diff options
| author | David Oberhollenzer <david.oberhollenzer@sigma-star.at> | 2019-07-26 22:31:55 +0200 |
|---|---|---|
| committer | David Oberhollenzer <david.oberhollenzer@sigma-star.at> | 2019-07-28 16:33:57 +0200 |
| commit | 0f1bedc90f4cb71d965e99446cf3e72a45909346 (patch) | |
| tree | 51da6f4ee75cffa160598b5425851a2cc5452933 /lib | |
| parent | 68591ef78ceefb9a37eb1744be73e646f63e450b (diff) | |
Add utility function to compute crc32 check sums
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Makemodule.am | 2 | ||||
| -rw-r--r-- | lib/util/crc32.c | 31 |
2 files changed, 32 insertions, 1 deletions
diff --git a/lib/Makemodule.am b/lib/Makemodule.am index 218adcd..5f0cdae 100644 --- a/lib/Makemodule.am +++ b/lib/Makemodule.am @@ -44,7 +44,7 @@ libutil_a_SOURCES += lib/util/read_data.c include/util.h libutil_a_SOURCES += lib/util/print_version.c lib/util/mkdir_p.c libutil_a_SOURCES += lib/util/str_table.c include/str_table.h libutil_a_SOURCES += lib/util/dirstack.c lib/util/padd_file.c -libutil_a_SOURCES += lib/util/read_data_at.c +libutil_a_SOURCES += lib/util/read_data_at.c lib/util/crc32.c if WITH_GZIP libcompress_a_SOURCES += lib/comp/gzip.c diff --git a/lib/util/crc32.c b/lib/util/crc32.c new file mode 100644 index 0000000..ffe0044 --- /dev/null +++ b/lib/util/crc32.c @@ -0,0 +1,31 @@ +/* SPDX-License-Identifier: GPL-3.0-or-later */ +#include "config.h" +#include "util.h" + +/* + Karl Malbrain's compact CRC-32. See "A compact CCITT crc16 and crc32 C + implementation that balances processor cache usage against speed" + */ +static const uint32_t s_crc32[16] = { + 0x00000000, 0x1DB71064, 0x3B6E20C8, 0x26D930AC, + 0x76DC4190, 0x6B6B51F4, 0x4DB26158, 0x5005713C, + 0xEDB88320, 0xF00F9344, 0xD6D6A3E8, 0xCB61B38C, + 0x9B64C2B0, 0x86D3D2D4, 0xA00AE278, 0xBDBDF21C +}; + +uint32_t update_crc32(uint32_t crc, const void *data, size_t size) +{ + const uint8_t *ptr = data; + uint8_t b; + + crc = ~crc; + + while (size--) { + b = *ptr++; + + crc = (crc >> 4) ^ s_crc32[(crc & 0x0F) ^ (b & 0x0F)]; + crc = (crc >> 4) ^ s_crc32[(crc & 0x0F) ^ (b >> 4)]; + } + + return ~crc; +} |