stddef.h

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#ifndef __STDDEF_H__
#define __STDDEF_H__
 
#ifdef __cplusplus
extern "C" {
#endif
 
#if defined(__cplusplus)
#define NULL (0)
#else
#define NULL ((void *) 0)
#endif
 
#if (defined(__GNUC__) && (__GNUC__ >= 4))
#define offsetof(type, member) __builtin_offsetof(type, member)
#else
#define offsetof(type, field) ((size_t) (&((type *) 0)->field))
#endif
#define container_of(ptr, type, member)                      \
    ({                                                       \
        const typeof(((type *) 0)->member) *__mptr = (ptr);  \
        (type *) ((char *) __mptr - offsetof(type, member)); \
    })
 
#if (defined(__GNUC__) && (__GNUC__ >= 3))
#define likely(expr) (__builtin_expect(!!(expr), 1))
#define unlikely(expr) (__builtin_expect(!!(expr), 0))
#else
#define likely(expr) (!!(expr))
#define unlikely(expr) (!!(expr))
#endif
 
#define min(a, b) (((a) < (b)) ? (a) : (b))
#define max(a, b) (((a) > (b)) ? (a) : (b))
 
#define clamp(v, a, b) min(max(a, v), b)
 
#define ifloor(x) ((x) > 0 ? (int) (x) : (int) ((x) -0.9999999999))
#define iround(x) ((x) > 0 ? (int) ((x) + 0.5) : (int) ((x) -0.5))
#define iceil(x) ((x) > 0 ? (int) ((x) + 0.9999999999) : (int) (x))
#define idiv255(x) ((((int) (x) + 1) * 257) >> 16)
 
#ifdef __cplusplus
}
#endif
 
#endif /* __STDDEF_H__ */