/***********************************************************************
* *
* 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
/*
* att
*/
#define att_description \
"The system 5 release 4 checksum. This is the default for \bsum\b \
when \bgetconf UNIVERSE\b is \batt\b. This is the only true sum; \
all of the other methods are order dependent."
#define att_options 0
#define att_match "att|sys5|s5|default"
#define att_open long_open
#define att_init long_init
#define att_print long_print
#define att_data long_data
#define att_scale 512
#if defined(__SUNPRO_C) || defined(__GNUC__)
#if defined(__SUNPRO_C)
# include <sun_prefetch.h>
# define sum_prefetch(addr) sun_prefetch_read_many((void *)(addr))
#elif defined(__GNUC__)
# define sum_prefetch(addr) __builtin_prefetch((addr), 0, 3)
#else
# error Unknown compiler
#endif
#define CBLOCK_SIZE (64)
#pragma unroll(16)
/* Inmos transputer would love this algorithm */
static int
att_block(register Sum_t* p, const void* s, size_t n)
{
register uint32_t c = ((Integral_t*)p)->sum;
register const unsigned char* b = (const unsigned char*)s;
register const unsigned char* e = b + n;
register uint32_t s0, s1, s2, s3, s4, s5, s6, s7;
register unsigned int i;
s0=s1=s2=s3=s4=s5=s6=s7=0U;
sum_prefetch((void *)b);
while (n > CBLOCK_SIZE)
{
sum_prefetch((b+CBLOCK_SIZE));
/* Compiler will unroll for() loops per #pragma unroll */
for (i=0 ; i < (CBLOCK_SIZE/8) ; i++)
{
/*
* use s0-s7 to decouple calculations (this improves pipelining)
* because each operation is completely independent from it's
* siblings
*/
s0+=b[0];
s1+=b[1];
s2+=b[2];
s3+=b[3];
s4+=b[4];
s5+=b[5];
s6+=b[6];
s7+=b[7];
b+=8;
n-=8;
}
}
c+=s0+s1+s2+s3+s4+s5+s6+s7;
while (b < e)
c += *b++;
((Integral_t*)p)->sum = c;
return 0;
}
#else
static int
att_block(register Sum_t* p, const void* s, size_t n)
{
register uint32_t c = ((Integral_t*)p)->sum;
register unsigned char* b = (unsigned char*)s;
register unsigned char* e = b + n;
while (b < e)
c += *b++;
((Integral_t*)p)->sum = c;
return 0;
}
#endif /* defined(__SUNPRO_C) || defined(__GNUC__) */
static int
att_done(Sum_t* p)
{
register uint32_t c = ((Integral_t*)p)->sum;
c = (c & 0xffff) + ((c >> 16) & 0xffff);
c = (c & 0xffff) + (c >> 16);
((Integral_t*)p)->sum = c & 0xffff;
return short_done(p);
}