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ppcopcodes: Fix lswx.

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- Remove invalid form check unless you know for sure it's supposed to cause an exception.
- Add register skip for 601 CPU. This needs testing.
This commit is contained in:
joevt 2024-01-10 05:54:51 -08:00 committed by Maxim Poliakovski
parent 1fc551fae0
commit 8764beba39
1 changed files with 24 additions and 21 deletions
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37
cpu/ppc/ppcopcodes.cpp
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@ -2118,38 +2118,41 @@ void dppc_interpreter::ppc_lswx() {
#endif
ppc_grab_regsdab();
/*
// Invalid instruction forms
if ((reg_d == 0 && reg_a == 0) || (reg_d == reg_a) || (reg_d == reg_b)) {
// UNTESTED! Does invalid form really cause exception?
// G4 doesn't do exception
ppc_exception_handler(Except_Type::EXC_PROGRAM, Exc_Cause::ILLEGAL_OP);
}
*/
ppc_effective_address = reg_a ? (ppc_result_a + ppc_result_b) : ppc_result_b;
uint32_t grab_inb = ppc_state.spr[SPR::XER] & 0x7F;
while (grab_inb >= 4) {
ppc_state.gpr[reg_d] = mmu_read_vmem<uint32_t>(ppc_effective_address);
reg_d++;
if (reg_d >= 32) { // wrap around through GPR0
reg_d = 0;
for (;;) {
if (is_601 && (reg_d == reg_b || (reg_a != 0 && reg_d == reg_a))) {
// UNTESTED! MPC601 manual is inconsistant on whether reg_b is skipped or not
reg_d = (reg_d + 1) & 31; // wrap around through GPR0
}
ppc_effective_address += 4;
grab_inb -= 4;
}
// handle remaining bytes
switch (grab_inb) {
case 0:
return;
case 1:
ppc_state.gpr[reg_d] = mmu_read_vmem<uint8_t>(ppc_effective_address) << 24;
break;
return;
case 2:
ppc_state.gpr[reg_d] = mmu_read_vmem<uint16_t>(ppc_effective_address) << 16;
break;
return;
case 3:
ppc_state.gpr[reg_d] = mmu_read_vmem<uint16_t>(ppc_effective_address) << 16;
ppc_state.gpr[reg_d] += mmu_read_vmem<uint8_t>(ppc_effective_address + 2) << 8;
break;
default:
break;
ppc_state.gpr[reg_d] = (mmu_read_vmem<uint16_t>(ppc_effective_address) << 16)
| (mmu_read_vmem<uint8_t>(ppc_effective_address + 2) << 8);
return;
}
ppc_state.gpr[reg_d] = mmu_read_vmem<uint32_t>(ppc_effective_address);
reg_d = (reg_d + 1) & 31; // wrap around through GPR0
ppc_effective_address += 4;
grab_inb -= 4;
}
}