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+/*
+ * Copyright © 2012 Siarhei Siamashka <siarhei.siamashka@gmail.com>
+ *
+ * Based on the public domain implementation of small noncryptographic PRNG
+ * authored by Bob Jenkins: http://burtleburtle.net/bob/rand/smallprng.html
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include "utils.h"
+#include "utils-prng.h"
+
+#if defined(HAVE_GCC_VECTOR_EXTENSIONS) && defined(__SSE2__)
+#include <xmmintrin.h>
+#endif
+
+void smallprng_srand_r (smallprng_t *x, uint32_t seed)
+{
+ uint32_t i;
+ x->a = 0xf1ea5eed, x->b = x->c = x->d = seed;
+ for (i = 0; i < 20; ++i)
+ smallprng_rand_r (x);
+}
+
+/*
+ * Set a 32-bit seed for PRNG
+ *
+ * LCG is used here for generating independent seeds for different
+ * smallprng instances (in the case if smallprng is also used for
+ * generating these seeds, "Big Crush" test from TestU01 detects
+ * some problems in the glued 'prng_rand_128_r' output data).
+ * Actually we might be even better using some cryptographic
+ * hash for this purpose, but LCG seems to be also enough for
+ * passing "Big Crush".
+ */
+void prng_srand_r (prng_t *x, uint32_t seed)
+{
+#ifdef HAVE_GCC_VECTOR_EXTENSIONS
+ int i;
+ prng_rand_128_data_t dummy;
+ smallprng_srand_r (&x->p0, seed);
+ x->a[0] = x->a[1] = x->a[2] = x->a[3] = 0xf1ea5eed;
+ x->b[0] = x->c[0] = x->d[0] = (seed = seed * 1103515245 + 12345);
+ x->b[1] = x->c[1] = x->d[1] = (seed = seed * 1103515245 + 12345);
+ x->b[2] = x->c[2] = x->d[2] = (seed = seed * 1103515245 + 12345);
+ x->b[3] = x->c[3] = x->d[3] = (seed = seed * 1103515245 + 12345);
+ for (i = 0; i < 20; ++i)
+ prng_rand_128_r (x, &dummy);
+#else
+ smallprng_srand_r (&x->p0, seed);
+ smallprng_srand_r (&x->p1, (seed = seed * 1103515245 + 12345));
+ smallprng_srand_r (&x->p2, (seed = seed * 1103515245 + 12345));
+ smallprng_srand_r (&x->p3, (seed = seed * 1103515245 + 12345));
+ smallprng_srand_r (&x->p4, (seed = seed * 1103515245 + 12345));
+#endif
+}
+
+static force_inline void
+store_rand_128_data (void *addr, prng_rand_128_data_t *d, int aligned)
+{
+#ifdef HAVE_GCC_VECTOR_EXTENSIONS
+ if (aligned)
+ {
+ *(uint8x16 *)addr = d->vb;
+ return;
+ }
+ else
+ {
+#ifdef __SSE2__
+ /* workaround for http://gcc.gnu.org/PR55614 */
+ _mm_storeu_si128 (addr, _mm_loadu_si128 ((__m128i *)d));
+ return;
+#endif
+ }
+#endif
+ /* we could try something better for unaligned writes (packed attribute),
+ * but GCC is not very reliable: http://gcc.gnu.org/PR55454 */
+ memcpy (addr, d, 16);
+}
+
+/*
+ * Helper function and the actual code for "prng_randmemset_r" function
+ */
+static force_inline void
+randmemset_internal (prng_t *prng,
+ uint8_t *buf,
+ size_t size,
+ prng_randmemset_flags_t flags,
+ int aligned)
+{
+ prng_t local_prng = *prng;
+ prng_rand_128_data_t randdata;
+ size_t i;
+
+ while (size >= 16)
+ {
+ prng_rand_128_data_t t;
+ if (flags == 0)
+ {
+ prng_rand_128_r (&local_prng, &randdata);
+ }
+ else
+ {
+ prng_rand_128_r (&local_prng, &t);
+ prng_rand_128_r (&local_prng, &randdata);
+#ifdef HAVE_GCC_VECTOR_EXTENSIONS
+ if (flags & RANDMEMSET_MORE_FF)
+ {
+ const uint8x16 const_C0 =
+ {
+ 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0,
+ 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0
+ };
+ randdata.vb |= (t.vb >= const_C0);
+ }
+ if (flags & RANDMEMSET_MORE_00)
+ {
+ const uint8x16 const_40 =
+ {
+ 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+ 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40
+ };
+ randdata.vb &= (t.vb >= const_40);
+ }
+ if (flags & RANDMEMSET_MORE_FFFFFFFF)
+ {
+ const uint32x4 const_C0000000 =
+ {
+ 0xC0000000, 0xC0000000, 0xC0000000, 0xC0000000
+ };
+ randdata.vw |= ((t.vw << 30) >= const_C0000000);
+ }
+ if (flags & RANDMEMSET_MORE_00000000)
+ {
+ const uint32x4 const_40000000 =
+ {
+ 0x40000000, 0x40000000, 0x40000000, 0x40000000
+ };
+ randdata.vw &= ((t.vw << 30) >= const_40000000);
+ }
+#else
+ #define PROCESS_ONE_LANE(i) \
+ if (flags & RANDMEMSET_MORE_FF) \
+ { \
+ uint32_t mask_ff = (t.w[i] & (t.w[i] << 1)) & 0x80808080; \
+ mask_ff |= mask_ff >> 1; \
+ mask_ff |= mask_ff >> 2; \
+ mask_ff |= mask_ff >> 4; \
+ randdata.w[i] |= mask_ff; \
+ } \
+ if (flags & RANDMEMSET_MORE_00) \
+ { \
+ uint32_t mask_00 = (t.w[i] | (t.w[i] << 1)) & 0x80808080; \
+ mask_00 |= mask_00 >> 1; \
+ mask_00 |= mask_00 >> 2; \
+ mask_00 |= mask_00 >> 4; \
+ randdata.w[i] &= mask_00; \
+ } \
+ if (flags & RANDMEMSET_MORE_FFFFFFFF) \
+ { \
+ int32_t mask_ff = ((t.w[i] << 30) & (t.w[i] << 31)) & \
+ 0x80000000; \
+ randdata.w[i] |= mask_ff >> 31; \
+ } \
+ if (flags & RANDMEMSET_MORE_00000000) \
+ { \
+ int32_t mask_00 = ((t.w[i] << 30) | (t.w[i] << 31)) & \
+ 0x80000000; \
+ randdata.w[i] &= mask_00 >> 31; \
+ }
+
+ PROCESS_ONE_LANE (0)
+ PROCESS_ONE_LANE (1)
+ PROCESS_ONE_LANE (2)
+ PROCESS_ONE_LANE (3)
+#endif
+ }
+ if (is_little_endian ())
+ {
+ store_rand_128_data (buf, &randdata, aligned);
+ buf += 16;
+ }
+ else
+ {
+
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+#ifdef HAVE_GCC_VECTOR_EXTENSIONS
+# if __has_builtin(__builtin_shufflevector)
+ randdata.vb =
+ __builtin_shufflevector (randdata.vb, randdata.vb,
+ 3, 2, 1, 0, 7, 6 , 5, 4,
+ 11, 10, 9, 8, 15, 14, 13, 12);
+# else
+ static const uint8x16 bswap_shufflemask =
+ {
+ 3, 2, 1, 0, 7, 6, 5, 4, 11, 10, 9, 8, 15, 14, 13, 12
+ };
+ randdata.vb = __builtin_shuffle (randdata.vb, bswap_shufflemask);
+# endif
+
+ store_rand_128_data (buf, &randdata, aligned);
+ buf += 16;
+#else
+ uint8_t t1, t2, t3, t4;
+ #define STORE_ONE_LANE(i) \
+ t1 = randdata.b[i * 4 + 3]; \
+ t2 = randdata.b[i * 4 + 2]; \
+ t3 = randdata.b[i * 4 + 1]; \
+ t4 = randdata.b[i * 4 + 0]; \
+ *buf++ = t1; \
+ *buf++ = t2; \
+ *buf++ = t3; \
+ *buf++ = t4;
+
+ STORE_ONE_LANE (0)
+ STORE_ONE_LANE (1)
+ STORE_ONE_LANE (2)
+ STORE_ONE_LANE (3)
+#endif
+ }
+ size -= 16;
+ }
+ i = 0;
+ while (i < size)
+ {
+ uint8_t randbyte = prng_rand_r (&local_prng) & 0xFF;
+ if (flags != 0)
+ {
+ uint8_t t = prng_rand_r (&local_prng) & 0xFF;
+ if ((flags & RANDMEMSET_MORE_FF) && (t >= 0xC0))
+ randbyte = 0xFF;
+ if ((flags & RANDMEMSET_MORE_00) && (t < 0x40))
+ randbyte = 0x00;
+ if (i % 4 == 0 && i + 4 <= size)
+ {
+ t = prng_rand_r (&local_prng) & 0xFF;
+ if ((flags & RANDMEMSET_MORE_FFFFFFFF) && (t >= 0xC0))
+ {
+ memset(&buf[i], 0xFF, 4);
+ i += 4;
+ continue;
+ }
+ if ((flags & RANDMEMSET_MORE_00000000) && (t < 0x40))
+ {
+ memset(&buf[i], 0x00, 4);
+ i += 4;
+ continue;
+ }
+ }
+ }
+ buf[i] = randbyte;
+ i++;
+ }
+ *prng = local_prng;
+}
+
+/*
+ * Fill memory buffer with random data. Flags argument may be used
+ * to tweak some statistics properties:
+ * RANDMEMSET_MORE_00 - set ~25% of bytes to 0x00
+ * RANDMEMSET_MORE_FF - set ~25% of bytes to 0xFF
+ * RANDMEMSET_MORE_00000000 - ~25% chance for 00000000 4-byte clusters
+ * RANDMEMSET_MORE_FFFFFFFF - ~25% chance for FFFFFFFF 4-byte clusters
+ */
+void prng_randmemset_r (prng_t *prng,
+ void *voidbuf,
+ size_t size,
+ prng_randmemset_flags_t flags)
+{
+ uint8_t *buf = (uint8_t *)voidbuf;
+ if ((uintptr_t)buf & 15)
+ {
+ /* unaligned buffer */
+ if (flags == 0)
+ randmemset_internal (prng, buf, size, 0, 0);
+ else if (flags == RANDMEMSET_MORE_00_AND_FF)
+ randmemset_internal (prng, buf, size, RANDMEMSET_MORE_00_AND_FF, 0);
+ else
+ randmemset_internal (prng, buf, size, flags, 0);
+ }
+ else
+ {
+ /* aligned buffer */
+ if (flags == 0)
+ randmemset_internal (prng, buf, size, 0, 1);
+ else if (flags == RANDMEMSET_MORE_00_AND_FF)
+ randmemset_internal (prng, buf, size, RANDMEMSET_MORE_00_AND_FF, 1);
+ else
+ randmemset_internal (prng, buf, size, flags, 1);
+ }
+}
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