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/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1996-2008 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
/*
* crc
*/
#define crc_description \
"32 bit CRC (cyclic redundancy check)."
#define crc_options "\
[+polynomial?The 32 bit crc polynomial bitmask with implicit bit 32.]:[mask:=0xedb88320]\
[+done?XOR the final crc value with \anumber\a. 0xffffffff is used if \anumber\a is omitted.]:?[number:=0]\
[+init?The initial crc value. 0xffffffff is used if \anumber\a is omitted.]:?[number:=0]\
[+rotate?XOR each input character with the high order crc byte (instead of the low order).]\
[+size?Include the total number of bytes in the crc. \anumber\a, if specified, is first XOR'd into the size.]:?[number:=0]\
"
#define crc_match "crc"
#define crc_open crc_open
#define crc_print long_print
#define crc_data long_data
#define crc_scale 0
typedef uint32_t Crcnum_t;
typedef struct Crc_s
{
_SUM_PUBLIC_
_SUM_PRIVATE_
_INTEGRAL_PRIVATE_
Crcnum_t init;
Crcnum_t done;
Crcnum_t xorsize;
Crcnum_t tab[256];
unsigned int addsize;
unsigned int rotate;
} Crc_t;
#define CRC(p,s,c) (s = (s >> 8) ^ (p)->tab[(s ^ (c)) & 0xff])
#define CRCROTATE(p,s,c) (s = (s << 8) ^ (p)->tab[((s >> 24) ^ (c)) & 0xff])
static Sum_t*
crc_open(const Method_t* method, const char* name)
{
register Crc_t* sum;
register const char* s;
register const char* t;
register const char* v;
register int i;
register int j;
Crcnum_t polynomial;
Crcnum_t x;
if (sum = newof(0, Crc_t, 1, 0))
{
sum->method = (Method_t*)method;
sum->name = name;
}
polynomial = 0xedb88320;
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 && i >= 4 && strneq(t, "poly", 4) && (t = v + 1))
polynomial = strtoul(t, NiL, 0);
else if (strneq(t, "done", i))
sum->done = v ? strtoul(v + 1, NiL, 0) : ~sum->done;
else if (strneq(t, "init", i))
sum->init = v ? strtoul(v + 1, NiL, 0) : ~sum->init;
else if (strneq(t, "rotate", i))
sum->rotate = 1;
else if (strneq(t, "size", i))
{
sum->addsize = 1;
if (v)
sum->xorsize = strtoul(v + 1, NiL, 0);
}
if (*s == '-')
s++;
}
if (sum->rotate)
{
Crcnum_t t;
Crcnum_t p[8];
p[0] = polynomial;
for (i = 1; i < 8; i++)
p[i] = (p[i-1] << 1) ^ ((p[i-1] & 0x80000000) ? polynomial : 0);
for (i = 0; i < elementsof(sum->tab); i++)
{
t = 0;
x = i;
for (j = 0; j < 8; j++)
{
if (x & 1)
t ^= p[j];
x >>= 1;
}
sum->tab[i] = t;
}
}
else
{
for (i = 0; i < elementsof(sum->tab); i++)
{
x = i;
for (j = 0; j < 8; j++)
x = (x>>1) ^ ((x & 1) ? polynomial : 0);
sum->tab[i] = x;
}
}
return (Sum_t*)sum;
}
static int
crc_init(Sum_t* p)
{
Crc_t* sum = (Crc_t*)p;
sum->sum = sum->init;
return 0;
}
static int
crc_block(Sum_t* p, const void* s, size_t n)
{
Crc_t* sum = (Crc_t*)p;
register Crcnum_t c = sum->sum;
register unsigned char* b = (unsigned char*)s;
register unsigned char* e = b + n;
if (sum->rotate)
while (b < e)
CRCROTATE(sum, c, *b++);
else
while (b < e)
CRC(sum, c, *b++);
sum->sum = c;
return 0;
}
static int
crc_done(Sum_t* p)
{
register Crc_t* sum = (Crc_t*)p;
register Crcnum_t c;
register uintmax_t n;
int i;
int j;
c = sum->sum;
if (sum->addsize)
{
n = sum->size ^ sum->xorsize;
if (sum->rotate)
while (n)
{
CRCROTATE(sum, c, n);
n >>= 8;
}
else
for (i = 0, j = 32; i < 4; i++)
{
j -= 8;
CRC(sum, c, n >> j);
}
}
sum->sum = c ^ sum->done;
sum->total_sum ^= (sum->sum &= 0xffffffff);
return 0;
}
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