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feat(big): add Mul

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fallenoak 2023-01-29 22:59:28 -06:00 • committed by GitHub
parent 33585cb36f
commit e74654800d
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3 changed files with 75 additions and 0 deletions
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13
storm/big/Ops.cpp
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@ -49,6 +49,19 @@ uint64_t MakeLarge(uint32_t low, uint32_t high) {
return low + (static_cast<uint64_t>(high) << 32);
}
void Mul(BigBuffer& a, const BigBuffer& b, uint64_t c) {
// TODO assertion c <= SMALL_BOUND
uint64_t carry = 0;
uint32_t i = 0;
for (i = 0; carry || b.IsUsed(i); i++) {
carry += b[i] * c;
a[i] = ExtractLowPart(carry);
}
a.SetCount(i);
}
void ToBinaryAppend(TSGrowableArray<uint8_t>& output, const BigBuffer& buffer) {
for (uint32_t i = 0; i < buffer.Count() * 4; i++) {
auto byte = buffer[i / 4] >> (8 * (i & 3));

2
storm/big/Ops.hpp
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@ -16,6 +16,8 @@ void FromUnsigned(BigBuffer& buffer, uint32_t value);
uint64_t MakeLarge(uint32_t low, uint32_t high);
void Mul(BigBuffer& a, const BigBuffer& b, uint64_t c);
void ToBinary(TSGrowableArray<uint8_t>& output, const BigBuffer& buffer);
#endif