tomsfastmath/src/mul/fp_mul.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 <tfm.h>

/* c = a * b */
void fp_mul(fp_int *A, fp_int *B, fp_int *C)
{
    int   y, yy;

    /* call generic if we're out of range */
    if (A->used + B->used > FP_SIZE) {
       fp_mul_comba(A, B, C);
       return ;
    }

     y  = MAX(A->used, B->used);
     yy = MIN(A->used, B->used);
    /* pick a comba (unrolled 4/8/16/32 x or rolled) based on the size
       of the largest input.  We also want to avoid doing excess mults if the 
       inputs are not close to the next power of two.  That is, for example,
       if say y=17 then we would do (32-17)^2 = 225 unneeded multiplications 
    */

#ifdef TFM_MUL3 && FP_SIZE >= 6
        if (y <= 3) {
           fp_mul_comba3(A,B,C);
           return;
        }
#endif
#ifdef TFM_MUL4  && FP_SIZE >= 8
        if (y == 4) {
           fp_mul_comba4(A,B,C);
           return;
        }
#endif
#ifdef TFM_MUL6 && FP_SIZE >= 12
        if (y <= 6) {
           fp_mul_comba6(A,B,C);
           return;
        }
#endif
#ifdef TFM_MUL7 && FP_SIZE >= 14
        if (y == 7) {
           fp_mul_comba7(A,B,C);
           return;
        }
#endif
#ifdef TFM_MUL8 && FP_SIZE >= 16
        if (y == 8) {
           fp_mul_comba8(A,B,C);
           return;
        }
#endif
#ifdef TFM_MUL9 && FP_SIZE >= 18
        if (y == 9) {
           fp_mul_comba9(A,B,C);
           return;
        }
#endif
#ifdef TFM_MUL12 && FP_SIZE >= 24
        if (y <= 12) {
           fp_mul_comba12(A,B,C);
           return;
        }
#endif
#ifdef TFM_MUL17 && FP_SIZE >= 34
        if (y <= 17) {
           fp_mul_comba17(A,B,C);
           return;
        }
#endif

#ifdef TFM_SMALL_SET && FP_SIZE >= 32
        if (y <= 16) {
           fp_mul_comba_small(A,B,C);
           return;
        }
#endif        
#if defined(TFM_MUL20) && FP_SIZE >= 40
        if (y <= 20) {
           fp_mul_comba20(A,B,C);
           return;
        }
#endif
#if defined(TFM_MUL24) && FP_SIZE >= 48
        if (yy >= 16 && y <= 24) {
           fp_mul_comba24(A,B,C);
           return;
        }
#endif
#if defined(TFM_MUL28) && FP_SIZE >= 56
        if (yy >= 20 && y <= 28) {
           fp_mul_comba28(A,B,C);
           return;
        }
#endif
#if defined(TFM_MUL32) && FP_SIZE >= 64
        if (yy >= 24 && y <= 32) {
           fp_mul_comba32(A,B,C);
           return;
        }
#endif
#if defined(TFM_MUL48) && FP_SIZE >= 96
        if (yy >= 40 && y <= 48) {
           fp_mul_comba48(A,B,C);
           return;
        }
#endif        
#if defined(TFM_MUL64) && FP_SIZE >= 128
        if (yy >= 56 && y <= 64) {
           fp_mul_comba64(A,B,C);
           return;
        }
#endif
        fp_mul_comba(A,B,C);
}


/* $Source: /cvs/libtom/tomsfastmath/src/mul/fp_mul.c,v $ */
/* $Revision: 1.1 $ */
/* $Date: 2006/12/31 21:25:53 $ */