1 files changed, 83 insertions, 0 deletions
diff --git a/ubi-utils/src/crc32.c b/ubi-utils/src/crc32.c
new file mode 100644
index 0000000..666e217
--- /dev/null
+++ b/ubi-utils/src/crc32.c
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+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * 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
+ * (at your option) 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.
+ *
+ * Author: Thomas Gleixner
+ */
+
+/*
+ * CRC32 functions
+ *
+ * Can be compiled as seperate object, but is included into the ipl source
+ * so gcc can inline the functions. We optimize for size so the omission of
+ * the function frame is helpful.
+ *
+ */
+
+#include <stdint.h>
+#include <crc32.h>
+
+/* CRC polynomial */
+#define CRC_POLY	0xEDB88320
+
+/**
+ * init_crc32_table - Initialize crc table
+ *
+ * @table:	pointer to the CRC table which must be initialized
+ *
+ * Create CRC32 table for given polynomial. The table is created with
+ * the lowest order term in the highest order bit. So the x^32 term
+ * has to implied in the crc calculation function.
+ */
+void init_crc32_table(uint32_t *table)
+{
+	uint32_t crc;
+	int i, j;
+
+	for (i = 0; i < 256; i++) {
+		crc = i;
+		for (j = 8; j > 0; j--) {
+			if (crc & 1)
+				crc = (crc >> 1) ^ CRC_POLY;
+			else
+				crc >>= 1;
+		}
+		table[i] = crc;
+	}
+}
+
+/**
+ * clc_crc32 - Calculate CRC32 over a buffer
+ *
+ * @table:	pointer to the CRC table
+ * @crc:	initial crc value
+ * @buf:	pointer to the buffer
+ * @len:	number of bytes to calc
+ *
+ * Returns the updated crc value.
+ *
+ * The algorithm resembles a hardware shift register, but calculates 8
+ * bit at once.
+ */
+uint32_t clc_crc32(uint32_t *table, uint32_t crc, void *buf,
+		   int len)
+{
+	const unsigned char *p = buf;
+
+	while(--len >= 0)
+		crc = table[(crc ^ *p++) & 0xff] ^ (crc >> 8);
+	return crc;
+}