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Fixed issue with big-endian CTZ lists intertwined in commit logic

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Found while testing big-endian support. Basically, if littlefs is really
really unlucky, the block allocator could kick in while committing a
file's CTZ reference. If this happens, the block allocator will need to
traverse all CTZ skip-lists in memory, including the skip-list we're
committing. This means we can't convert the CTZ's endianness in place,
and need to make a copy on big-endian systems.

We rely on dead-code elimination from the compiler to make the
conditional behaviour for big-endian vs little-endian system a noop
determined by the lfs_tole32 intrinsic.
This commit is contained in:
Christopher Haster
2018-08-08 09:37:43 -05:00
parent 10f45ac02f
commit 20b669a23d
2 changed files with 18 additions and 16 deletions
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22
lfs_util.h
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@@ -11,8 +11,8 @@
// 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.
// 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
@@ -88,6 +88,15 @@ static inline uint32_t lfs_min(uint32_t a, uint32_t b) {
return (a < b) ? a : b;
}
// 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 next smallest power of 2 less than or equal to a
static inline uint32_t lfs_npw2(uint32_t a) {
#if !defined(LFS_NO_INTRINSICS) && (defined(__GNUC__) || defined(__CC_ARM))
@@ -177,15 +186,6 @@ static inline uint16_t lfs_tole16(uint16_t a) {
return lfs_fromle16(a);
}
// 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);
}
// Calculate CRC-32 with polynomial = 0x04c11db7
uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size);