ckdint.h

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#ifndef SOLIDC_CKDINT_H
#define SOLIDC_CKDINT_H
 
#include <stdbool.h>
#include <stddef.h>
 
/*
 * Detect if the compiler supports GCC/Clang style built-in overflow checks.
 * GCC 5+ and Clang 3.8+ support these.
 */
#if defined(__has_builtin)
#if __has_builtin(__builtin_add_overflow)
#define SOLIDC_USE_BUILTINS
#endif
#elif defined(__GNUC__) && (__GNUC__ >= 5)
#define SOLIDC_USE_BUILTINS
#endif
 
#ifdef SOLIDC_USE_BUILTINS
 
/*
 * Generic Macros: These work for int, long, size_t, etc.
 * Returns true (1) if overflow occurred, false (0) otherwise.
 */
#define ckd_add(r, a, b) __builtin_add_overflow((a), (b), (r))
#define ckd_sub(r, a, b) __builtin_sub_overflow((a), (b), (r))
#define ckd_mul(r, a, b) __builtin_mul_overflow((a), (b), (r))
 
#else
 
/*
 * Fallback (MSVC / ANSI C):
 * Portable implementations for size_t (unsigned arithmetic).
 */
 
static inline bool ckd_add(size_t* r, size_t a, size_t b) {
    *r = a + b;
    return *r < a;
}
 
static inline bool ckd_sub(size_t* r, size_t a, size_t b) {
    *r = a - b;
    return *r > a;
}
 
static inline bool ckd_mul(size_t* r, size_t a, size_t b) {
    if (a == 0 || b == 0) {
        *r = 0;
        return false;
    }
    *r = a * b;
    return (*r / a) != b;
}
 
#endif /* SOLIDC_USE_BUILTINS */
 
#undef SOLIDC_USE_BUILTINS
 
#endif /* SOLIDC_CKDINT_H */