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VarAction2: Add checks for vars 7B, 7C when getting previous single load

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This commit is contained in:
Jonathan G Rennison
2022-06-07 19:53:42 +01:00
parent a8c0e47dd8
commit f54530b1b2
1 changed files with 10 additions and 0 deletions
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10
src/newgrf.cpp
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@@ -5707,6 +5707,7 @@ static bool IsFeatureUsableForDSE(GrfSpecFeature feature)
static const DeterministicSpriteGroupAdjust *GetVarAction2PreviousSingleLoadAdjust(const std::vector<DeterministicSpriteGroupAdjust> &adjusts, int start_index)
{
bool passed_store_perm = false;
for (int i = start_index; i >= 0; i--) {
const DeterministicSpriteGroupAdjust &prev = adjusts[i];
if (prev.variable == 0x7E) {
@@ -5714,6 +5715,14 @@ static const DeterministicSpriteGroupAdjust *GetVarAction2PreviousSingleLoadAdju
break;
}
if (prev.operation == DSGA_OP_RST) {
if (prev.variable == 0x7B) {
/* Can't use this previous load as it depends on the last value */
return nullptr;
}
if (prev.variable == 0x7C && passed_store_perm) {
/* If we passed a store perm then a load from permanent storage is not a valid previous load as we may have clobbered it */
return nullptr;
}
return &prev;
} else if (prev.operation == DSGA_OP_STO) {
if (prev.type == DSGA_TYPE_NONE && prev.variable == 0x1A && prev.shift_num == 0 && prev.and_mask < 0x100) {
@@ -5725,6 +5734,7 @@ static const DeterministicSpriteGroupAdjust *GetVarAction2PreviousSingleLoadAdju
}
} else if (prev.operation == DSGA_OP_STOP) {
/* Permanent storage store */
passed_store_perm = true;
continue;
} else {
break;