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/* Copyright 2013 Google Inc. All Rights Reserved.
Distributed under MIT license.
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/
/* Helper function for bit twiddling and macros for branch prediction. */
#ifndef WOFF2_PORT_H_
#define WOFF2_PORT_H_
#include <assert.h>
namespace woff2 {
typedef unsigned int uint32;
inline int Log2Floor(uint32 n) {
#if defined(__GNUC__)
return n == 0 ? -1 : 31 ^ __builtin_clz(n);
#else
if (n == 0)
return -1;
int log = 0;
uint32 value = n;
for (int i = 4; i >= 0; --i) {
int shift = (1 << i);
uint32 x = value >> shift;
if (x != 0) {
value = x;
log += shift;
}
}
assert(value == 1);
return log;
#endif
}
} // namespace woff2
/* Compatibility with non-clang compilers. */
#ifndef __has_builtin
#define __has_builtin(x) 0
#endif
#if (__GNUC__ > 2) || (__GNUC__ == 2 && __GNUC_MINOR__ > 95) || \
(defined(__llvm__) && __has_builtin(__builtin_expect))
#define PREDICT_FALSE(x) (__builtin_expect(x, 0))
#define PREDICT_TRUE(x) (__builtin_expect(!!(x), 1))
#else
#define PREDICT_FALSE(x) (x)
#define PREDICT_TRUE(x) (x)
#endif
#if (defined(__ARM_ARCH) && (__ARM_ARCH == 7)) || \
(defined(M_ARM) && (M_ARM == 7)) || \
defined(__aarch64__) || defined(__ARM64_ARCH_8__) || defined(__i386) || \
defined(_M_IX86) || defined(__x86_64__) || defined(_M_X64)
#if defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
#define WOFF_LITTLE_ENDIAN
#elif defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
#define WOFF_BIG_ENDIAN
#endif /* endianness */
#endif /* CPU whitelist */
#endif // WOFF2_PORT_H_
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