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/*
* C language compatibility macros for varying compiler support.
*/
#ifndef CCOMPAT_H
#define CCOMPAT_H
// Marking GNU extensions to avoid warnings.
#if defined(__GNUC__)
#define GNU_EXTENSION __extension__
#else
#define GNU_EXTENSION
#endif
// Variable length arrays.
// VLA(type, name, size) allocates a variable length array with automatic
// storage duration. VLA_SIZE(name) evaluates to the runtime size of that array
// in bytes.
//
// If C99 VLAs are not available, an emulation using alloca (stack allocation
// "function") is used. Note the semantic difference: alloca'd memory does not
// get freed at the end of the declaration's scope. Do not use VLA() in loops or
// you may run out of stack space.
#if !defined(_MSC_VER) && __STDC_VERSION__ >= 199901L
// C99 VLAs.
#define VLA(type, name, size) type name[size]
#define SIZEOF_VLA sizeof
#else
// Emulation using alloca.
#ifdef _WIN32
#include <malloc.h>
#else
#include <alloca.h>
#endif
#define VLA(type, name, size) \
const size_t name##_size = (size) * sizeof(type); \
type *const name = (type *)alloca(name##_size)
#define SIZEOF_VLA(name) name##_size
#endif
#endif /* CCOMPAT_H */
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