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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
View file

@ -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

125
test/Big.cpp
View file

@ -583,6 +583,31 @@ TEST_CASE("SBigMul", "[big]") {
}
}
TEST_CASE("SBigSub", "[big]") {
SECTION("subtracts 1 from 2") {
BigData* a;
SBigNew(&a);
BigData* b;
SBigNew(&b);
SBigFromUnsigned(b, 2);
BigData* c;
SBigNew(&c);
SBigFromUnsigned(c, 1);
SBigSub(a, b, c);
a->Primary().Trim();
CHECK(a->Primary().Count() == 1);
CHECK(a->Primary()[0] == 1);
SBigDel(a);
SBigDel(b);
}
}
TEST_CASE("SBigToBinaryBuffer", "[big]") {
SECTION("returns expected buffer for bigdata representing 0") {
BigData* num;
@ -663,3 +688,103 @@ TEST_CASE("SetZero", "[big]") {
SBigDel(num);
}
}
TEST_CASE("Sub", "[big]") {
SECTION("subtracts 0 from 1") {
BigData* a;
SBigNew(&a);
BigData* b;
SBigNew(&b);
SBigFromUnsigned(b, 1);
BigData* c;
SBigNew(&c);
SBigFromUnsigned(c, 0);
Sub(a->Primary(), b->Primary(), c->Primary());
a->Primary().Trim();
CHECK(a->Primary().Count() == 1);
CHECK(a->Primary()[0] == 1);
SBigDel(a);
SBigDel(b);
}
SECTION("subtracts 1 from 2") {
BigData* a;
SBigNew(&a);
BigData* b;
SBigNew(&b);
SBigFromUnsigned(b, 2);
BigData* c;
SBigNew(&c);
SBigFromUnsigned(c, 1);
Sub(a->Primary(), b->Primary(), c->Primary());
a->Primary().Trim();
CHECK(a->Primary().Count() == 1);
CHECK(a->Primary()[0] == 1);
SBigDel(a);
SBigDel(b);
}
SECTION("subtracts 0x1111111111111111 from 0x9999999999999999") {
BigData* a;
SBigNew(&a);
BigData* b;
SBigNew(&b);
uint64_t b_ = 0x9999999999999999;
SBigFromBinary(b, reinterpret_cast<uint8_t*>(&b_), sizeof(b_));
BigData* c;
SBigNew(&c);
uint64_t c_ = 0x1111111111111111;
SBigFromBinary(c, reinterpret_cast<uint8_t*>(&c_), sizeof(c_));
Sub(a->Primary(), b->Primary(), c->Primary());
a->Primary().Trim();
CHECK(a->Primary().Count() == 2);
CHECK(a->Primary()[0] == 0x88888888);
CHECK(a->Primary()[1] == 0x88888888);
SBigDel(a);
SBigDel(b);
}
SECTION("subtracts 0x123456789ABCDEF0 from 0xFEDCBA9876543210") {
BigData* a;
SBigNew(&a);
BigData* b;
SBigNew(&b);
uint64_t b_ = 0xFEDCBA9876543210;
SBigFromBinary(b, reinterpret_cast<uint8_t*>(&b_), sizeof(b_));
BigData* c;
SBigNew(&c);
uint64_t c_ = 0x123456789ABCDEF0;
SBigFromBinary(c, reinterpret_cast<uint8_t*>(&c_), sizeof(c_));
Sub(a->Primary(), b->Primary(), c->Primary());
a->Primary().Trim();
CHECK(a->Primary().Count() == 2);
CHECK(a->Primary()[0] == 0xDB975320);
CHECK(a->Primary()[1] == 0xECA8641F);
SBigDel(a);
SBigDel(b);
}
}