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DSP: minor shift instruction tweaks. that stuff about negated shift amount in the comments is spooky though. gonna have to run some test code. 

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@2906 8ced0084-cf51-0410-be5f-012b33b47a6e
This commit is contained in:
hrydgard 2009-04-06 19:57:54 +00:00
parent 215e014515
commit 957127d505
1 changed files with 7 additions and 6 deletions
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13
Source/Plugins/Plugin_DSP_LLE-testing/Src/DSPInterpreter.cpp
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@ -1091,7 +1091,7 @@ void asr16(const UDSPInstruction& opc)
void lsl(const UDSPInstruction& opc) void lsl(const UDSPInstruction& opc)
{ {
u16 shift = opc.ushift; u16 shift = opc.ushift;
s64 acc = dsp_get_long_acc(opc.areg); u64 acc = dsp_get_long_acc(opc.areg);
acc <<= shift; acc <<= shift;
dsp_set_long_acc(opc.areg, acc); dsp_set_long_acc(opc.areg, acc);
@ -1106,10 +1106,11 @@ void lsl(const UDSPInstruction& opc)
void lsr(const UDSPInstruction& opc) void lsr(const UDSPInstruction& opc)
{ {
u16 shift = -opc.ushift; u16 shift = -opc.ushift;
s64 acc = dsp_get_long_acc(opc.areg); u64 acc = dsp_get_long_acc(opc.areg);
// Lop off the extraneous sign extension our 64-bit fake accum causes
acc &= 0x000000FFFFFFFFFF;
acc >>= shift; acc >>= shift;
dsp_set_long_acc(opc.areg, acc); dsp_set_long_acc(opc.areg, (s64)acc);
Update_SR_Register64(acc); Update_SR_Register64(acc);
} }
@ -1122,7 +1123,7 @@ void asl(const UDSPInstruction& opc)
u16 shift = opc.ushift; u16 shift = opc.ushift;
// arithmetic shift // arithmetic shift
s64 acc = dsp_get_long_acc(opc.areg); u64 acc = dsp_get_long_acc(opc.areg);
acc <<= shift; acc <<= shift;
dsp_set_long_acc(opc.areg, acc); dsp_set_long_acc(opc.areg, acc);
@ -1132,7 +1133,7 @@ void asl(const UDSPInstruction& opc)
// ASR $acR, #I // ASR $acR, #I
// 0001 010r 11ii iiii // 0001 010r 11ii iiii
// Arithmetically shifts left accumulator $acR by number specified by // Arithmetically shifts right accumulator $acR by number specified by
// value calculated by negating sign extended bits 0-6. // value calculated by negating sign extended bits 0-6.
void asr(const UDSPInstruction& opc) void asr(const UDSPInstruction& opc)