mirror of
https://github.com/eledio-devices/thirdparty-littlefs.git
synced 2025-10-31 00:32:38 +01:00
4f08424b51
This helps significantly with supporting different compilers. Intrinsics for different compilers can be added as they are found. Note that for ARMCC, __builtin_ctz is not used. This was the result of a strange issue where ARMCC only emits __builtin_ctz when passed the --gnu flag, but __builtin_clz and __builtin_popcount are always emitted. This isn't a big problem since the ARM instruction set doesn't have a ctz instruction, and the npw2 based implementation is one of the most efficient. Also note that for littefs's purposes, we consider ctz(0) to be undefined. This lets us save a branch in the software lfs_ctz implementation.
85 lines
2.3 KiB
C
85 lines
2.3 KiB
C
/*
|
|
* lfs utility functions
|
|
*
|
|
* Copyright (c) 2017 ARM Limited
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
#ifndef LFS_UTIL_H
|
|
#define LFS_UTIL_H
|
|
|
|
#include <stdlib.h>
|
|
#include <stdint.h>
|
|
#include <stdio.h>
|
|
|
|
|
|
// Builtin functions, these may be replaced by more
|
|
// efficient implementations in the system
|
|
static inline uint32_t lfs_max(uint32_t a, uint32_t b) {
|
|
return (a > b) ? a : b;
|
|
}
|
|
|
|
static inline uint32_t lfs_min(uint32_t a, uint32_t b) {
|
|
return (a < b) ? a : b;
|
|
}
|
|
|
|
static inline uint32_t lfs_npw2(uint32_t a) {
|
|
#if defined(__GNUC__) || defined(__CC_ARM)
|
|
return 32 - __builtin_clz(a-1);
|
|
#else
|
|
uint32_t r = 0;
|
|
uint32_t s;
|
|
a -= 1;
|
|
s = (a > 0xffff) << 4; a >>= s; r |= s;
|
|
s = (a > 0xff ) << 3; a >>= s; r |= s;
|
|
s = (a > 0xf ) << 2; a >>= s; r |= s;
|
|
s = (a > 0x3 ) << 1; a >>= s; r |= s;
|
|
return (r | (a >> 1)) + 1;
|
|
#endif
|
|
}
|
|
|
|
static inline uint32_t lfs_ctz(uint32_t a) {
|
|
#if defined(__GNUC__)
|
|
return __builtin_ctz(a);
|
|
#else
|
|
return lfs_npw2((a & -a) + 1) - 1;
|
|
#endif
|
|
}
|
|
|
|
static inline uint32_t lfs_popc(uint32_t a) {
|
|
#if defined(__GNUC__) || defined(__CC_ARM)
|
|
return __builtin_popcount(a);
|
|
#else
|
|
a = a - ((a >> 1) & 0x55555555);
|
|
a = (a & 0x33333333) + ((a >> 2) & 0x33333333);
|
|
return (((a + (a >> 4)) & 0xf0f0f0f) * 0x1010101) >> 24;
|
|
#endif
|
|
}
|
|
|
|
static inline int lfs_scmp(uint32_t a, uint32_t b) {
|
|
return (int)(unsigned)(a - b);
|
|
}
|
|
|
|
// CRC-32 with polynomial = 0x04c11db7
|
|
void lfs_crc(uint32_t *crc, const void *buffer, size_t size);
|
|
|
|
|
|
// Logging functions, these may be replaced by system-specific
|
|
// logging functions
|
|
#define LFS_DEBUG(fmt, ...) printf("lfs debug: " fmt "\n", __VA_ARGS__)
|
|
#define LFS_WARN(fmt, ...) printf("lfs warn: " fmt "\n", __VA_ARGS__)
|
|
#define LFS_ERROR(fmt, ...) printf("lfs error: " fmt "\n", __VA_ARGS__)
|
|
|
|
|
|
#endif
|