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libc/misc/crc32: crc32 add slow mode, optional decrease size

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Signed-off-by: buxiasen <buxiasen@xiaomi.com>
This commit is contained in:
buxiasen 2024-09-06 21:41:33 +08:00 committed by Mateusz Szafoni
parent 08949dec66
commit fba0324bd7
2 changed files with 29 additions and 1 deletions
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6
libs/libc/misc/Kconfig
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@ -11,6 +11,12 @@ config LIBC_CRC64_FAST
---help---
Enable the CRC64 lookup table to compute the CRC64 faster.
config LIBC_CRC32_SLOW
bool "CRC32 not use table to decrease rodata size"
default n
---help---
Optional disable the CRC32 lookup table to decrease rodata usage.
config LIBC_KBDCODEC
bool "Keyboard CODEC"
default n

24
libs/libc/misc/lib_crc32.c
View File

@ -52,6 +52,9 @@
* Private Data
************************************************************************************************/
#ifdef CONFIG_LIBC_CRC32_SLOW
# define LIBC_CRC32_POLY 0xedb88320
#else
static const uint32_t crc32_tab[] =
{
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
@ -87,6 +90,7 @@ static const uint32_t crc32_tab[] =
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};
#endif
/************************************************************************************************
* Public Functions
@ -103,11 +107,29 @@ static const uint32_t crc32_tab[] =
uint32_t crc32part(FAR const uint8_t *src, size_t len, uint32_t crc32val)
{
size_t i;
#ifdef CONFIG_LIBC_CRC32_SLOW
for (i = 0; i < len; i++)
{
size_t j;
crc32val ^= src[i];
for (j = 0; j < 8; j++)
{
if (crc32val & 1)
{
crc32val = (crc32val >> 1) ^ LIBC_CRC32_POLY;
}
else
{
crc32val = crc32val >> 1;
}
}
}
#else
for (i = 0; i < len; i++)
{
crc32val = crc32_tab[(crc32val & 0xff) ^ src[i]] ^ (crc32val >> 8);
}
#endif
return crc32val;
}