From df9c15d40a50ed17baa7bdbb11ef6cca9d410cf3 Mon Sep 17 00:00:00 2001 From: zyp Date: Mon, 8 May 2006 13:23:20 +0000 Subject: [project @ zyp-20060508132320-2c118d1a7e2505db] [project @ 24] Converted from make to distutils. --- src/crc32.cpp | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 src/crc32.cpp (limited to 'src/crc32.cpp') diff --git a/src/crc32.cpp b/src/crc32.cpp new file mode 100644 index 0000000..55d6dd2 --- /dev/null +++ b/src/crc32.cpp @@ -0,0 +1,41 @@ +#include "crc32.h" + +int* CRC32::crc_table; + +int* CRC32::generate_table() { + int crc; + int* table = new int[256]; + for(int i = 0; i < 256; i++) { + crc = i << 24; + for(int j = 0; j < 8; j++) { + if(crc & 0x80000000) { + crc = (crc << 1) ^ 0x04c11db7; + } else { + crc = crc << 1; + } + } + table[i] = crc; + } + return table; +} + +int CRC32::reflect(int data, int bits) { + int x = 0; + for(int i = 0; i < bits; i++) { + x = x << 1; + x |= data & 1; + data = data >> 1; + } + return x; +} + +int CRC32::crc32(int crc, const char* data, int length) { + crc = ~reflect(crc, 32); + if(!crc_table) { + crc_table = generate_table(); + } + for (int i = 0; i < length; i++) { + crc = (crc << 8) ^ crc_table[((crc >> 24) ^ reflect(data[i], 8)) & 0xff]; + } + return ~reflect(crc, 32); +} -- cgit v1.2.3