aboutsummaryrefslogtreecommitdiffstats
path: root/gpxe/src/crypto/crc32.c
diff options
context:
space:
mode:
Diffstat (limited to 'gpxe/src/crypto/crc32.c')
-rw-r--r--gpxe/src/crypto/crc32.c54
1 files changed, 54 insertions, 0 deletions
diff --git a/gpxe/src/crypto/crc32.c b/gpxe/src/crypto/crc32.c
new file mode 100644
index 00000000..0cc314e8
--- /dev/null
+++ b/gpxe/src/crypto/crc32.c
@@ -0,0 +1,54 @@
+/*
+ * Little-endian CRC32 implementation.
+ *
+ * Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <gpxe/crc32.h>
+
+#define CRCPOLY 0xedb88320
+
+/**
+ * Calculate 32-bit little-endian CRC checksum
+ *
+ * @v seed Initial value
+ * @v data Data to checksum
+ * @v len Length of data
+ *
+ * Usually @a seed is initially zero or all one bits, depending on the
+ * protocol. To continue a CRC checksum over multiple calls, pass the
+ * return value from one call as the @a seed parameter to the next.
+ */
+u32 crc32_le ( u32 seed, const void *data, size_t len )
+{
+ u32 crc = seed;
+ const u8 *src = data;
+ u32 mult;
+ int i;
+
+ while ( len-- ) {
+ crc ^= *src++;
+ for ( i = 0; i < 8; i++ ) {
+ mult = ( crc & 1 ) ? CRCPOLY : 0;
+ crc = ( crc >> 1 ) ^ mult;
+ }
+ }
+
+ return crc;
+}