littlefs/lfs_util.h

/*
 * 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);
}

static inline uint32_t lfs_fromle32(uint32_t a) {
#if ( \
    (defined(  BYTE_ORDER  ) &&   BYTE_ORDER   ==   ORDER_LITTLE_ENDIAN  ) || \
    (defined(__BYTE_ORDER  ) && __BYTE_ORDER   == __ORDER_LITTLE_ENDIAN  ) || \
    (defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__))
    return a;
#elif ( \
    (defined(  BYTE_ORDER  ) &&   BYTE_ORDER   ==   ORDER_BIG_ENDIAN  ) || \
    (defined(__BYTE_ORDER  ) && __BYTE_ORDER   == __ORDER_BIG_ENDIAN  ) || \
    (defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
    return __builtin_bswap32(a);
#else
    return (((uint8_t*)&a)[0] <<  0) |
           (((uint8_t*)&a)[1] <<  8) |
           (((uint8_t*)&a)[2] << 16) |
           (((uint8_t*)&a)[3] << 24);
#endif
}

static inline uint32_t lfs_tole32(uint32_t a) {
    return lfs_fromle32(a);
}

// 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