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Potential fix for Montezuma Revenge segmentation fault #670

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Sebastian-Griesbach wants to merge 2 commits into from
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Potential fix for Montezuma Revenge segmentation fault #670

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277f3d6
Proposed fix for MontezumaRevenge segfault
Sebastian-Griesbach Feb 9, 2026
cc69f68
remove fix explanation in comments
Sebastian-Griesbach Feb 17, 2026
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31 changes: 7 additions & 24 deletions src/ale/emucore/TIA.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -2746,30 +2746,13 @@ void TIA::poke(uint16_t addr, uint8_t value)
myPOSM1 += ourCompleteMotionTable[x][myHMM1];
myPOSBL += ourCompleteMotionTable[x][myHMBL];

if(myPOSP0 >= 160)
myPOSP0 -= 160;
else if(myPOSP0 < 0)
myPOSP0 += 160;

if(myPOSP1 >= 160)
myPOSP1 -= 160;
else if(myPOSP1 < 0)
myPOSP1 += 160;

if(myPOSM0 >= 160)
myPOSM0 -= 160;
else if(myPOSM0 < 0)
myPOSM0 += 160;

if(myPOSM1 >= 160)
myPOSM1 -= 160;
else if(myPOSM1 < 0)
myPOSM1 += 160;

if(myPOSBL >= 160)
myPOSBL -= 160;
else if(myPOSBL < 0)
myPOSBL += 160;
// Normalize all positions to valid range [0, 159] using modular arithmetic
myPOSP0 = ((myPOSP0 % 160) + 160) % 160;
myPOSP1 = ((myPOSP1 % 160) + 160) % 160;
myPOSM0 = ((myPOSM0 % 160) + 160) % 160;
myPOSM1 = ((myPOSM1 % 160) + 160) % 160;
myPOSBL = ((myPOSBL % 160) + 160) % 160;


myCurrentBLMask = &ourBallMaskTable[myPOSBL & 0x03]
[(myCTRLPF & 0x30) >> 4][160 - (myPOSBL & 0xFC)];
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