test: Added a better PRNG (pseudorandom number generator)

This adds a fast SIMD-optimized variant of a small noncryptographic
PRNG originally developed by Bob Jenkins:
    http://www.burtleburtle.net/bob/rand/smallprng.html

The generated pseudorandom data is good enough to pass "Big Crush"
tests from TestU01 (http://en.wikipedia.org/wiki/TestU01).

SIMD code uses http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html
which is a GCC specific extension. There is also a slower alternative
code path, which should work with any C compiler.

The performance of filling buffer with random data:
   Intel Core i7  @2.8GHz (SSE2)     : ~5.9 GB/s
   ARM Cortex-A15 @1.7GHz (NEON)     : ~2.2 GB/s
   IBM Cell PPU   @3.2GHz (Altivec)  : ~1.7 GB/s

4 files changed, 581 insertions, 0 deletions

diff --git a/test/Makefile.sources b/test/Makefile.sources
index 07789716..8c0b505d 100644
--- a/test/Makefile.sources
+++ b/test/Makefile.sources
@@ -1,5 +1,6 @@
 # Tests (sorted by expected completion time)
 TESTPROGRAMS =			\
+	prng-test		\
 	a1-trap-test		\
 	pdf-op-test		\
 	region-test		\
@@ -33,8 +34,10 @@ BENCHMARKS =			\
 # Utility functions
 libutils_sources =		\
 	utils.c			\
+	utils-prng.c		\
 	$(NULL)
 
 libutils_headers =		\
 	utils.h			\
+	utils-prng.h		\
 	$(NULL)
diff --git a/test/prng-test.c b/test/prng-test.c
new file mode 100644
index 00000000..0a3ad5e8
--- /dev/null
+++ b/test/prng-test.c
@@ -0,0 +1,172 @@
+/*
+ * 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 <assert.h>
+#include <stdlib.h>
+#include "utils-prng.h"
+#include "utils.h"
+
+/* The original code from http://www.burtleburtle.net/bob/rand/smallprng.html */
+
+typedef uint32_t u4;
+typedef struct ranctx { u4 a; u4 b; u4 c; u4 d; } ranctx;
+
+#define rot(x,k) (((x)<<(k))|((x)>>(32-(k))))
+u4 ranval( ranctx *x ) {
+    u4 e = x->a - rot(x->b, 27);
+    x->a = x->b ^ rot(x->c, 17);
+    x->b = x->c + x->d;
+    x->c = x->d + e;
+    x->d = e + x->a;
+    return x->d;
+}
+
+void raninit( ranctx *x, u4 seed ) {
+    u4 i;
+    x->a = 0xf1ea5eed, x->b = x->c = x->d = seed;
+    for (i=0; i<20; ++i) {
+        (void)ranval(x);
+    }
+}
+
+/*****************************************************************************/
+
+#define BUFSIZE (8 * 1024 * 1024)
+#define N 50
+
+void bench (void)
+{
+    double t1, t2;
+    int i;
+    prng_t prng;
+    uint8_t *buf = aligned_malloc (16, BUFSIZE + 1);
+
+    prng_srand_r (&prng, 1234);
+    t1 = gettime();
+    for (i = 0; i < N; i++)
+        prng_randmemset_r (&prng, buf, BUFSIZE, 0);
+    t2 = gettime();
+    printf ("aligned randmemset                    : %.2f MB/s\n",
+            (double)BUFSIZE * N / 1000000. / (t2 - t1));
+
+    t1 = gettime();
+    for (i = 0; i < N; i++)
+        prng_randmemset_r (&prng, buf + 1, BUFSIZE, 0);
+    t2 = gettime();
+    printf ("unaligned randmemset                  : %.2f MB/s\n",
+            (double)BUFSIZE * N / 1000000. / (t2 - t1));
+
+    t1 = gettime();
+    for (i = 0; i < N; i++)
+    {
+        prng_randmemset_r (&prng, buf, BUFSIZE, RANDMEMSET_MORE_00_AND_FF);
+    }
+    t2 = gettime ();
+    printf ("aligned randmemset (more 00 and FF)   : %.2f MB/s\n",
+            (double)BUFSIZE * N / 1000000. / (t2 - t1));
+
+    t1 = gettime();
+    for (i = 0; i < N; i++)
+    {
+        prng_randmemset_r (&prng, buf + 1, BUFSIZE, RANDMEMSET_MORE_00_AND_FF);
+    }
+    t2 = gettime ();
+    printf ("unaligned randmemset (more 00 and FF) : %.2f MB/s\n",
+            (double)BUFSIZE * N / 1000000. / (t2 - t1));
+
+    free (buf);
+}
+
+#define SMALLBUFSIZE 100
+
+int main (int argc, char *argv[])
+{
+    const uint32_t ref_crc[RANDMEMSET_MORE_00_AND_FF + 1] =
+    {
+        0xBA06763D, 0x103FC550, 0x8B59ABA5, 0xD82A0F39
+    };
+    uint32_t crc1, crc2;
+    uint32_t ref, seed, seed0, seed1, seed2, seed3;
+    prng_rand_128_data_t buf;
+    uint8_t *bytebuf = aligned_malloc(16, SMALLBUFSIZE + 1);
+    ranctx x;
+    prng_t prng;
+    prng_randmemset_flags_t flags;
+
+    if (argc > 1 && strcmp(argv[1], "-bench") == 0)
+    {
+        bench ();
+        return 0;
+    }
+
+    /* basic test */
+    raninit (&x, 0);
+    prng_srand_r (&prng, 0);
+    assert (ranval (&x) == prng_rand_r (&prng));
+
+    /* test for simd code */
+    seed = 0;
+    prng_srand_r (&prng, seed);
+    seed0 = (seed = seed * 1103515245 + 12345);
+    seed1 = (seed = seed * 1103515245 + 12345);
+    seed2 = (seed = seed * 1103515245 + 12345);
+    seed3 = (seed = seed * 1103515245 + 12345);
+    prng_rand_128_r (&prng, &buf);
+
+    raninit (&x, seed0);
+    ref = ranval (&x);
+    assert (ref == buf.w[0]);
+
+    raninit (&x, seed1);
+    ref = ranval (&x);
+    assert (ref == buf.w[1]);
+
+    raninit (&x, seed2);
+    ref = ranval (&x);
+    assert (ref == buf.w[2]);
+
+    raninit (&x, seed3);
+    ref = ranval (&x);
+    assert (ref == buf.w[3]);
+
+    /* test for randmemset */
+    for (flags = 0; flags <= RANDMEMSET_MORE_00_AND_FF; flags++)
+    {
+        prng_srand_r (&prng, 1234);
+        prng_randmemset_r (&prng, bytebuf, 16, flags);
+        prng_randmemset_r (&prng, bytebuf + 16, SMALLBUFSIZE - 17, flags);
+        crc1 = compute_crc32 (0, bytebuf, SMALLBUFSIZE - 1);
+        prng_srand_r (&prng, 1234);
+        prng_randmemset_r (&prng, bytebuf + 1, SMALLBUFSIZE - 1, flags);
+        crc2 = compute_crc32 (0, bytebuf + 1, SMALLBUFSIZE - 1);
+        assert (ref_crc[flags] == crc1);
+        assert (ref_crc[flags] == crc2);
+    }
+
+    free (bytebuf);
+
+    return 0;
+}
diff --git a/test/utils-prng.c b/test/utils-prng.c
new file mode 100644
index 00000000..7c2dd6a9
--- /dev/null
+++ b/test/utils-prng.c
@@ -0,0 +1,238 @@
+/*
+ * 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"
+
+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 GCC_VECTOR_EXTENSIONS_SUPPORTED
+    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 GCC_VECTOR_EXTENSIONS_SUPPORTED
+    if (aligned)
+    {
+        *(uint8x16 *)addr = d->vb;
+        return;
+    }
+#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;
+
+    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 GCC_VECTOR_EXTENSIONS_SUPPORTED
+            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);
+            }
+#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;                                 \
+                }
+
+            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
+        {
+#ifdef GCC_VECTOR_EXTENSIONS_SUPPORTED
+            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);
+            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;
+    }
+    while (size > 0)
+    {
+        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;
+        }
+        *buf++ = randbyte;
+        size--;
+    }
+    *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
+ */
+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);
+    }
+}
diff --git a/test/utils-prng.h b/test/utils-prng.h
new file mode 100644
index 00000000..285107f0
--- /dev/null
+++ b/test/utils-prng.h
@@ -0,0 +1,168 @@
+/*
+ * 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.
+ */
+
+#ifndef __UTILS_PRNG_H__
+#define __UTILS_PRNG_H__
+
+/*
+ * This file provides a fast SIMD-optimized noncryptographic PRNG (pseudorandom
+ * number generator), with the output good enough to pass "Big Crush" tests
+ * from TestU01 (http://en.wikipedia.org/wiki/TestU01).
+ *
+ * SIMD code uses http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html
+ * which is a GCC specific extension. There is also a slower alternative
+ * code path, which should work with any C compiler.
+ *
+ * The "prng_t" structure keeps the internal state of the random number
+ * generator. It is possible to have multiple instances of the random number
+ * generator active at the same time, in this case each of them needs to have
+ * its own "prng_t". All the functions take a pointer to "prng_t"
+ * as the first argument.
+ *
+ * Functions:
+ *
+ * ----------------------------------------------------------------------------
+ * void prng_srand_r (prng_t *prng, uint32_t seed);
+ *
+ * Initialize the pseudorandom number generator. The sequence of preudorandom
+ * numbers is deterministic and only depends on "seed". Any two generators
+ * initialized with the same seed will produce exactly the same sequence.
+ *
+ * ----------------------------------------------------------------------------
+ * uint32_t prng_rand_r (prng_t *prng);
+ *
+ * Generate a single uniformly distributed 32-bit pseudorandom value.
+ *
+ * ----------------------------------------------------------------------------
+ * void prng_randmemset_r (prng_t                  *prng,
+ *                         void                    *buffer,
+ *                         size_t                   size,
+ *                         prng_randmemset_flags_t  flags);
+ *
+ * Fills the memory buffer "buffer" with "size" bytes of pseudorandom data.
+ * The "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
+ * The flags can be combined. This allows a bit better simulation of typical
+ * pixel data, which normally contains a lot of fully transparent or fully
+ * opaque pixels.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "pixman-private.h"
+
+/*****************************************************************************/
+
+#if defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7))
+#define GCC_VECTOR_EXTENSIONS_SUPPORTED
+typedef uint32_t uint32x4 __attribute__ ((vector_size(16)));
+typedef uint8_t  uint8x16 __attribute__ ((vector_size(16)));
+#endif
+
+typedef struct
+{
+    uint32_t a, b, c, d;
+} smallprng_t;
+
+typedef struct
+{
+#ifdef GCC_VECTOR_EXTENSIONS_SUPPORTED
+    uint32x4 a, b, c, d;
+#else
+    smallprng_t p1, p2, p3, p4;
+#endif
+    smallprng_t p0;
+} prng_t;
+
+typedef union
+{
+    uint8_t  b[16];
+    uint32_t w[4];
+#ifdef GCC_VECTOR_EXTENSIONS_SUPPORTED
+    uint8x16 vb;
+    uint32x4 vw;
+#endif
+} prng_rand_128_data_t;
+
+/*****************************************************************************/
+
+static force_inline uint32_t
+smallprng_rand_r (smallprng_t *x)
+{
+    uint32_t e = x->a - ((x->b << 27) + (x->b >> (32 - 27)));
+    x->a = x->b ^ ((x->c << 17) ^ (x->c >> (32 - 17)));
+    x->b = x->c + x->d;
+    x->c = x->d + e;
+    x->d = e + x->a;
+    return x->d;
+}
+
+/* Generate 4 bytes (32-bits) of random data */
+static force_inline uint32_t
+prng_rand_r (prng_t *x)
+{
+    return smallprng_rand_r (&x->p0);
+}
+
+/* Generate 16 bytes (128-bits) of random data */
+static force_inline void
+prng_rand_128_r (prng_t *x, prng_rand_128_data_t *data)
+{
+#ifdef GCC_VECTOR_EXTENSIONS_SUPPORTED
+    uint32x4 e = x->a - ((x->b << 27) + (x->b >> (32 - 27)));
+    x->a = x->b ^ ((x->c << 17) ^ (x->c >> (32 - 17)));
+    x->b = x->c + x->d;
+    x->c = x->d + e;
+    x->d = e + x->a;
+    data->vw = x->d;
+#else
+    data->w[0] = smallprng_rand_r (&x->p1);
+    data->w[1] = smallprng_rand_r (&x->p2);
+    data->w[2] = smallprng_rand_r (&x->p3);
+    data->w[3] = smallprng_rand_r (&x->p4);
+#endif
+}
+
+typedef enum
+{
+    RANDMEMSET_MORE_00        = 1, /* ~25% chance for 0x00 bytes */
+    RANDMEMSET_MORE_FF        = 2, /* ~25% chance for 0xFF bytes */
+    RANDMEMSET_MORE_00_AND_FF = (RANDMEMSET_MORE_00 | RANDMEMSET_MORE_FF)
+} prng_randmemset_flags_t;
+
+/* Set the 32-bit seed for PRNG */
+void prng_srand_r (prng_t *prng, uint32_t seed);
+
+/* Fill memory buffer with random data */
+void prng_randmemset_r (prng_t                  *prng,
+                        void                    *buffer,
+                        size_t                   size,
+                        prng_randmemset_flags_t  flags);
+
+#endif