67 lines
1.7 KiB
C
67 lines
1.7 KiB
C
|
/* TomsFastMath, a fast ISO C bignum library.
|
||
|
|
*
|
||
|
|
* This project is meant to fill in where LibTomMath
|
||
|
|
* falls short. That is speed ;-)
|
||
|
|
*
|
||
|
|
* This project is public domain and free for all purposes.
|
||
|
|
*
|
||
|
|
* Tom St Denis, tomstdenis@gmail.com
|
||
|
|
*/
|
||
|
|
#include "bignum_fast.h"
|
||
|
|
|
||
|
|
void fp_read_unsigned_bin(fp_int *a, const unsigned char *b, int c)
|
||
|
|
{
|
||
|
|
/* zero the int */
|
||
|
|
fp_zero (a);
|
||
|
|
|
||
|
|
/* If we know the endianness of this architecture, and we're using
|
||
|
|
32-bit fp_digits, we can optimize this */
|
||
|
|
#if (defined(ENDIAN_LITTLE) || defined(ENDIAN_BIG)) && !defined(FP_64BIT)
|
||
|
|
/* But not for both simultaneously */
|
||
|
|
#if defined(ENDIAN_LITTLE) && defined(ENDIAN_BIG)
|
||
|
|
#error Both ENDIAN_LITTLE and ENDIAN_BIG defined.
|
||
|
|
#endif
|
||
|
|
{
|
||
|
|
unsigned char *pd = (unsigned char *)a->dp;
|
||
|
|
|
||
|
|
if ((unsigned)c > (FP_SIZE * sizeof(fp_digit))) {
|
||
|
|
int excess = c - (FP_SIZE * sizeof(fp_digit));
|
||
|
|
c -= excess;
|
||
|
|
b += excess;
|
||
|
|
}
|
||
|
|
a->used = (c + sizeof(fp_digit) - 1)/sizeof(fp_digit);
|
||
|
|
/* read the bytes in */
|
||
|
|
#ifdef ENDIAN_BIG
|
||
|
|
{
|
||
|
|
/* Use Duff's device to unroll the loop. */
|
||
|
|
int idx = (c - 1) & ~3;
|
||
|
|
switch (c % 4) {
|
||
|
|
case 0: do { pd[idx+0] = *b++;
|
||
|
|
case 3: pd[idx+1] = *b++;
|
||
|
|
case 2: pd[idx+2] = *b++;
|
||
|
|
case 1: pd[idx+3] = *b++;
|
||
|
|
idx -= 4;
|
||
|
|
} while ((c -= 4) > 0);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
#else
|
||
|
|
for (c -= 1; c >= 0; c -= 1) {
|
||
|
|
pd[c] = *b++;
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
}
|
||
|
|
#else
|
||
|
|
/* read the bytes in */
|
||
|
|
for (; c > 0; c--) {
|
||
|
|
fp_mul_2d (a, 8, a);
|
||
|
|
a->dp[0] |= *b++;
|
||
|
|
a->used += 1;
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
fp_clamp (a);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* $Source: /cvs/libtom/tomsfastmath/src/bin/fp_read_unsigned_bin.c,v $ */
|
||
|
|
/* $Revision: 1.2 $ */
|
||
|
|
/* $Date: 2007/02/17 02:58:19 $ */
|