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IR: Implement FPRecipEstimate

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This commit is contained in:
MerryMage 2018-07-25 18:44:19 +01:00
parent c1dcfe29f7
commit fc2d33ae7b
1 changed files with 5 additions and 5 deletions
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10
src/common/fp/op/FPRecipEstimate.cpp
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@ -16,7 +16,6 @@
#include "common/fp/process_exception.h" #include "common/fp/process_exception.h"
#include "common/fp/process_nan.h" #include "common/fp/process_nan.h"
#include "common/fp/unpacked.h" #include "common/fp/unpacked.h"
#include "common/safe_ops.h"
namespace Dynarmic::FP { namespace Dynarmic::FP {
@ -91,9 +90,9 @@ FPT FPRecipEstimate(FPT op, FPCR fpcr, FPSR& fpsr) {
} }
} }
const u64 scaled = Safe::LogicalShiftRight(value.mantissa, normalized_point_position - 8); const u64 scaled = value.mantissa >> (normalized_point_position - 8);
u64 estimate = static_cast<u64>(RecipEstimate(scaled)) << (FPInfo<FPT>::explicit_mantissa_width - 8); u64 estimate = static_cast<u64>(RecipEstimate(scaled)) << (FPInfo<FPT>::explicit_mantissa_width - 8);
int result_exponent = -value.exponent; int result_exponent = -(value.exponent + 1);
if (result_exponent < FPInfo<FPT>::exponent_min) { if (result_exponent < FPInfo<FPT>::exponent_min) {
switch (result_exponent) { switch (result_exponent) {
case (FPInfo<FPT>::exponent_min - 1): case (FPInfo<FPT>::exponent_min - 1):
@ -103,16 +102,17 @@ FPT FPRecipEstimate(FPT op, FPCR fpcr, FPSR& fpsr) {
case (FPInfo<FPT>::exponent_min - 2): case (FPInfo<FPT>::exponent_min - 2):
estimate |= FPInfo<FPT>::implicit_leading_bit; estimate |= FPInfo<FPT>::implicit_leading_bit;
estimate >>= 2; estimate >>= 2;
result_exponent = 0; result_exponent++;
break; break;
default: default:
UNREACHABLE(); UNREACHABLE();
} }
} }
const FPT bits_sign = FPInfo<FPT>::Zero(sign);
const FPT bits_exponent = static_cast<FPT>(result_exponent + FPInfo<FPT>::exponent_bias); const FPT bits_exponent = static_cast<FPT>(result_exponent + FPInfo<FPT>::exponent_bias);
const FPT bits_mantissa = static_cast<FPT>(estimate); const FPT bits_mantissa = static_cast<FPT>(estimate);
return (bits_exponent << FPInfo<FPT>::explicit_mantissa_width) | (bits_mantissa & FPInfo<FPT>::mantissa_mask); return (bits_exponent << FPInfo<FPT>::explicit_mantissa_width) | (bits_mantissa & FPInfo<FPT>::mantissa_mask) | bits_sign;
} }
template u32 FPRecipEstimate<u32>(u32 op, FPCR fpcr, FPSR& fpsr); template u32 FPRecipEstimate<u32>(u32 op, FPCR fpcr, FPSR& fpsr);