int main() {
const ssize_t A = 3;
const size_t Awidth = 2;
const size_t Dwidth = 4;
const ssize_t Dmin = (-1) * (1ll << (Dwidth - 1));
const ssize_t Dmax = (1ll << (Dwidth - 1)) - 1;
const ssize_t Cwidth = Awidth + Dwidth;
const ssize_t AInv = ext_euklidean(A, Cwidth) & ((1ll << Cwidth) - 1);
const size_t numCodewords = (1ull << Cwidth);
std::cout << "numCodewords: " << numCodewords << std::endl;
const size_t numMasks = numCodewords / (sizeof(int) * 4); // How many masks will we generate?
int * pNonCodewordMasks = new int[numMasks];
const int16_t c = ~((1ll << (Cwidth - 1)) - 1);
std::cout << "c = 0x" << std::hex << c << std::dec << std::endl;
for (ssize_t i = 0, cw = c, posMask = 0; i < numCodewords; ++posMask) {
int tmpMask = 0;
for (ssize_t k = 0; k < 16; ++k, ++cw, ++i) {
if ((cw % A) != 0) { // we want the non-codewords
// std::cout << "cw % A != 0: " << cw << std::endl;
tmpMask |= (1ll << (k * 2)) | (1ll << (k * 2 + 1)); // expand to 32 bits, because AVX2 cannot movemask across lanes to 16 bits
}
}
pNonCodewordMasks[posMask] = tmpMask;
}
std::cout << "numMasks: " << numMasks << std::endl;
std::cout << "non-codeword-masks: 0x" << std::hex << std::setfill('0');
for (size_t posMask = 0; posMask < numMasks; ++posMask) {
std::cout << std::setw(8) << pNonCodewordMasks[posMask] << ':';
}
std::cout << std::dec << std::endl << std::setfill(' ');
auto mmCodewords = _mm256_set_epi16(c+15, c+14, c+13, c+12, c+11, c+10, c+9, c+8, c+7, c+6, c+5, c+4, c+3, c+2, c+1, c);
auto mmAddUp = _mm256_set1_epi16(16);
auto mmAinv = _mm256_set1_epi16(AInv);
auto mmDmin = _mm256_set1_epi16(Dmin);
auto mmDmax = _mm256_set1_epi16(Dmax);
const size_t posEnd = (1ull << Cwidth);
__m256i mmFillUp[] = {_mm256_set1_epi16(0), _mm256_set1_epi16(~((1ll << Cwidth) - 1))}; // fill up all non-codeword bits with 1's if necessary
std::cout << "posEnd = 0x" << std::hex << posEnd << std::dec << std::endl;
std::cout << std::setfill('0') << std::hex;
for(size_t pos = 15, posMask = 0; pos < posEnd; pos += 16, ++posMask) {
auto isNeg = 0x1 & _mm256_movemask_epi8(_mm256_cmpgt_epi16(mmFillUp[0], mmCodewords));
auto mm1 = _mm256_or_si256(_mm256_mullo_epi16(mmCodewords, mmAinv), mmFillUp[isNeg]);
auto mm2 = _mm256_cmpgt_epi16(mm1, mmDmin);
auto mm3 = _mm256_cmpgt_epi16(mmDmax, mm1);
auto mm4 = _mm256_cmpeq_epi16(mmDmax, mm1);
auto mm5 = _mm256_or_si256(mm3, mm4);
auto mm6 = _mm256_and_si256(mm2, mm5);
auto mask = _mm256_movemask_epi8(mm6);
if (mask & pNonCodewordMasks[posMask]) {
std::cout << "BAD @0x" << std::setw((Cwidth + 7) / 8) << pos << ": 0x" << mask << " & 0x" << pNonCodewordMasks[posMask] << " = 0x" << (mask & pNonCodewordMasks[posMask]) << std::endl;
} else {
std::cout << "OK @0x" << std::setw((Cwidth + 7) / 8) << pos << ": 0x" << mask << " & 0x" << pNonCodewordMasks[posMask] << " = 0x" << (mask & pNonCodewordMasks[posMask]) << std::endl;
}
mmCodewords = _mm256_add_epi16(mmCodewords, mmAddUp);
}
std::cout << std::setfill(' ') << std::dec;
}
__m256i test_mm256_cmpeq_epi16(__m256i a, __m256i b) {
// CHECK: icmp eq <16 x i16>
return _mm256_cmpeq_epi16(a, b);
}
