fp_mul64
fp_mul64(dest->mant.m32[0], dest->mant.m32[1],
fp_mul64(dest->m32[0], dest->m32[1], src1->mant.m32[0], src2->mant.m32[0]);
fp_mul64(dest->m32[2], dest->m32[3], src1->mant.m32[1], src2->mant.m32[1]);
fp_mul64(temp.m32[0], temp.m32[1], src1->mant.m32[0], src2->mant.m32[1]);
fp_mul64(temp.m32[0], temp.m32[1], src1->mant.m32[1], src2->mant.m32[0]);
fp_mul64(*mantp, dummy, first, fix);
fp_mul64(*mantp, dummy, first, fix);
fp_mul64(tmp.m32[0], tmp.m32[1], div->mant.m32[0], first - *mantp);
fp_mul64(tmp64.m32[0], tmp64.m32[1], *mantp, div->mant.m32[1]);