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Changed lfs_crc to match more common API

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In looking at the common CRC APIs out there, this seemed the most
common. At least more common than the current modified-in-place pointer
API. It also seems to have a slightly better code footprint. I'm blaming
pointer optimization issues.

One downside is that lfs_crc can't report errors, however it was already
assumed that lfs_crc can not error.
This commit is contained in:
Christopher Haster
2018-08-07 14:59:44 -05:00
parent 3b3981eb74
commit 10f45ac02f
3 changed files with 17 additions and 15 deletions
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lfs_util.c
+5 -3
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@@ -11,7 +11,7 @@
// Software CRC implementation with small lookup table
void lfs_crc(uint32_t *restrict crc, const void *buffer, size_t size) {
uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size) {
static const uint32_t rtable[16] = {
0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
@@ -22,9 +22,11 @@ void lfs_crc(uint32_t *restrict crc, const void *buffer, size_t size) {
const uint8_t *data = buffer;
for (size_t i = 0; i < size; i++) {
*crc = (*crc >> 4) ^ rtable[(*crc ^ (data[i] >> 0)) & 0xf];
*crc = (*crc >> 4) ^ rtable[(*crc ^ (data[i] >> 4)) & 0xf];
crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 0)) & 0xf];
crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 4)) & 0xf];
}
return crc;
}