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Fix: [NewGRF] Make VA2 operator 11 (ror) behave well-defined when rotating by 0 bits.

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This commit is contained in:
frosch 2018-10-31 13:07:51 +01:00 committed by Niels Martin Hansen
parent b3dc90af58
commit 18ca3e8660
2 changed files with 3 additions and 17 deletions
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2
src/core/bitmath_func.hpp
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@ -302,6 +302,7 @@ static inline bool HasAtMostOneBit(T value)
template <typename T>
static inline T ROL(const T x, const uint8 n)
{
if (n == 0) return x;
return (T)(x << n | x >> (sizeof(x) * 8 - n));
}
@ -317,6 +318,7 @@ static inline T ROL(const T x, const uint8 n)
template <typename T>
static inline T ROR(const T x, const uint8 n)
{
if (n == 0) return x;
return (T)(x >> n | x << (sizeof(x) * 8 - n));
}

18
src/newgrf_spritegroup.cpp
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@ -144,22 +144,6 @@ static inline uint32 GetVariable(const ResolverObject &object, ScopeResolver *sc
return &this->default_scope;
}
/**
* Rotate val rot times to the right
* @param val the value to rotate
* @param rot the amount of times to rotate
* @return the rotated value
*/
static uint32 RotateRight(uint32 val, uint32 rot)
{
/* Do not rotate more than necessary */
rot %= 32;
assert(rot > 0);
return (val >> rot) | (val << (32 - rot));
}
/* Evaluate an adjustment for a variable of the given size.
* U is the unsigned type and S is the signed type to use. */
template <typename U, typename S>
@ -192,7 +176,7 @@ static U EvalAdjustT(const DeterministicSpriteGroupAdjust *adjust, ScopeResolver
case DSGA_OP_STO: _temp_store.StoreValue((U)value, (S)last_value); return last_value;
case DSGA_OP_RST: return value;
case DSGA_OP_STOP: scope->StorePSA((U)value, (S)last_value); return last_value;
case DSGA_OP_ROR: return RotateRight(last_value, value);
case DSGA_OP_ROR: return ROR<uint32>((U)last_value, (U)value & 0x1F); // mask 'value' to 5 bits, which should behave the same on all architectures.
case DSGA_OP_SCMP: return ((S)last_value == (S)value) ? 1 : ((S)last_value < (S)value ? 0 : 2);
case DSGA_OP_UCMP: return ((U)last_value == (U)value) ? 1 : ((U)last_value < (U)value ? 0 : 2);
case DSGA_OP_SHL: return (uint32)(U)last_value << ((U)value & 0x1F); // Same behaviour as in ParamSet, mask 'value' to 5 bits, which should behave the same on all architectures.