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);
}
int cpModInv_BNU(BNU_CHUNK_T* pInv,
const BNU_CHUNK_T* pA, cpSize nsA,
const BNU_CHUNK_T* pM, cpSize nsM,
BNU_CHUNK_T* bufInv, BNU_CHUNK_T* bufA, BNU_CHUNK_T* bufM)
{
FIX_BNU(pA, nsA);
FIX_BNU(pM, nsM);
/* inv(1) = 1 */
if(nsA==1 && pA[0]==1) {
pInv[0] = 1;
return 1;
}
{
cpSize moduloSize = nsM;
BNU_CHUNK_T* X1 = pInv;
BNU_CHUNK_T* X2 = bufM;
BNU_CHUNK_T* Q = bufInv;
cpSize nsX1 = 1;
cpSize nsX2 = 1;
cpSize nsQ;
COPY_BNU(bufA, pA, nsA);
ZEXPAND_BNU(X1, 0, moduloSize);
ZEXPAND_BNU(X2, 0, moduloSize);
X2[0] = 1;
for(;;) {
nsM = cpDiv_BNU(Q, &nsQ, (BNU_CHUNK_T*)pM, nsM, bufA, nsA);
nsX1 = cpMac_BNU(X1,moduloSize, Q,nsQ, X2,nsX2);
if (nsM==1 && pM[0]==1) {
////ZEXPAND_BNU(X2, nsX2, moduloSize);
nsX2 = cpMac_BNU(X2,moduloSize, X1,nsX1, bufA, nsA);
COPY_BNU((BNU_CHUNK_T*)pM, X2, moduloSize);
cpSub_BNU(pInv, pM, X1, moduloSize);
FIX_BNU(pInv, moduloSize);
return moduloSize;
}
else if (nsM==1 && pM[0]==0) {
cpMul_BNU_school((BNU_CHUNK_T*)pM, X1,nsX1, bufA, nsA);
/* gcd = buf_a */
return 0;
}
nsA = cpDiv_BNU(Q, &nsQ, bufA, nsA, (BNU_CHUNK_T*)pM, nsM);
nsX2 = cpMac_BNU(X2,moduloSize, Q,nsQ, X1,nsX1);
if(nsA==1 && bufA[0]==1) {
////ZEXPAND_BNU(X1, nsX1, moduloSize);
nsX1 = cpMac_BNU(X1, moduloSize, X2, nsX2, pM, nsM);
COPY_BNU((BNU_CHUNK_T*)pM, X1, moduloSize);
COPY_BNU(pInv, X2, nsX2);
return nsX2;
}
else if (nsA==1 && bufA[0]==0) {
/* gcd = m */
COPY_BNU(X1, pM, nsM);
cpMul_BNU_school((BNU_CHUNK_T*)pM, X2, nsX2, X1, nsM);
return 0;
}
}
}
}
