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poweropcodes: Fix divs. 

dividend and divisor are supposed to be a twos compliment numbers.
Fix OV calculation. Previously, it was using power_setsoov which I think is only for add and subtract operations.
Fix CR calculation. It depends on the remainder, not the quotient.
This commit is contained in:
joevt 2024-04-09 01:31:09 -07:00 committed by dingusdev
parent 88aa249ce1
commit 0d1ce68d19
1 changed files with 20 additions and 5 deletions
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25
cpu/ppc/poweropcodes.cpp
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@ -140,16 +140,31 @@ template void dppc_interpreter::power_div<RC1, OV1>();
template <field_rc rec, field_ov ov>
void dppc_interpreter::power_divs() {
uint32_t ppc_result_d;
int32_t remainder;
ppc_grab_regsdab(ppc_cur_instruction);
uint32_t ppc_result_d = ppc_result_a / ppc_result_b;
ppc_state.spr[SPR::MQ] = (ppc_result_a % ppc_result_b);
if (ov)
power_setsoov(ppc_result_b, ppc_result_a, ppc_result_d);
if (!ppc_result_b) { // handle the "anything / 0" case
ppc_result_d = -1;
remainder = ppc_result_a;
if (ov)
ppc_state.spr[SPR::XER] |= XER::SO | XER::OV;
} else if (ppc_result_a == 0x80000000U && ppc_result_b == 0xFFFFFFFFU) {
ppc_result_d = 0x80000000U;
remainder = 0;
if (ov)
ppc_state.spr[SPR::XER] |= XER::SO | XER::OV;
} else { // normal signed devision
ppc_result_d = int32_t(ppc_result_a) / int32_t(ppc_result_b);
remainder = (int32_t(ppc_result_a) % int32_t(ppc_result_b));
if (ov)
ppc_state.spr[SPR::XER] &= ~XER::OV;
}
if (rec)
ppc_changecrf0(ppc_result_d);
ppc_changecrf0(remainder);
ppc_store_iresult_reg(reg_d, ppc_result_d);
ppc_state.spr[SPR::MQ] = remainder;
}
template void dppc_interpreter::power_divs<RC0, OV0>();