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feat(big): add SBigSub

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fallenoak 2023-02-01 21:29:16 -06:00
parent 6e62f0a604
commit 5d875631a6
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5 changed files with 146 additions and 0 deletions
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4
storm/Big.cpp
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@ -28,6 +28,10 @@ void SBigMul(BigData* a, BigData* b, BigData* c) {
Mul(a->Primary(), b->Primary(), c->Primary(), a->Stack());
}
void SBigSub(BigData* a, BigData* b, BigData* c) {
Sub(a->Primary(), b->Primary(), c->Primary());
}
void SBigToBinaryBuffer(BigData* num, uint8_t* data, uint32_t maxBytes, uint32_t* bytes) {
auto& output = num->Output();
ToBinary(output, num->Primary());

2
storm/Big.hpp
View file

@ -16,6 +16,8 @@ void SBigMul(BigData* a, BigData* b, BigData* c);
void SBigNew(BigData** num);
void SBigSub(BigData* a, BigData* b, BigData* c);
void SBigToBinaryBuffer(BigData* num, uint8_t* data, uint32_t maxBytes, uint32_t* bytes);
#endif

13
storm/big/Ops.cpp
View file

@ -141,6 +141,19 @@ void SetZero(BigBuffer& buffer) {
buffer.Clear();
}
void Sub(BigBuffer& a, const BigBuffer& b, const BigBuffer& c) {
uint64_t borrow = 0;
uint32_t i = 0;
for (i = 0; b.IsUsed(i) || c.IsUsed(i); i++) {
borrow += b[i] - static_cast<uint64_t>(c[i]);
a[i] = ExtractLowPartSx(borrow);
}
a.SetCount(i);
STORM_ASSERT(!borrow);
}
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
View file

@ -31,6 +31,8 @@ void SetOne(BigBuffer& buffer);
void SetZero(BigBuffer& buffer);
void Sub(BigBuffer& a, const BigBuffer& b, const BigBuffer& c);
void ToBinary(TSGrowableArray<uint8_t>& output, const BigBuffer& buffer);
#endif