void cpMontRedAdc_BNU(BNU_CHUNK_T* pR,
BNU_CHUNK_T* pProduct,
const BNU_CHUNK_T* pModulus, cpSize nsM, BNU_CHUNK_T m0)
{
BNU_CHUNK_T carry;
BNU_CHUNK_T extension;
cpSize n;
for(n=0, carry = 0; n<(nsM-1); n++) {
BNU_CHUNK_T u = pProduct[n]*m0;
BNU_CHUNK_T t = pProduct[nsM +n +1] + carry;
extension = cpAddMulDgt_BNU(pProduct+n, pModulus, nsM, u);
ADD_AB(carry, pProduct[nsM+n], pProduct[nsM+n], extension);
t += carry;
carry = t<pProduct[nsM+n+1];
pProduct[nsM+n+1] = t;
}
m0 *= pProduct[nsM-1];
extension = cpAddMulDgt_BNU(pProduct+nsM-1, pModulus, nsM, m0);
ADD_AB(extension, pProduct[2*nsM-1], pProduct[2*nsM-1], extension);
carry |= extension;
carry -= cpSub_BNU(pR, pProduct+nsM, pModulus, nsM);
/* condition copy: R = carry? Product+mSize : R */
MASKED_COPY_BNU(pR, carry, pProduct+nsM, pR, nsM);
}
/*
// cpMAC_BNU
//
// Multiply with ACcumulation
// Computes r <- r + a * b, returns real size of the r in the size_r variable
// Returns 0 if there are no enought buffer size to write to r[MAX(size_r + 1, size_a + size_b) - 1]
// Returns 1 if no error
//
// Note:
// DO NOT run in inplace mode
// The minimum buffer size for the r must be (size_a + size_b - 1)
// the maximum buffer size for the r is MAX(size_r + 1, size_a + size_b)
*/
static int cpMac_BNU(BNU_CHUNK_T* pR, cpSize nsR,
const BNU_CHUNK_T* pA, cpSize nsA,
const BNU_CHUNK_T* pB, cpSize nsB)
{
/* cleanup the rest of destination buffer */
ZEXPAND_BNU(pR, nsR, nsA+nsB-1);
{
BNU_CHUNK_T expansion = 0;
cpSize i;
for(i=0; i<nsB && !expansion; i++) {
expansion = cpAddMulDgt_BNU(pR+i, pA, nsA, pB[i]);
if(expansion)
expansion = cpInc_BNU(pR+i+nsA, pR+i+nsA, nsR-i-nsA, expansion);
}
if(expansion)
return 0;
else { /* compute real size */
FIX_BNU(pR, nsR);
return nsR;
}
}
}
