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Shader interpreter: Fix out-of-bounds float uniform edge cases

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wheremyfoodat 2025-07-23 02:50:06 +03:00
commit 945ac26b0b
1 changed files with 14 additions and 6 deletions
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20
src/core/PICA/shader_interpreter.cpp
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@ -124,16 +124,24 @@ u8 PICAShader::getIndexedSource(u32 source, u32 index) {
switch (index) {
// No offset applied
case 0: [[likely]] return u8(source);
// Address register
// An address register (if index == 1 or 2) or the loop counter (if index == 3) is used as the offset
// There's several edge cases to handle, which have been verified with our shader tests and on a real 3DS
case 1:
case 2: {
const s32 offset = addrRegister[index - 1];
case 2:
case 3: {
s32 offset = (index == 3) ? s32(loopCounter) : addrRegister[index - 1];
if (offset < -128 || offset > 127) [[unlikely]] {
return u8(source);
offset = 0;
}
return u8(source + offset);
// Subtract 0x20 to get the index of the float uniform. Add the offset to it, then mask the sum with 0x7F like the PICA does
// After that, add 0x20 again to undo the initial subtraction
u8 floatUniformIndex = u8(((source - 0x20) + offset) & 0x7F);
floatUniformIndex += 0x20;
return floatUniformIndex;
}
case 3: return u8(source + loopCounter);
}
Helpers::panic("Reached unreachable path in PICAShader::getIndexedSource");