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Fix division edge cases and prevent crash

This commit is contained in:
Kellan Clark 2022-10-23 20:22:21 -04:00
parent 739f3162d5
commit b5b7f29255
1 changed files with 15 additions and 2 deletions
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15
desmume/src/MMU.cpp
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@ -1068,7 +1068,6 @@ static void execsqrt() {
}
static void execdiv() {
s64 num,den;
s64 res,mod;
u8 mode = MMU_new.div.mode;
@ -1101,10 +1100,24 @@ static void execdiv() {
res = ((num < 0) ? 1 : -1);
mod = num;
// when the result is 32bits, the upper 32bits of the sign-extended result are inverted
if (mode == 0)
res ^= 0xFFFFFFFF00000000;
// the DIV0 flag in DIVCNT is set only if the full 64bit DIV_DENOM value is zero, even in 32bit mode
if ((u64)T1ReadQuad(MMU.ARM9_REG, 0x298) == 0)
MMU_new.div.div0 = 1;
}
else if((mode != 0) && (num == 0x8000000000000000) && (den == -1))
{
res = 0x8000000000000000;
mod = 0;
}
else if((mode == 0) && (num == (s64) (s32) 0x80000000) && (den == -1))
{
res = 0x80000000;
mod = 0;
}
else
{
res = num / den;