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view tomsfastmath/src/mul/fp_mul.c @ 643:a362b62d38b2 dropbear-tfm
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author | Matt Johnston <matt@ucc.asn.au> |
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date | Wed, 23 Nov 2011 18:10:20 +0700 |
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/* 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, [email protected] */ #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 if (y <= 3) { fp_mul_comba3(A,B,C); return; } #endif #ifdef TFM_MUL4 if (y == 4) { fp_mul_comba4(A,B,C); return; } #endif #ifdef TFM_MUL6 if (y <= 6) { fp_mul_comba6(A,B,C); return; } #endif #ifdef TFM_MUL7 if (y == 7) { fp_mul_comba7(A,B,C); return; } #endif #ifdef TFM_MUL8 if (y == 8) { fp_mul_comba8(A,B,C); return; } #endif #ifdef TFM_MUL9 if (y == 9) { fp_mul_comba9(A,B,C); return; } #endif #ifdef TFM_MUL12 if (y <= 12) { fp_mul_comba12(A,B,C); return; } #endif #ifdef TFM_MUL17 if (y <= 17) { fp_mul_comba17(A,B,C); return; } #endif #ifdef TFM_SMALL_SET if (y <= 16) { fp_mul_comba_small(A,B,C); return; } #endif #if defined(TFM_MUL20) if (y <= 20) { fp_mul_comba20(A,B,C); return; } #endif #if defined(TFM_MUL24) if (yy >= 16 && y <= 24) { fp_mul_comba24(A,B,C); return; } #endif #if defined(TFM_MUL28) if (yy >= 20 && y <= 28) { fp_mul_comba28(A,B,C); return; } #endif #if defined(TFM_MUL32) if (yy >= 24 && y <= 32) { fp_mul_comba32(A,B,C); return; } #endif #if defined(TFM_MUL48) if (yy >= 40 && y <= 48) { fp_mul_comba48(A,B,C); return; } #endif #if defined(TFM_MUL64) if (yy >= 56 && y <= 64) { fp_mul_comba64(A,B,C); return; } #endif fp_mul_comba(A,B,C); } /* $Source$ */ /* $Revision$ */ /* $Date$ */