/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1996-2010 AT&T Intellectual Property *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
/*
* prng
*/
#include <fnv.h>
#define prng_description \
"32 bit PRNG (pseudo random number generator) hash."
#define prng_options "\
[+mpy?The 32 bit PRNG multiplier.]:[number:=0x01000193]\
[+add?The 32 bit PRNG addend.]:[number:=0]\
[+init?The PRNG initial value. 0xffffffff is used if \anumber\a is omitted.]:?[number:=0x811c9dc5]\
"
#define prng_match "prng"
#define prng_done long_done
#define prng_print long_print
#define prng_data long_data
#define prng_scale 0
typedef uint32_t Prngnum_t;
typedef struct Prng_s
{
_SUM_PUBLIC_
_SUM_PRIVATE_
_INTEGRAL_PRIVATE_
Prngnum_t init;
Prngnum_t mpy;
Prngnum_t add;
} Prng_t;
static Sum_t*
prng_open(const Method_t* method, const char* name)
{
register Prng_t* sum;
register const char* s;
register const char* t;
register const char* v;
register int i;
if (sum = newof(0, Prng_t, 1, 0))
{
sum->method = (Method_t*)method;
sum->name = name;
}
s = name;
while (*(t = s))
{
for (t = s, v = 0; *s && *s != '-'; s++)
if (*s == '=' && !v)
v = s;
i = (v ? v : s) - t;
if (isdigit(*t) || v && strneq(t, "mpy", i) && (t = v + 1))
sum->mpy = strtoul(t, NiL, 0);
else if (strneq(t, "add", i))
sum->add = v ? strtoul(v + 1, NiL, 0) : ~sum->add;
else if (strneq(t, "init", i))
sum->init = v ? strtoul(v + 1, NiL, 0) : ~sum->init;
if (*s == '-')
s++;
}
if (!sum->mpy)
{
sum->mpy = FNV_MULT;
if (!sum->init)
sum->init = FNV_INIT;
}
return (Sum_t*)sum;
}
static int
prng_init(Sum_t* p)
{
Prng_t* sum = (Prng_t*)p;
sum->sum = sum->init;
return 0;
}
static int
prng_block(Sum_t* p, const void* s, size_t n)
{
Prng_t* sum = (Prng_t*)p;
register Prngnum_t c = sum->sum;
register unsigned char* b = (unsigned char*)s;
register unsigned char* e = b + n;
while (b < e)
c = c * sum->mpy + sum->add + *b++;
sum->sum = c;
return 0;
}