]; ; )
+        {
+            if (testDescriptor == INVALID_CELLDESCRIPTOR)
+            {
+                // Invalid descriptor is the indication that the row has been fully calculated
+                // Test if this was the last row and break out if so.
+                if (currentBlock + 1 == blockCount)
+                {
+                    exitLoop = true;
+                    break;
+                }
+
+                // Treat detected row advancement as a row processed
+                // blockProcessingState = BPS_SOME_BLOCKS_PROCESSED; <-- performs better without it
+                break;
+            }
+
+            CooperativeAtomics::AtomicReadReorderBarrier();
+            // It is necessary to read up to date completedBblocks value after the descriptor retrieval
+            // as otherwise the logic below breaks
+            completedBlocks = refBlockCompletionProgress;
+
+            if (!GET_CELLDESCRIPTOR_ISLOCKED(testDescriptor))
+            {
+                completedColumnBlock = GET_CELLDESCRIPTOR_COLUMNINDEX(testDescriptor);
+                dIASSERT(completedColumnBlock < currentBlock || (completedColumnBlock == currentBlock && currentBlock == 0)); // Otherwise, why would the calculation have had stopped if the final column is reachable???
+                dIASSERT(completedColumnBlock <= completedBlocks); // Since the descriptor is not locked
+
+                if (completedColumnBlock == completedBlocks && currentBlock != completedBlocks)
+                {
+                    dIASSERT(completedBlocks < currentBlock);
+                    break;
+                }
+
+                if (CooperativeAtomics::AtomicCompareExchangeCellindexint(&blockProgressDescriptors[currentBlock], testDescriptor, MARK_CELLDESCRIPTOR_LOCKED(testDescriptor)))
+                {
+                    if (completedColumnBlock != 0)
+                    {
+                        CellContextInstance contextInstance = GET_CELLDESCRIPTOR_CONTEXTINSTANCE(testDescriptor);
+                        previousContextInstance = contextInstance;
+
+                        const SolveL1StraightCellContext &sourceContext = buildBlockContextRef(cellContexts, currentBlock, contextInstance);
+                        sourceContext.loadPrecalculatedZs(Z);
+                    }
+                    else
+                    {
+                        previousContextInstance = CCI__MIN;
+                        SolveL1StraightCellContext::initializePrecalculatedZs(Z);
+                    }
+
+                    goForLockedBlockPrimaryCalculation = true;
+                    break;
+                }
+
+                if (blockProcessingState != BPS_COMPETING_FOR_A_BLOCK)
+                {
+                    break;
+                }
+
+                testDescriptor = blockProgressDescriptors[currentBlock];
+            }
+            else
+            {
+                if (blockProcessingState != BPS_COMPETING_FOR_A_BLOCK)
+                {
+                    break;
+                }
+
+                cellindexint verificativeDescriptor;
+                bool verificationFailure = false;
+
+                completedColumnBlock = GET_CELLDESCRIPTOR_COLUMNINDEX(testDescriptor);
+                dIASSERT(completedColumnBlock != currentBlock || currentBlock == 0); // There is no reason for computations to stop at the very end other than being the initial value at the very first block
+
+                if (completedColumnBlock != 0)
+                {
+                    CellContextInstance contextInstance = GET_CELLDESCRIPTOR_CONTEXTINSTANCE(testDescriptor);
+                    const SolveL1StraightCellContext &sourceContext = buildBlockContextRef(cellContexts, currentBlock, contextInstance);
+                    sourceContext.loadPrecalculatedZs(Z);
+                }
+                else
+                {
+                    SolveL1StraightCellContext::initializePrecalculatedZs(Z);
+                }
+
+                if (completedColumnBlock != 0 && completedColumnBlock <= currentBlock)
+                {
+                    // Make sure the descriptor is re-read after the precalculates
+                    CooperativeAtomics::AtomicReadReorderBarrier();
+                }
+
+                if (completedColumnBlock <= currentBlock)
+                {
+                    verificativeDescriptor = blockProgressDescriptors[currentBlock];
+                    verificationFailure = verificativeDescriptor != testDescriptor;
+                }
+
+                if (!verificationFailure)
+                {
+                    dIASSERT(completedColumnBlock <= currentBlock + 1);
+
+                    goForLockedBlockDuplicateCalculation = true;
+                    break;
+                }
+
+                testDescriptor = verificativeDescriptor;
+            }
+        }
+
+        if (exitLoop)
+        {
+            break;
+        }
+
+        if (goForLockedBlockPrimaryCalculation)
+        {
+            blockProcessingState = BPS_SOME_BLOCKS_PROCESSED;
+
+            // Declare and assign the variables at the top to not interfere with any branching -- the compiler is going to eliminate them anyway.
+            bool handleComputationTakenOver = false, rowEndReached = false;
+
+            const dReal *ptrLElement;
+            unsigned finalColumnBlock;
+
+            /* check if this is not the partial block of fewer rows */
+            if (currentBlock != lastBlock || loopX1RowCount == 0)
+            {
+                partialBlock = false;
+
+                if (currentBlock != 0)
+                {
+                    ptrLElement = L + (sizeint)(1 + currentBlock * block_step) * rowSkip + completedColumnBlock * block_step;
+                    ptrBElement = B + (sizeint)(completedColumnBlock * block_step) * b_stride;
+
+                    /* the inner loop that computes outer products and adds them to Z */
+                    finalColumnBlock = dMACRO_MIN(currentBlock, completedBlocks);
+                    dIASSERT(completedColumnBlock != finalColumnBlock/* || currentBlock == 0*/);
+
+                    for (unsigned columnCounter = finalColumnBlock - completedColumnBlock; ; )
+                    {
+                        dReal q1, p1, p2, p3, p4;
+
+                        /* load p and q values */
+                        q1 = ptrBElement[0 * b_stride];
+                        p1 = (ptrLElement - rowSkip)[0];
+                        p2 = ptrLElement[0];
+                        ptrLElement += rowSkip;
+                        p3 = ptrLElement[0];
+                        p4 = ptrLElement[0 + rowSkip];
+
+                        /* compute outer product and add it to the Z matrix */
+                        Z[0] += p1 * q1;
+                        Z[1] += p2 * q1;
+                        Z[2] += p3 * q1;
+                        Z[3] += p4 * q1;
+
+                        /* load p and q values */
+                        q1 = ptrBElement[1 * b_stride];
+                        p3 = ptrLElement[1];
+                        p4 = ptrLElement[1 + rowSkip];
+                        ptrLElement -= rowSkip;
+                        p1 = (ptrLElement - rowSkip)[1];
+                        p2 = ptrLElement[1];
+
+                        /* compute outer product and add it to the Z matrix */
+                        Z[0] += p1 * q1;
+                        Z[1] += p2 * q1;
+                        Z[2] += p3 * q1;
+                        Z[3] += p4 * q1;
+
+                        /* load p and q values */
+                        q1 = ptrBElement[2 * b_stride];
+                        p1 = (ptrLElement - rowSkip)[2];
+                        p2 = ptrLElement[2];
+                        ptrLElement += rowSkip;
+                        p3 = ptrLElement[2];
+                        p4 = ptrLElement[2 + rowSkip];
+
+                        /* compute outer product and add it to the Z matrix */
+                        Z[0] += p1 * q1;
+                        Z[1] += p2 * q1;
+                        Z[2] += p3 * q1;
+                        Z[3] += p4 * q1;
+
+                        /* load p and q values */
+                        q1 = ptrBElement[3 * b_stride];
+                        p3 = ptrLElement[3];
+                        p4 = ptrLElement[3 + rowSkip];
+                        ptrLElement -= rowSkip;
+                        p1 = (ptrLElement - rowSkip)[3];
+                        p2 = ptrLElement[3];
+
+                        /* compute outer product and add it to the Z matrix */
+                        Z[0] += p1 * q1;
+                        Z[1] += p2 * q1;
+                        Z[2] += p3 * q1;
+                        Z[3] += p4 * q1;
+                        dSASSERT(block_step == 4);
+
+                        if (columnCounter > 3)
+                        {
+                            columnCounter -= 3;
+
+                            ptrLElement += 3 * block_step;
+                            ptrBElement += 3 * block_step * b_stride;
+
+                            /* load p and q values */
+                            q1 = ptrBElement[-8 * (int)b_stride];
+                            p1 = (ptrLElement - rowSkip)[-8];
+                            p2 = ptrLElement[-8];
+                            ptrLElement += rowSkip;
+                            p3 = ptrLElement[-8];
+                            p4 = ptrLElement[-8 + rowSkip];
+
+                            /* compute outer product and add it to the Z matrix */
+                            Z[0] += p1 * q1;
+                            Z[1] += p2 * q1;
+                            Z[2] += p3 * q1;
+                            Z[3] += p4 * q1;
+
+                            /* load p and q values */
+                            q1 = ptrBElement[-7 * (int)b_stride];
+                            p3 = ptrLElement[-7];
+                            p4 = ptrLElement[-7 + rowSkip];
+                            ptrLElement -= rowSkip;
+                            p1 = (ptrLElement - rowSkip)[-7];
+                            p2 = ptrLElement[-7];
+
+                            /* compute outer product and add it to the Z matrix */
+                            Z[0] += p1 * q1;
+                            Z[1] += p2 * q1;
+                            Z[2] += p3 * q1;
+                            Z[3] += p4 * q1;
+
+                            /* load p and q values */
+                            q1 = ptrBElement[-6 * (int)b_stride];
+                            p1 = (ptrLElement - rowSkip)[-6];
+                            p2 = ptrLElement[-6];
+                            ptrLElement += rowSkip;
+                            p3 = ptrLElement[-6];
+                            p4 = ptrLElement[-6 + rowSkip];
+
+                            /* compute outer product and add it to the Z matrix */
+                            Z[0] += p1 * q1;
+                            Z[1] += p2 * q1;
+                            Z[2] += p3 * q1;
+                            Z[3] += p4 * q1;
+
+                            /* load p and q values */
+                            q1 = ptrBElement[-5 * (int)b_stride];
+                            p3 = ptrLElement[-5];
+                            p4 = ptrLElement[-5 + rowSkip];
+                            ptrLElement -= rowSkip;
+                            p1 = (ptrLElement - rowSkip)[-5];
+                            p2 = ptrLElement[-5];
+
+                            /* compute outer product and add it to the Z matrix */
+                            Z[0] += p1 * q1;
+                            Z[1] += p2 * q1;
+                            Z[2] += p3 * q1;
+                            Z[3] += p4 * q1;
+
+                            /* load p and q values */
+                            q1 = ptrBElement[-4 * (int)b_stride];
+                            p1 = (ptrLElement - rowSkip)[-4];
+                            p2 = ptrLElement[-4];
+                            ptrLElement += rowSkip;
+                            p3 = ptrLElement[-4];
+                            p4 = ptrLElement[-4 + rowSkip];
+
+                            /* compute outer product and add it to the Z matrix */
+                            Z[0] += p1 * q1;
+                            Z[1] += p2 * q1;
+                            Z[2] += p3 * q1;
+                            Z[3] += p4 * q1;
+
+                            /* load p and q values */
+                            q1 = ptrBElement[-3 * (int)b_stride];
+                            p3 = ptrLElement[-3];
+                            p4 = ptrLElement[-3 + rowSkip];
+                            ptrLElement -= rowSkip;
+                            p1 = (ptrLElement - rowSkip)[-3];
+                            p2 = ptrLElement[-3];
+
+                            /* compute outer product and add it to the Z matrix */
+                            Z[0] += p1 * q1;
+                            Z[1] += p2 * q1;
+                            Z[2] += p3 * q1;
+                            Z[3] += p4 * q1;
+
+                            /* load p and q values */
+                            q1 = ptrBElement[-2 * (int)b_stride];
+                            p1 = (ptrLElement - rowSkip)[-2];
+                            p2 = ptrLElement[-2];
+                            ptrLElement += rowSkip;
+                            p3 = ptrLElement[-2];
+                            p4 = ptrLElement[-2 + rowSkip];
+
+                            /* compute outer product and add it to the Z matrix */
+                            Z[0] += p1 * q1;
+                            Z[1] += p2 * q1;
+                            Z[2] += p3 * q1;
+                            Z[3] += p4 * q1;
+
+                            /* load p and q values */
+                            q1 = ptrBElement[-1 * (int)b_stride];
+                            p3 = ptrLElement[-1];
+                            p4 = ptrLElement[-1 + rowSkip];
+                            ptrLElement -= rowSkip;
+                            p1 = (ptrLElement - rowSkip)[-1];
+                            p2 = ptrLElement[-1];
+
+                            /* compute outer product and add it to the Z matrix */
+                            Z[0] += p1 * q1;
+                            Z[1] += p2 * q1;
+                            Z[2] += p3 * q1;
+                            Z[3] += p4 * q1;
+                            dSASSERT(block_step == 4);
+                        }
+                        else
+                        {
+                            ptrLElement += block_step;
+                            ptrBElement += block_step * b_stride;
+
+                            if (--columnCounter == 0)
+                            {
+                                if (finalColumnBlock == currentBlock)
+                                {
+                                    rowEndReached = true;
+                                    break;
+                                }
+
+                                // Take a look if any more columns have been completed...
+                                completedBlocks = refBlockCompletionProgress;
+                                dIASSERT(completedBlocks >= finalColumnBlock);
+
+                                if (completedBlocks == finalColumnBlock)
+                                {
+                                    break;
+                                }
+
+                                // ...continue if so.
+                                unsigned columnCompletedSoFar = finalColumnBlock;
+                                finalColumnBlock = dMACRO_MIN(currentBlock, completedBlocks);
+                                columnCounter = finalColumnBlock - columnCompletedSoFar;
+                            }
+                        }
+                        /* end of inner loop */
+                    }
+                }
+                else
+                {
+                    ptrLElement = L + (sizeint)(1/* + currentBlock * block_step*/) * rowSkip/* + completedColumnBlock * block_step*/;
+                    ptrBElement = B/* + (sizeint)(completedColumnBlock * block_step) * b_stride*/;
+                    dIASSERT(completedColumnBlock == 0);
+
+                    rowEndReached = true;
+                }
+            }
+            else
+            {
+                partialBlock = true;
+
+                if (currentBlock != 0)
+                {
+                    dReal tempZ[dMACRO_MAX(block_step - 1U, 1U)] = { REAL(0.0), };
+
+                    ptrLElement = L + (sizeint)(/*1 + */currentBlock * block_step) * rowSkip + completedColumnBlock * block_step;
+                    ptrBElement = B + (sizeint)(completedColumnBlock * block_step) * b_stride;
+
+                    /* the inner loop that computes outer products and adds them to Z */
+                    finalColumnBlock = dMACRO_MIN(currentBlock, completedBlocks);
+                    dIASSERT(completedColumnBlock != finalColumnBlock/* || currentBlock == 0*/);
+
+                    for (unsigned partialRow = 0, columnCompletedSoFar = completedColumnBlock; ; )
+                    {
+                        dReal Z1 = 0, Z2 = 0, Z3 = 0, Z4 = 0;
+
+                        for (unsigned columnCounter = finalColumnBlock - columnCompletedSoFar; ; )
+                        {
+                            dReal q1, q2, q3, q4, p1, p2, p3, p4;
+
+                            /* load p and q values */
+                            q1 = ptrBElement[0 * b_stride];
+                            q2 = ptrBElement[1 * b_stride];
+                            q3 = ptrBElement[2 * b_stride];
+                            q4 = ptrBElement[3 * b_stride];
+                            p1 = ptrLElement[0];
+                            p2 = ptrLElement[1];
+                            p3 = ptrLElement[2];
+                            p4 = ptrLElement[3];
+
+                            /* compute outer product and add it to the Z matrix */
+                            Z1 += p1 * q1;
+                            Z2 += p2 * q2;
+                            Z3 += p3 * q3;
+                            Z4 += p4 * q4;
+                            dSASSERT(block_step == 4);
+
+                            if (columnCounter > 3)
+                            {
+                                columnCounter -= 3;
+
+                                ptrLElement += 3 * block_step;
+                                ptrBElement += 3 * block_step * b_stride;
+                            
+                                /* load p and q values */
+                                q1 = ptrBElement[-8 * (int)b_stride];
+                                q2 = ptrBElement[-7 * (int)b_stride];
+                                q3 = ptrBElement[-6 * (int)b_stride];
+                                q4 = ptrBElement[-5 * (int)b_stride];
+                                p1 = ptrLElement[-8];
+                                p2 = ptrLElement[-7];
+                                p3 = ptrLElement[-6];
+                                p4 = ptrLElement[-5];
+
+                                /* compute outer product and add it to the Z matrix */
+                                Z1 += p1 * q1;
+                                Z2 += p2 * q2;
+                                Z3 += p3 * q3;
+                                Z4 += p4 * q4;
+
+                                /* load p and q values */
+                                q1 = ptrBElement[-4 * (int)b_stride];
+                                q2 = ptrBElement[-3 * (int)b_stride];
+                                q3 = ptrBElement[-2 * (int)b_stride];
+                                q4 = ptrBElement[-1 * (int)b_stride];
+                                p1 = ptrLElement[-4];
+                                p2 = ptrLElement[-3];
+                                p3 = ptrLElement[-2];
+                                p4 = ptrLElement[-1];
+
+                                /* compute outer product and add it to the Z matrix */
+                                Z1 += p1 * q1;
+                                Z2 += p2 * q2;
+                                Z3 += p3 * q3;
+                                Z4 += p4 * q4;
+                                dSASSERT(block_step == 4);
+                            }
+                            else
+                            {
+                                ptrLElement += block_step;
+                                ptrBElement += block_step * b_stride;
+
+                                if (--columnCounter == 0)
+                                {
+                                    break;
+                                }
+                            }
+                            /* end of inner loop */
+                        }
+
+                        tempZ[partialRow] += Z1 + Z2 + Z3 + Z4;
+
+                        if (++partialRow == loopX1RowCount)
+                        {
+                            // Here switch is used to avoid accessing Z by parametrized index. 
+                            // So far all the accesses were performed by explicit constants
+                            // what lets the compiler treat Z elements as individual variables 
+                            // rather than array elements.
+                            Z[0] += tempZ[0];
+
+                            if (loopX1RowCount >= 2)
+                            {
+                                Z[1] += tempZ[1];
+
+                                if (loopX1RowCount > 2)
+                                {
+                                    Z[2] += tempZ[2];
+                                }
+                            }
+                            dSASSERT(block_step == 4);
+
+                            if (finalColumnBlock == currentBlock)
+                            {
+                                if (loopX1RowCount > 2)
+                                {
+                                    // Correct the LElement so that it points to the second row
+                                    //
+                                    // Note, that ff there is just one partial row, it does not matter that 
+                                    // the LElement will remain pointing at the first row, 
+                                    // since the former is not going to be used in that case.
+                                    ptrLElement -= /*(sizeint)*/rowSkip/* * (loopX1RowCount - 2)*/; dIASSERT(loopX1RowCount == 3);
+                                }
+                                dSASSERT(block_step == 4);
+
+                                rowEndReached = true;
+                                break;
+                            }
+
+                            // Take a look if any more columns have been completed...
+                            completedBlocks = refBlockCompletionProgress;
+                            dIASSERT(completedBlocks >= finalColumnBlock);
+
+                            if (completedBlocks == finalColumnBlock)
+                            {
+                                break;
+                            }
+
+                            std::fill(tempZ, tempZ + loopX1RowCount, REAL(0.0));
+                            partialRow = 0;
+
+                            // Correct the LElement pointer to continue at the first partial row
+                            ptrLElement -= (sizeint)rowSkip * (loopX1RowCount - 1);
+
+                            // ...continue if so.
+                            columnCompletedSoFar = finalColumnBlock;
+                            finalColumnBlock = dMACRO_MIN(currentBlock, completedBlocks);
+                        }
+                        else
+                        {
+                            ptrLElement += rowSkip - (finalColumnBlock - columnCompletedSoFar) * block_step;
+                            ptrBElement -= (sizeint)((finalColumnBlock - columnCompletedSoFar) * block_step) * b_stride;
+                        }
+                        /* end of loop by individual rows */
+                    }
+                }
+                else
+                {
+                    ptrLElement = L + (sizeint)(1/* + currentBlock * block_step*/) * rowSkip/* + completedColumnBlock * block_step*/;
+                    ptrBElement = B/* + (sizeint)(completedColumnBlock * block_step) * b_stride*/;
+                    dIASSERT(completedColumnBlock == 0);
+
+                    rowEndReached = true;
+                }
+            }
+
+            if (rowEndReached)
+            {
+                // Check whether there is still a need to proceed or if the computation has been taken over by another thread
+                cellindexint oldDescriptor = MAKE_CELLDESCRIPTOR(completedColumnBlock, previousContextInstance, true);
+
+                if (blockProgressDescriptors[currentBlock] == oldDescriptor)
+                {
+                    /* finish computing the X(i) block */
+                    if (!partialBlock)
+                    {
+                        Y[0] = ptrBElement[0 * b_stride] - Z[0];
+
+                        dReal p2 = ptrLElement[0];
+                        Y[1] = ptrBElement[1 * b_stride] - Z[1] - p2 * Y[0];
+
+                        ptrLElement += rowSkip;
+
+                        dReal p3 = ptrLElement[0];
+                        dReal p3_1 = ptrLElement[1];
+                        Y[2] = ptrBElement[2 * b_stride] - Z[2] - p3 * Y[0] - p3_1 * Y[1];
+
+                        dReal p4 = ptrLElement[rowSkip];
+                        dReal p4_1 = ptrLElement[1 + rowSkip];
+                        dReal p4_2 = ptrLElement[2 + rowSkip];
+                        Y[3] = ptrBElement[3 * b_stride] - Z[3] - p4 * Y[0] - p4_1 * Y[1] - p4_2 * Y[2];
+                        dSASSERT(block_step == 4);
+                    }
+                    else
+                    {
+                        Y[0] = ptrBElement[0 * b_stride] - Z[0];
+
+                        if (loopX1RowCount >= 2)
+                        {
+                            dReal p2 = ptrLElement[0];
+                            Y[1] = ptrBElement[1 * b_stride] - Z[1] - p2 * Y[0];
+
+                            if (loopX1RowCount > 2)
+                            {
+                                dReal p3 = ptrLElement[0 + rowSkip];
+                                dReal p3_1 = ptrLElement[1 + rowSkip];
+                                Y[2] = ptrBElement[2 * b_stride] - Z[2] - p3 * Y[0] - p3_1 * Y[1];
+                            }
+                        }
+                        dSASSERT(block_step == 4);
+                    }
+
+                    // Use atomic memory barrier to make sure memory reads of ptrBElement[] and blockProgressDescriptors[] are not swapped
+                    CooperativeAtomics::AtomicReadReorderBarrier();
+
+                    // The descriptor has not been altered yet - this means the ptrBElement[] values used above were not modified yet 
+                    // and the computation result is valid.
+                    if (blockProgressDescriptors[currentBlock] == oldDescriptor)
+                    {
+                        // Assign the results to the result context (possibly in parallel with other threads 
+                        // that could and ought to be assigning exactly the same values)
+                        SolveL1StraightCellContext &resultContext = buildResultContextRef(cellContexts, currentBlock, blockCount);
+                        resultContext.storePrecalculatedZs(Y);
+
+                        // Assign the result assignment progress descriptor
+                        cellindexint newDescriptor = MAKE_CELLDESCRIPTOR(currentBlock + 1, CCI__MIN, true);
+                        CooperativeAtomics::AtomicCompareExchangeCellindexint(&blockProgressDescriptors[currentBlock], oldDescriptor, newDescriptor); // the result is to be ignored
+
+                        // Whether succeeded or not, the result is valid, so go on trying to assign it to the matrix
+                        goAssigningTheResult = true;
+                    }
+                    else
+                    {
+                        // Otherwise, go on competing for copying the results
+                        handleComputationTakenOver = true;
+                    }
+                }
+                else
+                {
+                    handleComputationTakenOver = true;
+                }
+            }
+            else
+            {
+                // If the final column has not been reached yet, store current values to the context.
+                // Select the other context instance as the previous one might be read by other threads.
+                CellContextInstance nextContextInstance = buildNextContextInstance(previousContextInstance);
+                SolveL1StraightCellContext &destinationContext = buildBlockContextRef(cellContexts, currentBlock, nextContextInstance);
+                destinationContext.storePrecalculatedZs(Z);
+
+                // Unlock the row until more columns can be used
+                cellindexint oldDescriptor = MAKE_CELLDESCRIPTOR(completedColumnBlock, previousContextInstance, true);
+                cellindexint newDescriptor = MAKE_CELLDESCRIPTOR(finalColumnBlock, nextContextInstance, false);
+                // The descriptor might have been updated by a competing thread
+                if (!CooperativeAtomics::AtomicCompareExchangeCellindexint(&blockProgressDescriptors[currentBlock], oldDescriptor, newDescriptor))
+                {
+                    // Adjust the ptrBElement to point to the result area...
+                    ptrBElement = B + (sizeint)(currentBlock * block_step) * b_stride;
+                    // ...and go on handling the case
+                    handleComputationTakenOver = true;
+                }
+            }
+
+            if (handleComputationTakenOver)
+            {
+                cellindexint existingDescriptor = blockProgressDescriptors[currentBlock];
+                // This can only happen if the row was (has become) the uppermost not fully completed one
+                // and the competing thread is at final stage of calculation (i.e., it has reached the currentBlock column).
+                if (existingDescriptor != INVALID_CELLDESCRIPTOR)
+                {
+                    // If not fully completed this must be the final stage of the result assignment into the matrix
+                    dIASSERT(existingDescriptor == MAKE_CELLDESCRIPTOR(currentBlock + 1, CCI__MIN, true));
+
+                    // Go on competing copying the result as anyway the block is the topmost not completed one
+                    // and since there was competition for it, there is no other work that can be done right now.
+                    const SolveL1StraightCellContext &resultContext = buildResultContextRef(cellContexts, currentBlock, blockCount);
+                    resultContext.loadPrecalculatedZs(Y);
+
+                    goAssigningTheResult = true;
+                }
+                else 
+                {
+                    // everything is over -- just go handling next blocks
+                }
+            }
+        }
+        else if (goForLockedBlockDuplicateCalculation)
+        {
+            blockProcessingState = BPS_SOME_BLOCKS_PROCESSED;
+
+            bool skipToHandlingSubsequentRows = false, skiptoCopyingResult = false;
+
+            /* declare variables */
+            const dReal *ptrLElement;
+
+            if (completedColumnBlock < currentBlock)
+            {
+                /* check if this is not the partial block of fewer rows */
+                if (currentBlock != lastBlock || loopX1RowCount == 0)
+                {
+                    partialBlock = false;
+
+                    ptrLElement = L + (sizeint)(1 + currentBlock * block_step) * rowSkip + completedColumnBlock * block_step;
+                    ptrBElement = B + (sizeint)(completedColumnBlock * block_step) * b_stride;
+
+                    /* the inner loop that computes outer products and adds them to Z */
+                    unsigned finalColumnBlock = currentBlock;
+                    dIASSERT(currentBlock == completedBlocks); // Why would we be competing for a row otherwise?
+
+                    unsigned lastCompletedColumn = completedColumnBlock;
+                    unsigned columnCounter = finalColumnBlock - completedColumnBlock;
+                    for (bool exitInnerLoop = false; !exitInnerLoop; exitInnerLoop = --columnCounter == 0)
+                    {
+                        dReal q1, p1, p2, p3, p4;
+
+                        /* load p and q values */
+                        q1 = ptrBElement[0 * b_stride];
+                        p1 = (ptrLElement - rowSkip)[0];
+                        p2 = ptrLElement[0];
+                        ptrLElement += rowSkip;
+                        p3 = ptrLElement[0];
+                        p4 = ptrLElement[0 + rowSkip];
+
+                        /* compute outer product and add it to the Z matrix */
+                        Z[0] += p1 * q1;
+                        Z[1] += p2 * q1;
+                        Z[2] += p3 * q1;
+                        Z[3] += p4 * q1;
+
+                        /* load p and q values */
+                        q1 = ptrBElement[1 * b_stride];
+                        p3 = ptrLElement[1];
+                        p4 = ptrLElement[1 + rowSkip];
+                        ptrLElement -= rowSkip;
+                        p1 = (ptrLElement - rowSkip)[1];
+                        p2 = ptrLElement[1];
+
+                        /* compute outer product and add it to the Z matrix */
+                        Z[0] += p1 * q1;
+                        Z[1] += p2 * q1;
+                        Z[2] += p3 * q1;
+                        Z[3] += p4 * q1;
+
+                        /* load p and q values */
+                        q1 = ptrBElement[2 * b_stride];
+                        p1 = (ptrLElement - rowSkip)[2];
+                        p2 = ptrLElement[2];
+                        ptrLElement += rowSkip;
+                        p3 = ptrLElement[2];
+                        p4 = ptrLElement[2 + rowSkip];
+
+                        /* compute outer product and add it to the Z matrix */
+                        Z[0] += p1 * q1;
+                        Z[1] += p2 * q1;
+                        Z[2] += p3 * q1;
+                        Z[3] += p4 * q1;
+
+                        /* load p and q values */
+                        q1 = ptrBElement[3 * b_stride];
+                        p3 = ptrLElement[3];
+                        p4 = ptrLElement[3 + rowSkip];
+                        ptrLElement -= rowSkip;
+                        p1 = (ptrLElement - rowSkip)[3];
+                        p2 = ptrLElement[3];
+
+                        /* compute outer product and add it to the Z matrix */
+                        Z[0] += p1 * q1;
+                        Z[1] += p2 * q1;
+                        Z[2] += p3 * q1;
+                        Z[3] += p4 * q1;
+                        dSASSERT(block_step == 4);
+
+                        // Check if the primary solver thread has not made any progress
+                        cellindexint descriptorVerification = blockProgressDescriptors[currentBlock];
+                        unsigned newCompletedColumn = GET_CELLDESCRIPTOR_COLUMNINDEX(descriptorVerification);
+
+                        if (newCompletedColumn != lastCompletedColumn)
+                        {
+                            // Check, this is the first change the current thread detects.
+                            // There is absolutely no reason in code for the computation to stop/resume twice 
+                            // while the current thread is competing.
+                            dIASSERT(lastCompletedColumn == completedColumnBlock);
+
+                            if (descriptorVerification == INVALID_CELLDESCRIPTOR)
+                            {
+                                skipToHandlingSubsequentRows = true;
+                                break;
+                            }
+
+                            if (newCompletedColumn == currentBlock + 1)
+                            {
+                                skiptoCopyingResult = true;
+                                break;
+                            }
+
+                            // Check if the current thread is behind
+                            if (newCompletedColumn > finalColumnBlock - columnCounter)
+                            {
+                                // If so, go starting over one more time
+                                blockProcessingState = BPS_COMPETING_FOR_A_BLOCK;
+                                stayWithinTheBlock = true;
+                                skipToHandlingSubsequentRows = true;
+                                break;
+                            }
+
+                            // If current thread is ahead, just save new completed column for further comparisons and go on calculating
+                            lastCompletedColumn = newCompletedColumn;
+                        }
+
+                        /* advance pointers */
+                        ptrLElement += block_step;
+                        ptrBElement += block_step * b_stride;
+                        /* end of inner loop */
+                    }
+                }
+                else
+                {
+                    partialBlock = true;
+
+                    dReal tempZ[dMACRO_MAX(block_step - 1U, 1U)] = { REAL(0.0), };
+
+                    ptrLElement = L + (sizeint)(/*1 + */currentBlock * block_step) * rowSkip + completedColumnBlock * block_step;
+                    ptrBElement = B + (sizeint)(completedColumnBlock * block_step) * b_stride;
+
+                    /* the inner loop that computes outer products and adds them to Z */
+                    unsigned finalColumnBlock = currentBlock;
+                    dIASSERT(currentBlock == completedBlocks); // Why would we be competing for a row otherwise?
+
+                    unsigned lastCompletedColumn = completedColumnBlock;
+                    for (unsigned columnCounter = finalColumnBlock - completedColumnBlock; ; )
+                    {
+                        dReal q1, q2, q3, q4;
+
+                        /* load q values */
+                        q1 = ptrBElement[0 * b_stride];
+                        q2 = ptrBElement[1 * b_stride];
+                        q3 = ptrBElement[2 * b_stride];
+                        q4 = ptrBElement[3 * b_stride];
+
+                        for (unsigned partialRow = 0; ; )
+                        {
+                            dReal p1, p2, p3, p4;
+
+                            /* load p values */
+                            p1 = ptrLElement[0];
+                            p2 = ptrLElement[1];
+                            p3 = ptrLElement[2];
+                            p4 = ptrLElement[3];
+
+                            /* compute outer product and add it to the Z matrix */
+                            tempZ[partialRow] += p1 * q1 + p2 * q2 + p3 * q3 + p4 * q4;
+                            dSASSERT(block_step == 4);
+
+                            if (++partialRow == loopX1RowCount)
+                            {
+                                break;
+                            }
+
+                            ptrLElement += rowSkip;
+                        }
+
+                        // Check if the primary solver thread has not made any progress
+                        cellindexint descriptorVerification = blockProgressDescriptors[currentBlock];
+                        unsigned newCompletedColumn = GET_CELLDESCRIPTOR_COLUMNINDEX(descriptorVerification);
+
+                        if (newCompletedColumn != lastCompletedColumn)
+                        {
+                            // Check, this is the first change the current thread detects.
+                            // There is absolutely no reason in code for the computation to stop/resume twice 
+                            // while the current thread is competing.
+                            dIASSERT(lastCompletedColumn == completedColumnBlock);
+
+                            if (descriptorVerification == INVALID_CELLDESCRIPTOR)
+                            {
+                                skipToHandlingSubsequentRows = true;
+                                break;
+                            }
+
+                            if (newCompletedColumn == currentBlock + 1)
+                            {
+                                skiptoCopyingResult = true;
+                                break;
+                            }
+
+                            // Check if the current thread is behind
+                            if (newCompletedColumn > finalColumnBlock - columnCounter)
+                            {
+                                // If so, go starting over one more time
+                                blockProcessingState = BPS_COMPETING_FOR_A_BLOCK;
+                                stayWithinTheBlock = true;
+                                skipToHandlingSubsequentRows = true;
+                                break;
+                            }
+
+                            // If current thread is ahead, just save new completed column for further comparisons and go on calculating
+                            lastCompletedColumn = newCompletedColumn;
+                        }
+
+                        ptrLElement += block_step;
+                        ptrBElement += block_step * b_stride;
+
+                        if (--columnCounter == 0)
+                        {
+                            // Here switch is used to avoid accessing Z by parametrized index. 
+                            // So far all the accesses were performed by explicit constants
+                            // what lets the compiler treat Z elements as individual variables 
+                            // rather than array elements.
+                            Z[0] += tempZ[0];
+
+                            if (loopX1RowCount >= 2)
+                            {
+                                Z[1] += tempZ[1];
+
+                                if (loopX1RowCount > 2)
+                                {
+                                    Z[2] += tempZ[2];
+
+                                    // Correct the LElement so that it points to the second row
+                                    //
+                                    // Note, that if there is just one partial row, it does not matter that 
+                                    // the LElement will remain pointing at the first row, 
+                                    // since the former is not going to be used in that case.
+                                    ptrLElement -= /*(sizeint)*/rowSkip/* * (loopX1RowCount - 2)*/; dIASSERT(loopX1RowCount == 3);
+                                }
+                            }
+                            dSASSERT(block_step == 4);
+
+                            break;
+                        }
+
+                        /* advance pointers */
+                        ptrLElement -= (sizeint)rowSkip * (loopX1RowCount - 1);
+                        /* end of inner loop */
+                    }
+                }
+            }
+            else if (completedColumnBlock > currentBlock)
+            {
+                dIASSERT(completedColumnBlock == currentBlock + 1);
+
+                partialBlock = currentBlock == lastBlock && loopX1RowCount != 0;
+
+                skiptoCopyingResult = true;
+            }
+            else
+            {
+                dIASSERT(currentBlock == 0); // Execution can get here within the very first block only
+
+                partialBlock = rowCount < block_step;
+
+                /* assign the pointers appropriately and go on computing the results */
+                ptrLElement = L + (sizeint)(1/* + currentBlock * block_step*/) * rowSkip/* + completedColumnBlock * block_step*/;
+                ptrBElement = B/* + (sizeint)(completedColumnBlock * block_step) * b_stride*/;
+            }
+
+            if (!skipToHandlingSubsequentRows)
+            {
+                if (!skiptoCopyingResult)
+                {
+                    if (!partialBlock)
+                    {
+                        Y[0] = ptrBElement[0 * b_stride] - Z[0];
+
+                        dReal p2 = ptrLElement[0];
+                        Y[1] = ptrBElement[1 * b_stride] - Z[1] - p2 * Y[0];
+
+                        ptrLElement += rowSkip;
+
+                        dReal p3 = ptrLElement[0];
+                        dReal p3_1 = ptrLElement[1];
+                        Y[2] = ptrBElement[2 * b_stride] - Z[2] - p3 * Y[0] - p3_1 * Y[1];
+
+                        dReal p4 = ptrLElement[rowSkip];
+                        dReal p4_1 = ptrLElement[1 + rowSkip];
+                        dReal p4_2 = ptrLElement[2 + rowSkip];
+                        Y[3] = ptrBElement[3 * b_stride] - Z[3] - p4 * Y[0] - p4_1 * Y[1] - p4_2 * Y[2];
+                        dSASSERT(block_step == 4);
+                    }
+                    else
+                    {
+                        Y[0] = ptrBElement[0 * b_stride] - Z[0];
+
+                        if (loopX1RowCount >= 2)
+                        {
+                            dReal p2 = ptrLElement[0];
+                            Y[1] = ptrBElement[1 * b_stride] - Z[1] - p2 * Y[0];
+
+                            if (loopX1RowCount > 2)
+                            {
+                                dReal p3 = ptrLElement[0 + rowSkip];
+                                dReal p3_1 = ptrLElement[1 + rowSkip];
+                                Y[2] = ptrBElement[2 * b_stride] - Z[2] - p3 * Y[0] - p3_1 * Y[1];
+                            }
+                        }
+                        dSASSERT(block_step == 4);
+                    }
+
+                    CooperativeAtomics::AtomicReadReorderBarrier();
+
+                    // Use atomic load to make sure memory reads of ptrBElement[] and blockProgressDescriptors[] are not swapped
+                    cellindexint existingDescriptor = blockProgressDescriptors[currentBlock];
+
+                    if (existingDescriptor == INVALID_CELLDESCRIPTOR)
+                    {
+                        // Everything is over -- proceed to subsequent rows
+                        skipToHandlingSubsequentRows = true;
+                    }
+                    else if (existingDescriptor == MAKE_CELLDESCRIPTOR(currentBlock + 1, CCI__MIN, true))
+                    {
+                        // The values computed above may not be valid. Copy the values already in the result context.
+                        skiptoCopyingResult = true;
+                    }
+                    else
+                    {
+                        // The descriptor has not been altered yet - this means the ptrBElement[] values used above were not modified yet 
+                        // and the computation result is valid.
+                        cellindexint newDescriptor = MAKE_CELLDESCRIPTOR(currentBlock + 1, CCI__MIN, true); // put the computation at the top so that the evaluation result from the expression above is reused
+
+                        // Assign the results to the result context (possibly in parallel with other threads 
+                        // that could and ought to be assigning exactly the same values)
+                        SolveL1StraightCellContext &resultContext = buildResultContextRef(cellContexts, currentBlock, blockCount);
+                        resultContext.storePrecalculatedZs(Y);
+
+                        // Assign the result assignment progress descriptor
+                        CooperativeAtomics::AtomicCompareExchangeCellindexint(&blockProgressDescriptors[currentBlock], existingDescriptor, newDescriptor); // the result is to be ignored
+
+                        // Whether succeeded or not, the result is valid, so go on trying to assign it to the matrix
+                    }
+                }
+
+                if (!skipToHandlingSubsequentRows)
+                {
+                    if (skiptoCopyingResult)
+                    {
+                        // Extract the result values stored in the result context
+                        const SolveL1StraightCellContext &resultContext = buildResultContextRef(cellContexts, currentBlock, blockCount);
+                        resultContext.loadPrecalculatedZs(Y);
+
+                        ptrBElement = B + (sizeint)(currentBlock * block_step) * b_stride;
+                    }
+
+                    goAssigningTheResult = true;
+                }
+            }
+        }
+
+        if (goAssigningTheResult)
+        {
+            cellindexint existingDescriptor = blockProgressDescriptors[currentBlock];
+            // Check if the assignment has not been completed yet
+            if (existingDescriptor != INVALID_CELLDESCRIPTOR)
+            {
+                // Assign the computation results to the B vector
+                if (!partialBlock)
+                {
+                    ptrBElement[0 * b_stride] = Y[0];
+                    ptrBElement[1 * b_stride] = Y[1];
+                    ptrBElement[2 * b_stride] = Y[2];
+                    ptrBElement[3 * b_stride] = Y[3];
+                    dSASSERT(block_step == 4);
+                }
+                else
+                {
+                    ptrBElement[0 * b_stride] = Y[0];
+
+                    if (loopX1RowCount >= 2)
+                    {
+                        ptrBElement[1 * b_stride] = Y[1];
+
+                        if (loopX1RowCount > 2)
+                        {
+                            ptrBElement[2 * b_stride] = Y[2];
+                        }
+                    }
+                    dSASSERT(block_step == 4);
+                }
+
+                ThrsafeIncrementIntUpToLimit(&refBlockCompletionProgress, currentBlock + 1);
+                dIASSERT(refBlockCompletionProgress >= currentBlock + 1);
+
+                // And assign the completed status no matter what
+                CooperativeAtomics::AtomicStoreCellindexint(&blockProgressDescriptors[currentBlock], INVALID_CELLDESCRIPTOR);
+            }
+            else 
+            {
+                // everything is over -- just go handling next blocks
+            }
+        }
+
+        if (!stayWithinTheBlock)
+        {
+            completedBlocks = refBlockCompletionProgress;
+
+            if (completedBlocks == blockCount)
+            {
+                break;
+            }
+
+            currentBlock += 1;
+
+            bool lookaheadBoundaryReached = false;
+
+            if (currentBlock == blockCount || completedBlocks == 0)
+            {
+                lookaheadBoundaryReached = true;
+            }
+            else if (currentBlock >= completedBlocks + lookaheadRange)
+            {
+                lookaheadBoundaryReached = blockProcessingState > BPS_NO_BLOCKS_PROCESSED;
+            }
+            else if (currentBlock < completedBlocks)
+            {
+                // Treat detected row advancement as a row processed
+                // blockProcessingState = BPS_SOME_BLOCKS_PROCESSED; <-- performs better without it
+
+                currentBlock = completedBlocks;
+            }
+
+            if (lookaheadBoundaryReached)
+            {
+                dIASSERT(blockProcessingState != BPS_COMPETING_FOR_A_BLOCK); // Why did not we compete???
+
+                // If no row has been processed in the previous pass, compete for the next row to avoid cycling uselessly
+                if (blockProcessingState <= BPS_NO_BLOCKS_PROCESSED)
+                {
+                    // Abandon job if too few blocks remain
+                    if (blockCount - completedBlocks <= ownThreadIndex)
+                    {
+                        break;
+                    }
+
+                    blockProcessingState = BPS_COMPETING_FOR_A_BLOCK;
+                }
+                else
+                {
+                    // If there was some progress, just continue to the next pass
+                    blockProcessingState = BPS_NO_BLOCKS_PROCESSED;
+                }
+
+                currentBlock = completedBlocks;
+            }
+        }
+    }
+}
+
+
+#endif