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;
}
