From 0f1bedc90f4cb71d965e99446cf3e72a45909346 Mon Sep 17 00:00:00 2001 From: David Oberhollenzer Date: Fri, 26 Jul 2019 22:31:55 +0200 Subject: Add utility function to compute crc32 check sums Signed-off-by: David Oberhollenzer --- lib/util/crc32.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) create mode 100644 lib/util/crc32.c (limited to 'lib/util/crc32.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; +} -- cgit v1.2.3