void gcry_mpi_mul_ui( gcry_mpi_t prod, gcry_mpi_t mult, unsigned long small_mult ) { mpi_size_t size, prod_size; mpi_ptr_t prod_ptr; mpi_limb_t cy; int sign; size = mult->nlimbs; sign = mult->sign; if( !size || !small_mult ) { prod->nlimbs = 0; prod->sign = 0; return; } prod_size = size + 1; if( prod->alloced < prod_size ) mpi_resize( prod, prod_size ); prod_ptr = prod->d; cy = _gcry_mpih_mul_1( prod_ptr, mult->d, size, (mpi_limb_t)small_mult ); if( cy ) prod_ptr[size++] = cy; prod->nlimbs = size; prod->sign = sign; }
mpi_limb_t _gcry_mpih_mul( mpi_ptr_t prodp, mpi_ptr_t up, mpi_size_t usize, mpi_ptr_t vp, mpi_size_t vsize) { mpi_ptr_t prod_endp = prodp + usize + vsize - 1; mpi_limb_t cy; struct karatsuba_ctx ctx; if( vsize < KARATSUBA_THRESHOLD ) { mpi_size_t i; mpi_limb_t v_limb; if( !vsize ) return 0; /* Multiply by the first limb in V separately, as the result can be * stored (not added) to PROD. We also avoid a loop for zeroing. */ v_limb = vp[0]; if( v_limb <= 1 ) { if( v_limb == 1 ) MPN_COPY( prodp, up, usize ); else MPN_ZERO( prodp, usize ); cy = 0; } else cy = _gcry_mpih_mul_1( prodp, up, usize, v_limb ); prodp[usize] = cy; prodp++; /* For each iteration in the outer loop, multiply one limb from * U with one limb from V, and add it to PROD. */ for( i = 1; i < vsize; i++ ) { v_limb = vp[i]; if( v_limb <= 1 ) { cy = 0; if( v_limb == 1 ) cy = _gcry_mpih_add_n(prodp, prodp, up, usize); } else cy = _gcry_mpih_addmul_1(prodp, up, usize, v_limb); prodp[usize] = cy; prodp++; } return cy; } memset( &ctx, 0, sizeof ctx ); _gcry_mpih_mul_karatsuba_case( prodp, up, usize, vp, vsize, &ctx ); _gcry_mpih_release_karatsuba_ctx( &ctx ); return *prod_endp; }
static mpi_limb_t mul_n_basecase( mpi_ptr_t prodp, mpi_ptr_t up, mpi_ptr_t vp, mpi_size_t size) { mpi_size_t i; mpi_limb_t cy; mpi_limb_t v_limb; /* Multiply by the first limb in V separately, as the result can be * stored (not added) to PROD. We also avoid a loop for zeroing. */ v_limb = vp[0]; if( v_limb <= 1 ) { if( v_limb == 1 ) MPN_COPY( prodp, up, size ); else MPN_ZERO( prodp, size ); cy = 0; } else cy = _gcry_mpih_mul_1( prodp, up, size, v_limb ); prodp[size] = cy; prodp++; /* For each iteration in the outer loop, multiply one limb from * U with one limb from V, and add it to PROD. */ for( i = 1; i < size; i++ ) { v_limb = vp[i]; if( v_limb <= 1 ) { cy = 0; if( v_limb == 1 ) cy = _gcry_mpih_add_n(prodp, prodp, up, size); } else cy = _gcry_mpih_addmul_1(prodp, up, size, v_limb); prodp[size] = cy; prodp++; } return cy; }