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littlefs/lfs_util.h
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Christopher Haster b563050fc8 Dropped LFS_ASSERT as a compiler hint 
I realized the reason asserting on opened/closed file handles added so
much extra code was because our LFS_ASSERT macro doesn't properly
eliminate side-effects.

Consider this assert:

  LFS_ASSERT(lfsr_opened_isopen(lfs, &dir->o));

Expanded:

  ((lfsr_opened_isopen(lfs, &dir->o))
      ? (void)0
      : __builtin_unreachable());

Even though the compiler knows lfsr_opened_isopen must return true
here, it doesn't know what possible side-effects calling
lfsr_opened_isopen may have, and can't eliminate the function call.

This is quite a bit more obvious if you did something like:

  LFS_ASSERT(lfsr_file_sync(&lfs, &file) == 0);

But since lfsr_opened_isopen is a static inline function, it gets a
little bit less clear. Even worse, whether or not the call is eliminated
probably depends if it's actually inlined and other compiler
optimization noise.

---

This commit effectively reverts LFS_ASSERT as a compiler hint, making
LFS_ASSERT an empty string if LFS_NO_ASSERT is defined.

This may not be the optimal solution, but it at least keeps the
programmer's intuition that anything in LFS_ASSERT has zero impact when
asserts are disabled. It would be nice if there was some way to tell the
compiler that an expression should have no side-effects, but as far as
I'm aware this is not currently possible.

Measurements show that just disabling asserts wins in both code and
stack over trying to leverage asserts-as-hints:

                         code          stack
  hint-assert (before): 33904           2584
  no-assert (after):    33626 (-0.8%)   2552 (-1.2%)

At least both of these win over leaving asserts enabled, so
asserts-as-hints does eliminate _most_ code (measured here
with a simple assert-loop, since I assume that would have the smallest
code footprint):

                         code          stack
  loop-assert:          36874           2616
  hint-assert (before): 33904 (-8.1%)   2584 (-1.2%)
  no-assert (after):    33626 (-8.8%)   2552 (-2.4%)

Unfortunately asserts-as-hints was doing quite a bit of heavy lifting
at preventing overzealous GCC warnings. It took quite a few tweaks to
get GCC to shut up, and I'm still not entirely sure the best way to tell
GCC that some functions only return negative values. Currently I just
limit certain error checks to only check for negative values, which is
not great, but at least gets the code compiling again...
2024-06-20 12:56:30 -05:00

641 lines
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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
// 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_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_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
// 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 uint32_t lfs_min32(uint32_t a, uint32_t b) {
return (a < b) ? a : b;
}
static inline uint32_t lfs_max32(uint32_t a, uint32_t b) {
return (a > b) ? a : b;
}
static inline int32_t lfs_smin32(int32_t a, int32_t b) {
return (a < b) ? a : b;
}
static inline int32_t lfs_smax32(int32_t a, int32_t b) {
return (a > b) ? a : b;
}
// TODO other 16-bit ops?
static inline uint16_t lfs_min16(uint16_t a, uint16_t b) {
return (a < b) ? a : b;
}
static inline uint16_t lfs_max16(uint16_t a, uint16_t b) {
return (a > b) ? a : b;
}
// Clamp is useful as the logic for min/max when clamping can become confusing
static inline uint32_t lfs_clamp32(uint32_t a, uint32_t min, uint32_t max) {
return lfs_min32(lfs_max32(a, min), max);
}
static inline int32_t lfs_sclamp32(int32_t a, int32_t min, int32_t max) {
return lfs_smin32(lfs_smax32(a, min), max);
}
// Absolute value of signed numbers
static inline int32_t lfs_abs32(int32_t a) {
return (a < 0) ? -a : a;
}
// TODO how many of these do we actually need
// Swap two 16-bit numbers
static inline void lfs_swap16(uint16_t *a, uint16_t *b) {
uint16_t t = *a;
*a = *b;
*b = t;
}
static inline void lfs_sswap16(int16_t *a, int16_t *b) {
int16_t t = *a;
*a = *b;
*b = t;
}
// Swap two 32-bit numbers
static inline void lfs_swap32(uint32_t *a, uint32_t *b) {
uint32_t t = *a;
*a = *b;
*b = t;
}
static inline void lfs_sswap32(int32_t *a, int32_t *b) {
int32_t t = *a;
*a = *b;
*b = t;
}
// 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);
}
// 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;
}
// 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);
// Calculate crc32c incrementally
//
// polynomial = 0x11edc6f41
// init = 0xffffffff
// fini = 0xffffffff
//
uint32_t lfs_crc32c(uint32_t crc, const void *buffer, size_t size);
// 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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