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fp: Change FPUnpacked to a normalized representation

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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
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10
src/common/fp/unpacked.cpp
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@@ -35,20 +35,20 @@ std::tuple<FPType, bool, FPUnpacked> FPUnpack(FPT op, FPCR fpcr, FPSR& fpsr) {
return {FPType::Zero, sign, {sign, 0, 0}};
}
return {FPType::Nonzero, sign, {sign, denormal_exponent, frac_raw}};
return {FPType::Nonzero, sign, ToNormalized(sign, denormal_exponent, frac_raw)};
}
if (exp_raw == Common::Ones<FPT>(FPInfo<FPT>::exponent_width)) {
if (frac_raw == 0) {
return {FPType::Infinity, sign, {sign, 1000000, 1}};
return {FPType::Infinity, sign, ToNormalized(sign, 1000000, 1)};
}
const bool is_quiet = Common::Bit<mantissa_high_bit>(frac_raw);
return {is_quiet ? FPType::QNaN : FPType::SNaN, sign, {sign, 0, 0}};
}
const int exp = static_cast<int>(exp_raw) - FPInfo<FPT>::exponent_bias - FPInfo<FPT>::explicit_mantissa_width;
const u64 frac = frac_raw | FPInfo<FPT>::implicit_leading_bit;
const int exp = static_cast<int>(exp_raw) - FPInfo<FPT>::exponent_bias;
const u64 frac = static_cast<u64>(frac_raw | FPInfo<FPT>::implicit_leading_bit) << (normalized_point_position - FPInfo<FPT>::explicit_mantissa_width);
return {FPType::Nonzero, sign, {sign, exp, frac}};
}
@@ -61,7 +61,7 @@ std::tuple<bool, int, u64, ResidualError> Normalize(FPUnpacked op, int extra_rig
const int shift_amount = highest_set_bit - static_cast<int>(F) + extra_right_shift;
const u64 mantissa = Safe::LogicalShiftRight(op.mantissa, shift_amount);
const ResidualError error = ResidualErrorOnRightShift(op.mantissa, shift_amount);
const int exponent = op.exponent + highest_set_bit;
const int exponent = op.exponent + highest_set_bit - normalized_point_position;
return std::make_tuple(op.sign, exponent, mantissa, error);
}