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poweropcodes: Fix div.

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dividend is supposed to be a twos compliment number.
Fix test for dividend = -0x80000000 and divisor = -1. Previously, the test was assuming dividend was a 32-bit value from rA.
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 01:25:23 -07:00 committed by dingusdev
parent ff626ae0b5
commit 88aa249ce1
1 changed files with 26 additions and 10 deletions
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34
cpu/ppc/poweropcodes.cpp
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@ -98,23 +98,39 @@ void dppc_interpreter::power_div() {
uint32_t ppc_result_d;
ppc_grab_regsdab(ppc_cur_instruction);
uint64_t dividend = ((uint64_t)ppc_result_a << 32) | ppc_state.spr[SPR::MQ];
int64_t dividend = (uint64_t(ppc_result_a) << 32) | ppc_state.spr[SPR::MQ];
int32_t divisor = ppc_result_b;
int64_t quotient;
int32_t remainder;
if ((ppc_result_a == 0x80000000UL && divisor == -1) || !divisor) {
ppc_state.spr[SPR::MQ] = 0;
ppc_result_d = 0x80000000UL; // -2^31 aka INT32_MIN
if (dividend == -0x80000000 && divisor == -1) {
remainder = 0;
ppc_result_d = 0x80000000U; // -2^31 aka INT32_MIN
if (ov)
ppc_state.spr[SPR::XER] |= XER::SO | XER::OV;
} else if (!divisor) {
remainder = 0;
ppc_result_d = 0x80000000U; // -2^31 aka INT32_MIN
if (ov)
ppc_state.spr[SPR::XER] |= XER::SO | XER::OV;
} else {
ppc_result_d = uint32_t(dividend / divisor);
ppc_state.spr[SPR::MQ] = dividend % divisor;
quotient = dividend / divisor;
remainder = dividend % divisor;
ppc_result_d = uint32_t(quotient);
if (ov) {
if (((quotient >> 31) + 1) & ~1) {
ppc_state.spr[SPR::XER] |= XER::SO | XER::OV;
} else {
ppc_state.spr[SPR::XER] &= ~XER::OV;
}
}
}
if (ov)
power_setsoov(ppc_result_b, ppc_result_a, ppc_result_d);
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_div<RC0, OV0>();