SwitchEmu/dynarmic
1
0
Fork 0
mirror of https://git.suyu.dev/suyu/dynarmic.git synced 2026-03-25 20:28:43 +00:00
Code Issues Packages Projects Releases Wiki Activity

fp: Change FPUnpacked to a normalized representation

Browse Source 
Having a known position for the highest set bit makes writing algorithms easier
This commit is contained in:
MerryMage
2018-07-25 17:39:14 +01:00
parent 680395a803
commit 7a673a8a43
10 changed files with 71 additions and 56 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
src/common/fp/unpacked.h
View File

@@ -24,7 +24,10 @@ enum class FPType {
SNaN,
};
/// value = (sign ? -1 : +1) * mantissa * 2^exponent
constexpr size_t normalized_point_position = 62;
/// value = (sign ? -1 : +1) * mantissa/(2^62) * 2^exponent
/// 63rd bit of mantissa is always set (unless value is zero)
struct FPUnpacked {
bool sign;
int exponent;
@@ -35,6 +38,19 @@ inline bool operator==(const FPUnpacked& a, const FPUnpacked& b) {
return std::tie(a.sign, a.exponent, a.mantissa) == std::tie(b.sign, b.exponent, b.mantissa);
}
/// return value = (sign ? -1 : +1) * value * 2^exponent
constexpr FPUnpacked ToNormalized(bool sign, int exponent, u64 value) {
if (value == 0) {
return {sign, 0, 0};
}
const int highest_bit = Common::HighestSetBit(value);
const int offset = static_cast<int>(normalized_point_position) - highest_bit;
value <<= offset;
exponent -= offset - normalized_point_position;
return {sign, exponent, value};
}
template<typename FPT>
std::tuple<FPType, bool, FPUnpacked> FPUnpack(FPT op, FPCR fpcr, FPSR& fpsr);