thunderbrewhq/squall
1
0
Fork 0
mirror of https://github.com/thunderbrewhq/squall.git synced 2025-12-12 10:32:29 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

feat(big): add HighBitPos

Browse source
This commit is contained in:
fallenoak 2023-02-01 21:08:15 -06:00
parent e9d3284c70
commit 6e62f0a604
No known key found for this signature in database
GPG key ID: 7628F8E61AEA070D
3 changed files with 92 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

27
storm/big/Ops.cpp
View file

@ -68,6 +68,33 @@ void FromUnsigned(BigBuffer& buffer, uint32_t value) {
buffer.SetCount(1);
}
uint32_t HighBitPos(const BigBuffer& buffer) {
uint32_t index = buffer.Count();
if (index == 0) {
return 0;
}
while (buffer[--index] == 0) {
if (index == 0) {
return 0;
}
}
uint32_t mask = 0x80000000;
uint32_t bitIndex = 32;
while (bitIndex > 0) {
bitIndex--;
if (buffer[index] & mask) {
return (index * 32) + bitIndex;
}
mask >>= 1;
}
return 0;
}
uint64_t MakeLarge(uint32_t low, uint32_t high) {
return low + (static_cast<uint64_t>(high) << 32);
}

2
storm/big/Ops.hpp
View file

@ -19,6 +19,8 @@ void FromBinary(BigBuffer& buffer, const void* value, uint32_t bytes);
void FromUnsigned(BigBuffer& buffer, uint32_t value);
uint32_t HighBitPos(const BigBuffer& a);
uint64_t MakeLarge(uint32_t low, uint32_t high);
void Mul(BigBuffer& a, const BigBuffer& b, uint64_t c);

63
test/Big.cpp
View file

@ -200,6 +200,69 @@ TEST_CASE("ExtractLowPartSx", "[big]") {
}
}
TEST_CASE("HighBitPos", "[big]") {
SECTION("returns position of high bit for 0") {
BigData* num;
SBigNew(&num);
SBigFromUnsigned(num, 0);
CHECK(HighBitPos(num->Primary()) == 0);
SBigDel(num);
}
SECTION("returns position of high bit for 0x1000") {
BigData* num;
SBigNew(&num);
SBigFromUnsigned(num, 0x1000);
CHECK(HighBitPos(num->Primary()) == 12);
SBigDel(num);
}
SECTION("returns position of high bit for 0x1111") {
BigData* num;
SBigNew(&num);
SBigFromUnsigned(num, 0x1111);
CHECK(HighBitPos(num->Primary()) == 12);
SBigDel(num);
}
SECTION("returns position of high bit for 0xFFFF") {
BigData* num;
SBigNew(&num);
SBigFromUnsigned(num, 0xFFFF);
CHECK(HighBitPos(num->Primary()) == 15);
SBigDel(num);
}
SECTION("returns position of high bit for 0xFFFFFFFF") {
BigData* num;
SBigNew(&num);
SBigFromUnsigned(num, 0xFFFFFFFF);
CHECK(HighBitPos(num->Primary()) == 31);
SBigDel(num);
}
SECTION("returns position of high bit for 0x123456789ABCDEF0") {
BigData* num;
SBigNew(&num);
uint64_t data = 0x123456789ABCDEF0;
SBigFromBinary(num, reinterpret_cast<uint8_t*>(&data), sizeof(data));
CHECK(HighBitPos(num->Primary()) == 60);
SBigDel(num);
}
}
TEST_CASE("Mul", "[big]") {
SECTION("multiplies 0 and 1") {
BigData* a;