121 lines
3.2 KiB
C
121 lines
3.2 KiB
C
/*
|
|
* Copyright (c) 2016, Alliance for Open Media. All rights reserved.
|
|
*
|
|
* This source code is subject to the terms of the BSD 2 Clause License and
|
|
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
|
|
* was not distributed with this source code in the LICENSE file, you can
|
|
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
|
|
* Media Patent License 1.0 was not distributed with this source code in the
|
|
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
|
|
*/
|
|
|
|
#ifndef AOM_AOM_PORTS_BITOPS_H_
|
|
#define AOM_AOM_PORTS_BITOPS_H_
|
|
|
|
#include <assert.h>
|
|
#include <stdint.h>
|
|
|
|
#include "config/aom_config.h"
|
|
|
|
#ifdef _MSC_VER
|
|
#if defined(_M_X64) || defined(_M_IX86) || defined(_M_ARM64) || defined(_M_ARM)
|
|
#include <intrin.h>
|
|
#define USE_MSC_INTRINSICS
|
|
#endif
|
|
#endif
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
// get_msb:
|
|
// Returns (int)floor(log2(n)). n must be > 0.
|
|
// These versions of get_msb() are only valid when n != 0 because all
|
|
// of the optimized versions are undefined when n == 0:
|
|
|
|
// GCC compiler: https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
|
|
// MSVC: https://learn.microsoft.com/en-us/cpp/intrinsics/compiler-intrinsics
|
|
|
|
// use GNU builtins where available.
|
|
#if defined(__GNUC__) && \
|
|
((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
|
|
static inline int get_msb(unsigned int n) {
|
|
assert(n != 0);
|
|
return 31 ^ __builtin_clz(n);
|
|
}
|
|
#elif defined(USE_MSC_INTRINSICS)
|
|
#pragma intrinsic(_BitScanReverse)
|
|
|
|
static inline int get_msb(unsigned int n) {
|
|
unsigned long first_set_bit;
|
|
assert(n != 0);
|
|
_BitScanReverse(&first_set_bit, n);
|
|
return first_set_bit;
|
|
}
|
|
#else
|
|
static inline int get_msb(unsigned int n) {
|
|
int log = 0;
|
|
unsigned int value = n;
|
|
|
|
assert(n != 0);
|
|
|
|
for (int shift = 16; shift != 0; shift >>= 1) {
|
|
const unsigned int x = value >> shift;
|
|
if (x != 0) {
|
|
value = x;
|
|
log += shift;
|
|
}
|
|
}
|
|
return log;
|
|
}
|
|
#endif
|
|
|
|
#if defined(__GNUC__) && \
|
|
((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
|
|
static inline int aom_clzll(uint64_t n) { return __builtin_clzll(n); }
|
|
#elif defined(USE_MSC_INTRINSICS)
|
|
#if defined(_M_X64) || defined(_M_ARM64)
|
|
#pragma intrinsic(_BitScanReverse64)
|
|
#endif
|
|
|
|
static inline int aom_clzll(uint64_t n) {
|
|
assert(n != 0);
|
|
unsigned long first_set_bit; // NOLINT(runtime/int)
|
|
#if defined(_M_X64) || defined(_M_ARM64)
|
|
const unsigned char bit_set =
|
|
_BitScanReverse64(&first_set_bit, (unsigned __int64)n);
|
|
#else // !(defined(_M_X64) || defined(_M_ARM64))
|
|
const unsigned long n_hi = (unsigned long)(n >> 32); // NOLINT(runtime/int)
|
|
if (n_hi != 0) {
|
|
const unsigned char bit_set = _BitScanReverse(&first_set_bit, n_hi);
|
|
assert(bit_set != 0);
|
|
(void)bit_set;
|
|
return 31 ^ (int)first_set_bit;
|
|
}
|
|
const unsigned char bit_set =
|
|
_BitScanReverse(&first_set_bit, (unsigned long)n); // NOLINT(runtime/int)
|
|
#endif
|
|
assert(bit_set != 0);
|
|
(void)bit_set;
|
|
return 63 ^ (int)first_set_bit;
|
|
}
|
|
#undef USE_MSC_INTRINSICS
|
|
#else
|
|
static inline int aom_clzll(uint64_t n) {
|
|
assert(n != 0);
|
|
|
|
int res = 0;
|
|
uint64_t high_bit = 1ULL << 63;
|
|
while (!(n & high_bit)) {
|
|
res++;
|
|
n <<= 1;
|
|
}
|
|
return res;
|
|
}
|
|
#endif
|
|
|
|
#ifdef __cplusplus
|
|
} // extern "C"
|
|
#endif
|
|
|
|
#endif // AOM_AOM_PORTS_BITOPS_H_
|