sonyoss-vita-webkit/Source/WTF/wtf/SaturatedArithmetic.h

/*
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#ifndef SaturatedArithmetic_h
#define SaturatedArithmetic_h

#include <limits>
#include <stdint.h>
#include <stdlib.h>

inline int32_t saturatedAddition(int32_t a, int32_t b)
{
    uint32_t ua = a;
    uint32_t ub = b;
    uint32_t result = ua + ub;

    // Can only overflow if the signed bit of the two values match. If the signed
    // bit of the result and one of the values differ it did overflow.
    if (!((ua ^ ub) >> 31) & (result ^ ua) >> 31)
        result = std::numeric_limits<int>::max() + (ua >> 31);

    return result;
}

inline int32_t saturatedSubtraction(int32_t a, int32_t b)
{
    uint32_t ua = a;
    uint32_t ub = b;
    uint32_t result = ua - ub;

    // Can only overflow if the signed bit of the two values do not match. If the
    // signed bit of the result and the first value differ it did overflow.
    if ((ua ^ ub) >> 31 & (result ^ ua) >> 31)
        result = std::numeric_limits<int>::max() + (ua >> 31);

    return result;
}

#endif // SaturatedArithmetic_h