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DSPLLE minor clean

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git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@3816 8ced0084-cf51-0410-be5f-012b33b47a6e
This commit is contained in:
nakeee 2009-07-16 10:25:27 +00:00
parent 4212773b1b
commit 18e45baafc
1 changed files with 9 additions and 21 deletions
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30
Source/Core/DSPCore/Src/DspIntMisc.cpp
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@ -42,6 +42,7 @@ void mrr(const UDSPInstruction& opc)
u16 val = dsp_op_read_reg(sreg);
dsp_op_write_reg(dreg, val);
dsp_conditional_extend_accum(dreg);
}
// LRI $D, #I
@ -50,9 +51,10 @@ void mrr(const UDSPInstruction& opc)
// Load immediate value I to register $D.
// FIXME: Perform additional operation depending on destination register.
// DSPSpy discovery: This, and possibly other instructions that load a register,
// has a different behaviour in S40 mode if loaded to AC0.M: The value gets sign extended
// to the whole accumulator! This does not happen in S16 mode.
// DSPSpy discovery: This, and possibly other instructions that load a
// register, has a different behaviour in S40 mode if loaded to AC0.M: The
// value gets sign extended to the whole accumulator! This does not happen in
// S16 mode.
void lri(const UDSPInstruction& opc)
{
u8 reg = opc.hex & DSP_REG_MASK;
@ -95,8 +97,6 @@ void addarn(const UDSPInstruction& opc)
u8 dreg = opc.hex & 0x3;
u8 sreg = (opc.hex >> 2) & 0x3;
// g_dsp.r[dreg] += (s16)g_dsp.r[DSP_REG_IX0 + sreg];
dsp_increase_addr_reg(dreg, (s16)g_dsp.r[DSP_REG_IX0 + sreg]);
// It is critical for the Zelda ucode that this one wraps correctly.
@ -149,24 +149,13 @@ void sbset(const UDSPInstruction& opc)
}
// FIXME inside
// This is a bunch of flag setters, flipping bits in SR. So far so good,
// but it's harder to know exactly what effect they have.
// M0/M2 change the multiplier mode (it can multiply by 2 for free).
//
// SET16 changes something very important: see the LRI instruction above.
// Hermes' demo sets the following defaults:
// SET40
// CLR15
// M0
void srbith(const UDSPInstruction& opc)
{
switch ((opc.hex >> 8) & 0xf)
{
// M0 seems to be the default. M2 is used in functions in Zelda
// and then reset with M0 at the end. Like the other bits here, it's
// done around loops with lots of multiplications.
// I've confirmed with DSPSpy that they flip this bit.
// M0/M2 change the multiplier mode (it can multiply by 2 for free).
case 0xa: // M2
g_dsp.r[DSP_REG_SR] &= ~SR_MUL_MODIFY;
break;
@ -184,13 +173,12 @@ void srbith(const UDSPInstruction& opc)
break;
// Automatic 40-bit sign extension when loading ACx.M.
// 40 seems to be the default.
// Confirmed these by using DSPSpy and copying the value of SR to R00 after setting.
case 0xe: // SET16 (really, clear SR's 0x4000)
// SET40 changes something very important: see the LRI instruction above.
case 0xe: // SET16 (CLR40)
g_dsp.r[DSP_REG_SR] &= ~SR_40_MODE_BIT;
break;
case 0xf: // SET40 (really, set SR's 0x4000)
case 0xf: // SET40
g_dsp.r[DSP_REG_SR] |= SR_40_MODE_BIT;
break;