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littlefs/lfs_util.h
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Christopher Haster 415e6325d1 Moved revision count noise behind ifdef LFS_NOISY 
littlefs is intentionally designed to not rely on noise, even with cksum
collisions (hello, perturb bit!). So it makes sense for this to be an
optional feature, even if it's a small one.

Disabling revision count noise by default also helps with testing. The
whole point of revision count noise is to make cksum collisions less
likely, which is a bit counterproductive when that's something we want
to test!

This doesn't really change the revision count encoding:

  vvvvrrrr rrrrrrnn nnnnnnnn nnnnnnnn
  '-.''----.----''---------.--------'
    '------|---------------|---------- 4-bit relocation revision
           '---------------|---------- recycle-bits recycle counter
                           '---------- pseudorandom noise (optional)

I considered moving the recycle-bits down when we're not adding noise,
but the extra logic just isn't worth making the revision count a bit
more human-readable.

---

This saves a small bit of code in the default build, at the cost of some
code for the runtime checks in the LFS_NOISY build. Though I'm hoping
future config work will let users opt-out of these runtime checks:

                    code          stack          ctx
  before:          38548           2624          640
  default after:   38508 (-0.1%)   2624 (+0.0%)  640 (+0.0%)
  LFS_NOISY after: 38568 (+0.1%)   2624 (+0.0%)  640 (+0.0%)

Honestly the thing I'm more worried about is using one of our precious
mount flags for this... There's not that many bits left!
2025-02-08 14:53:47 -06:00

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/*
* lfs utility functions
*
* Copyright (c) 2022, The littlefs authors.
* Copyright (c) 2017, Arm Limited. All rights reserved.
* SPDX-License-Identifier: BSD-3-Clause
*/
#ifndef LFS_UTIL_H
#define LFS_UTIL_H
// Users can override lfs_util.h with their own configuration by defining
// LFS_CONFIG as a header file to include (-DLFS_CONFIG=lfs_config.h).
//
// If LFS_CONFIG is used, none of the default utils will be emitted and must be
// provided by the config file. To start, I would suggest copying lfs_util.h
// and modifying as needed.
#ifdef LFS_CONFIG
#define LFS_STRINGIZE(x) LFS_STRINGIZE2(x)
#define LFS_STRINGIZE2(x) #x
#include LFS_STRINGIZE(LFS_CONFIG)
#else
// Some convenient macro aliases
// TODO move these to something like lfs_cfg.h?
// LFS_BIGGEST enables all opt-in features
#ifdef LFS_BIGGEST
#ifndef LFS_NOISY
#define LFS_NOISY
#endif
#ifndef LFS_CKPROGS
#define LFS_CKPROGS
#endif
#ifndef LFS_CKFETCHES
#define LFS_CKFETCHES
#endif
#ifndef LFS_CKPARITY
#define LFS_CKPARITY
#endif
#ifndef LFS_CKDATACKSUMS
#define LFS_CKDATACKSUMS
#endif
#ifndef LFS_GC
#define LFS_GC
#endif
#endif
// LFS_NO_LOG disables all logging macros
#ifdef LFS_NO_LOG
#ifndef LFS_NO_DEBUG
#define LFS_NO_DEBUG
#endif
#ifndef LFS_NO_INFO
#define LFS_NO_INFO
#endif
#ifndef LFS_NO_WARN
#define LFS_NO_WARN
#endif
#ifndef LFS_NO_ERROR
#define LFS_NO_ERROR
#endif
#endif
// System includes
#include <stdint.h>
#include <stdbool.h>
#include <sys/types.h>
#include <inttypes.h>
#ifndef LFS_NO_STRINGH
#include <string.h>
#endif
#ifndef LFS_NO_MALLOC
#include <stdlib.h>
#endif
#ifndef LFS_NO_ASSERT
#include <assert.h>
#endif
#if !defined(LFS_NO_DEBUG) || \
!defined(LFS_NO_INFO) || \
!defined(LFS_NO_WARN) || \
!defined(LFS_NO_ERROR) || \
defined(LFS_YES_TRACE)
#include <stdio.h>
#endif
#ifdef __cplusplus
extern "C"
{
#endif
// Macros, may be replaced by system specific wrappers. Arguments to these
// macros must not have side-effects as the macros can be removed for a smaller
// code footprint
// Logging functions
#ifndef LFS_TRACE
#ifdef LFS_YES_TRACE
#define LFS_TRACE_(fmt, ...) \
printf("%s:%d:trace: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__)
#define LFS_TRACE(...) LFS_TRACE_(__VA_ARGS__, "")
#else
#define LFS_TRACE(...)
#endif
#endif
#ifndef LFS_DEBUG
#ifndef LFS_NO_DEBUG
#define LFS_DEBUG_(fmt, ...) \
printf("%s:%d:debug: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__)
#define LFS_DEBUG(...) LFS_DEBUG_(__VA_ARGS__, "")
#else
#define LFS_DEBUG(...)
#endif
#endif
#ifndef LFS_INFO
#ifndef LFS_NO_INFO
#define LFS_INFO_(fmt, ...) \
printf("%s:%d:info: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__)
#define LFS_INFO(...) LFS_INFO_(__VA_ARGS__, "")
#else
#define LFS_INFO(...)
#endif
#endif
#ifndef LFS_WARN
#ifndef LFS_NO_WARN
#define LFS_WARN_(fmt, ...) \
printf("%s:%d:warn: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__)
#define LFS_WARN(...) LFS_WARN_(__VA_ARGS__, "")
#else
#define LFS_WARN(...)
#endif
#endif
#ifndef LFS_ERROR
#ifndef LFS_NO_ERROR
#define LFS_ERROR_(fmt, ...) \
printf("%s:%d:error: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__)
#define LFS_ERROR(...) LFS_ERROR_(__VA_ARGS__, "")
#else
#define LFS_ERROR(...)
#endif
#endif
// Runtime assertions
#ifndef LFS_ASSERT
#ifndef LFS_NO_ASSERT
#define LFS_ASSERT(test) assert(test)
#else
#define LFS_ASSERT(test)
#endif
#endif
#ifndef LFS_UNREACHABLE
#ifndef LFS_NO_ASSERT
#define LFS_UNREACHABLE() LFS_ASSERT(false)
#elif !defined(LFS_NO_BUILTINS)
#define LFS_UNREACHABLE() __builtin_unreachable()
#else
#define LFS_UNREACHABLE()
#endif
#endif
// We need to know the endianness of the system for some struct packing
#if (defined(BYTE_ORDER) \
&& defined(ORDER_LITTLE_ENDIAN) \
&& BYTE_ORDER == ORDER_LITTLE_ENDIAN) \
|| (defined(__BYTE_ORDER) \
&& defined(__ORDER_LITTLE_ENDIAN) \
&& __BYTE_ORDER == __ORDER_LITTLE_ENDIAN) \
|| (defined(__BYTE_ORDER__) \
&& defined(__ORDER_LITTLE_ENDIAN__) \
&& __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
#define LFS_LITTLE_ENDIAN
#elif (defined(BYTE_ORDER) \
&& defined(ORDER_BIG_ENDIAN) \
&& BYTE_ORDER == ORDER_BIG_ENDIAN) \
|| (defined(__BYTE_ORDER) \
&& defined(__ORDER_BIG_ENDIAN) \
&& __BYTE_ORDER == __ORDER_BIG_ENDIAN) \
|| (defined(__BYTE_ORDER__) \
&& defined(__ORDER_BIG_ENDIAN__) \
&& __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
#define LFS_BIG_ENDIAN
#else
#error "lfs: Unknown endianness?"
#endif
// Some ifdef conveniences
#ifdef LFS_NOISY
#define LFS_IFDEF_NOISY(a, b) (a)
#else
#define LFS_IFDEF_NOISY(a, b) (b)
#endif
#ifdef LFS_CKPROGS
#define LFS_IFDEF_CKPROGS(a, b) (a)
#else
#define LFS_IFDEF_CKPROGS(a, b) (b)
#endif
#ifdef LFS_CKFETCHES
#define LFS_IFDEF_CKFETCHES(a, b) (a)
#else
#define LFS_IFDEF_CKFETCHES(a, b) (b)
#endif
#ifdef LFS_CKPARITY
#define LFS_IFDEF_CKPARITY(a, b) (a)
#else
#define LFS_IFDEF_CKPARITY(a, b) (b)
#endif
#ifdef LFS_CKDATACKSUMS
#define LFS_IFDEF_CKDATACKSUMS(a, b) (a)
#else
#define LFS_IFDEF_CKDATACKSUMS(a, b) (b)
#endif
#ifdef LFS_GC
#define LFS_IFDEF_GC(a, b) (a)
#else
#define LFS_IFDEF_GC(a, b) (b)
#endif
// Builtin functions, these may be replaced by more efficient
// toolchain-specific implementations. LFS_NO_BUILTINS falls back to a more
// expensive basic C implementation for debugging purposes
// Compile time min/max
#define LFS_MIN(a, b) ((a < b) ? a : b)
#define LFS_MAX(a, b) ((a > b) ? a : b)
// Min/max functions for unsigned 32-bit numbers
static inline uint32_t lfs_min(uint32_t a, uint32_t b) {
return (a < b) ? a : b;
}
static inline uint32_t lfs_max(uint32_t a, uint32_t b) {
return (a > b) ? a : b;
}
static inline int32_t lfs_smin(int32_t a, int32_t b) {
return (a < b) ? a : b;
}
static inline int32_t lfs_smax(int32_t a, int32_t b) {
return (a > b) ? a : b;
}
// Absolute value of signed numbers
static inline int32_t lfs_abs(int32_t a) {
return (a < 0) ? -a : a;
}
// Swap two variables
#define LFS_SWAP(_t, _a, _b) \
do { \
_t *a = _a; \
_t *b = _b; \
_t t = *a; \
*a = *b; \
*b = t; \
} while (0)
// Align to nearest multiple of a size
static inline uint32_t lfs_aligndown(uint32_t a, uint32_t alignment) {
return a - (a % alignment);
}
static inline uint32_t lfs_alignup(uint32_t a, uint32_t alignment) {
return lfs_aligndown(a + alignment-1, alignment);
}
// Find the smallest power of 2 greater than or equal to a
static inline uint32_t lfs_npw2(uint32_t a) {
// __builtin_clz of zero is undefined, so treat both 0 and 1 specially
if (a <= 1) {
return a;
}
#if !defined(LFS_NO_BUILTINS) && (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
}
// TODO we should eventually adopt this as the new name for npw2
// Find the ceiling of log base 2 of the given number
static inline uint32_t lfs_nlog2(uint32_t a) {
return lfs_npw2(a);
}
// Count the number of trailing binary zeros in a
// lfs_ctz(0) may be undefined
static inline uint32_t lfs_ctz(uint32_t a) {
#if !defined(LFS_NO_BUILTINS) && defined(__GNUC__)
return __builtin_ctz(a);
#else
return lfs_npw2((a & -a) + 1) - 1;
#endif
}
// Count the number of binary ones in a
static inline uint32_t lfs_popc(uint32_t a) {
#if !defined(LFS_NO_BUILTINS) && (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
}
// Returns true if there is an odd number of binary ones in a
static inline bool lfs_parity(uint32_t a) {
#if !defined(LFS_NO_BUILTINS) && (defined(__GNUC__) || defined(__CC_ARM))
return __builtin_parity(a);
#else
return lfs_popc(a) & 1;
#endif
}
// Find the sequence comparison of a and b, this is the distance
// between a and b ignoring overflow
static inline int lfs_scmp(uint32_t a, uint32_t b) {
return (int)(unsigned)(a - b);
}
// Perform polynomial/carry-less multiplication
//
// This is a multiply where all adds are replaced with xors. If we view
// a and b as binary polynomials, xor is polynomial addition and pmul is
// polynomial multiplication.
static inline uint64_t lfs_pmul(uint32_t a, uint32_t b) {
uint64_t r = 0;
uint64_t a_ = a;
while (b) {
if (b & 1) {
r ^= a_;
}
a_ <<= 1;
b >>= 1;
}
return r;
}
// Convert between 32-bit little-endian and native order
static inline uint32_t lfs_fromle32(uint32_t a) {
#if !defined(LFS_NO_BUILTINS) && defined(LFS_LITTLE_ENDIAN)
return a;
#elif !defined(LFS_NO_BUILTINS)
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);
}
// Convert between 32-bit big-endian and native order
static inline uint32_t lfs_frombe32(uint32_t a) {
#if !defined(LFS_NO_BUILTINS) && defined(LFS_LITTLE_ENDIAN)
return __builtin_bswap32(a);
#elif !defined(LFS_NO_BUILTINS)
return a;
#else
return (((uint8_t*)&a)[0] << 24) |
(((uint8_t*)&a)[1] << 16) |
(((uint8_t*)&a)[2] << 8) |
(((uint8_t*)&a)[3] << 0);
#endif
}
static inline uint32_t lfs_tobe32(uint32_t a) {
return lfs_frombe32(a);
}
// Convert to/from 16-bit little-endian
static inline void lfs_tole16_(uint16_t word, void *buffer) {
((uint8_t*)buffer)[0] = word >> 0;
((uint8_t*)buffer)[1] = word >> 8;
}
static inline uint16_t lfs_fromle16_(const void *buffer) {
return (((uint8_t*)buffer)[0] << 0)
| (((uint8_t*)buffer)[1] << 8);
}
// Convert to/from 32-bit little-endian
static inline void lfs_tole32_(uint32_t word, void *buffer) {
((uint8_t*)buffer)[0] = word >> 0;
((uint8_t*)buffer)[1] = word >> 8;
((uint8_t*)buffer)[2] = word >> 16;
((uint8_t*)buffer)[3] = word >> 24;
}
static inline uint32_t lfs_fromle32_(const void *buffer) {
return (((uint8_t*)buffer)[0] << 0)
| (((uint8_t*)buffer)[1] << 8)
| (((uint8_t*)buffer)[2] << 16)
| (((uint8_t*)buffer)[3] << 24);
}
// Convert to/from leb128 encoding
// TODO should we really be using ssize_t here and not lfs_ssize_t?
ssize_t lfs_toleb128(uint32_t word, void *buffer, size_t size);
ssize_t lfs_fromleb128(uint32_t *word, const void *buffer, size_t size);
// Compare n bytes of memory
#if !defined(LFS_NO_STRINGH)
#define lfs_memcmp memcmp
#elif !defined(LFS_NO_BUILTINS)
#define lfs_memcmp __builtin_memcmp
#else
static inline int lfs_memcmp(const void *a, const void *b, size_t size) {
const uint8_t *a_ = a;
const uint8_t *b_ = b;
for (size_t i = 0; i < size; i++) {
if (a_[i] != b_[i]) {
return (int)a_[i] - (int)b_[i];
}
}
return 0;
}
#endif
// Copy n bytes from src to dst, src and dst must not overlap
#if !defined(LFS_NO_STRINGH)
#define lfs_memcpy memcpy
#elif !defined(LFS_NO_BUILTINS)
#define lfs_memcpy __builtin_memcpy
#else
static inline void *lfs_memcpy(
void *restrict dst, const void *restrict src, size_t size) {
uint8_t *dst_ = dst;
const uint8_t *src_ = src;
for (size_t i = 0; i < size; i++) {
dst_[i] = src_[i];
}
return dst_;
}
#endif
// Copy n bytes from src to dst, src and dst may overlap
#if !defined(LFS_NO_STRINGH)
#define lfs_memmove memmove
#elif !defined(LFS_NO_BUILTINS)
#define lfs_memmove __builtin_memmove
#else
static inline void *lfs_memmove(void *dst, const void *src, size_t size) {
uint8_t *dst_ = dst;
const uint8_t *src_ = src;
if (dst_ < src_) {
for (size_t i = 0; i < size; i++) {
dst_[i] = src_[i];
}
} else if (dst_ > src_) {
for (size_t i = 0; i < size; i++) {
dst_[(size-1)-i] = src_[(size-1)-i];
}
}
return dst_;
}
#endif
// Set n bytes to c
#if !defined(LFS_NO_STRINGH)
#define lfs_memset memset
#elif !defined(LFS_NO_BUILTINS)
#define lfs_memset __builtin_memset
#else
static inline void *lfs_memset(void *dst, int c, size_t size) {
uint8_t *dst_ = dst;
for (size_t i = 0; i < size; i++) {
dst_[i] = c;
}
return dst_;
}
#endif
// Find the first occurrence of c or NULL
#if !defined(LFS_NO_STRINGH)
#define lfs_memchr memchr
#else
static inline void *lfs_memchr(const void *a, int c, size_t size) {
const uint8_t *a_ = a;
for (size_t i = 0; i < size; i++) {
if (a_[i] == c) {
return (void*)&a_[i];
}
}
return NULL;
}
#endif
// Find the first occurrence of anything not c or NULL
static inline void *lfs_memcchr(const void *a, int c, size_t size) {
const uint8_t *a_ = a;
for (size_t i = 0; i < size; i++) {
if (a_[i] != c) {
return (void*)&a_[i];
}
}
return NULL;
}
// Find the minimum length that includes all non-zero bytes
static inline size_t lfs_memlen(const void *a, size_t size) {
const uint8_t *a_ = a;
while (size > 0 && a_[size-1] == 0) {
size -= 1;
}
return size;
}
// Xor n bytes from b into a
static inline void *lfs_memxor(
void *restrict a, const void *restrict b, size_t size) {
uint8_t *a_ = a;
const uint8_t *b_ = b;
for (size_t i = 0; i < size; i++) {
a_[i] ^= b_[i];
}
return a_;
}
// Find the length of a null-terminated string
#if !defined(LFS_NO_STRINGH)
#define lfs_strlen strlen
#else
static inline size_t lfs_strlen(const char *a) {
const char *a_ = a;
while (*a_) {
a_++;
}
return a_ - a;
}
#endif
// Compare two null-terminated strings
#if !defined(LFS_NO_STRINGH)
#define lfs_strcmp strcmp
#else
static inline int lfs_strcmp(const char *a, const char *b) {
while (*a && *a == *b) {
a++;
b++;
}
return (int)*a - (int)*b;
}
#endif
// Copy a null-terminated string from src to dst
#if !defined(LFS_NO_STRINGH)
#define lfs_strcpy strcpy
#else
static inline char *lfs_strcpy(
char *restrict dst, const char *restrict src) {
char *dst_ = dst;
while (*src) {
*dst_ = *src;
dst_++;
src++;
}
*dst_ = '\0';
return dst;
}
#endif
// Find first occurrence of c or NULL
#ifndef LFS_NO_STRINGH
#define lfs_strchr strchr
#else
static inline char *lfs_strchr(const char *a, int c) {
while (*a) {
if (*a == c) {
return (char*)a;
}
a++;
}
return NULL;
}
#endif
// Find first occurrence of anything not c or NULL
static inline char *lfs_strcchr(const char *a, int c) {
while (*a) {
if (*a != c) {
return (char*)a;
}
a++;
}
return NULL;
}
// Find length of a that does not contain any char in cs
#ifndef LFS_NO_STRINGH
#define lfs_strspn strspn
#else
static inline size_t lfs_strspn(const char *a, const char *cs) {
const char *a_ = a;
while (*a_) {
const char *cs_ = cs;
while (*cs_) {
if (*a_ != *cs_) {
return a_ - a;
}
cs_++;
}
a_++;
}
return a_ - a;
}
#endif
// Find length of a that only contains chars in cs
#ifndef LFS_NO_STRINGH
#define lfs_strcspn strcspn
#else
static inline size_t lfs_strcspn(const char *a, const char *cs) {
const char *a_ = a;
while (*a_) {
const char *cs_ = cs;
while (*cs_) {
if (*a_ == *cs_) {
return a_ - a;
}
cs_++;
}
a_++;
}
return a_ - a;
}
#endif
//// Calculate CRC-32 with polynomial = 0x04c11db7
//uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size);
// Odd-parity and even-parity zeros in our crc32c ring
#define LFS_CRC32C_ODDZERO 0xfca42daf
#define LFS_CRC32C_EVENZERO 0x00000000
// Calculate crc32c incrementally
//
// polynomial = 0x11edc6f41
// init = 0xffffffff
// fini = 0xffffffff
//
uint32_t lfs_crc32c(uint32_t crc, const void *buffer, size_t size);
// Multiply two crc32cs in the crc32c ring
uint32_t lfs_crc32c_mul(uint32_t a, uint32_t b);
// Find the cube of a crc32c in the crc32c ring
static inline uint32_t lfs_crc32c_cube(uint32_t a) {
return lfs_crc32c_mul(lfs_crc32c_mul(a, a), a);
}
// Allocate memory, only used if buffers are not provided to littlefs
// Note, memory must be 64-bit aligned
#ifndef LFS_NO_MALLOC
#define lfs_malloc malloc
#else
static inline void *lfs_malloc(size_t size) {
(void)size;
return NULL;
}
#endif
// Deallocate memory, only used if buffers are not provided to littlefs
#ifndef LFS_NO_MALLOC
#define lfs_free free
#else
static inline void lfs_free(void *p) {
(void)p;
}
#endif
#ifdef __cplusplus
} /* extern "C" */
#endif
#endif
#endif
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