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Subject[PATCH] crc16 consolidation (common part)
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Hi all, 

currently in the linux kernel we have 5 copies of same crc16 table.

Attached patch (applies to 2.5.59 cleanly) creates common crc16
computation module, which will be used by subsequent patches
for async ppp, irda and isdn subsystems.

Please consider applying.

Best regards.

--
Andrey Panin | Embedded systems software developer
pazke@orbita1.ru | PGP key: wwwkeys.pgp.net
diff -urN -X /usr/share/dontdiff linux-2.5.53.vanilla/include/linux/crc16.h linux-2.5.53/include/linux/crc16.h
--- linux-2.5.53.vanilla/include/linux/crc16.h Thu Jan 1 03:00:00 1970
+++ linux-2.5.53/include/linux/crc16.h Mon Dec 30 12:41:31 2002
@@ -0,0 +1,15 @@
+#ifndef _LINUX_CRC16_H
+#define _LINUX_CRC16_H
+
+#include <linux/types.h>
+
+extern u16 const crc16_table[256];
+
+extern u16 crc16(u16 crc, const u8 *buffer, size_t len);
+
+static inline u16 crc16_byte(u16 crc, const u8 c)
+{
+ return (crc >> 8) ^ crc16_table[(crc ^ c) & 0xff];
+}
+
+#endif /* _LINUX_CRC16_H */
diff -urN -X /usr/share/dontdiff linux-2.5.53.vanilla/lib/Kconfig linux-2.5.53/lib/Kconfig
--- linux-2.5.53.vanilla/lib/Kconfig Fri Dec 27 19:48:27 2002
+++ linux-2.5.53/lib/Kconfig Mon Dec 30 12:51:39 2002
@@ -4,6 +4,14 @@

menu "Library routines"

+config CRC16
+ tristate "CRC16 functions"
+ help
+ This option is provided for the case where no in-kernel-tree
+ modules require CRC16 functions, but a module built outside the
+ kernel tree does. Such modules that use library CRC16 functions
+ require M here.
+
config CRC32
tristate "CRC32 functions"
help
diff -urN -X /usr/share/dontdiff linux-2.5.53.vanilla/lib/Makefile linux-2.5.53/lib/Makefile
--- linux-2.5.53.vanilla/lib/Makefile Fri Dec 27 19:48:25 2002
+++ linux-2.5.53/lib/Makefile Mon Dec 30 12:56:35 2002
@@ -22,6 +22,7 @@
obj-y += dec_and_lock.o
endif

+obj-$(CONFIG_CRC16) += crc16.o
obj-$(CONFIG_CRC32) += crc32.o

obj-$(CONFIG_ZLIB_INFLATE) += zlib_inflate/
diff -urN -X /usr/share/dontdiff linux-2.5.53.vanilla/lib/crc16.c linux-2.5.53/lib/crc16.c
--- linux-2.5.53.vanilla/lib/crc16.c Thu Jan 1 03:00:00 1970
+++ linux-2.5.53/lib/crc16.c Mon Dec 30 12:51:58 2002
@@ -0,0 +1,69 @@
+/*
+ * linux/lib/crc16.c
+ *
+ * CRC-CCITT (x^16 + x^12 + x^5 + 1) computation
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/crc16.h>
+
+/*
+ * This mysterious table is just the CRC of each possible byte. It can be
+ * computed using the standard bit-at-a-time methods. The polynomial can
+ * be seen in entry 128, 0x8408. This corresponds to x^0 + x^5 + x^12.
+ * Add the implicit x^16, and you have the standard CRC-CCITT.
+ */
+u16 const crc16_table[256] = {
+ 0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
+ 0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
+ 0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
+ 0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
+ 0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
+ 0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
+ 0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
+ 0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
+ 0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
+ 0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
+ 0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
+ 0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
+ 0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
+ 0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
+ 0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
+ 0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
+ 0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
+ 0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
+ 0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
+ 0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
+ 0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
+ 0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
+ 0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
+ 0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
+ 0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
+ 0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
+ 0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
+ 0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
+ 0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
+ 0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
+ 0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
+ 0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
+};
+EXPORT_SYMBOL(crc16_table);
+
+/**
+ * crc16 - recompute the CRC for the data buffer
+ * @crc - previous CRC value
+ * @buffer - data pointer
+ * @len - number of bytes in the buffer
+ */
+u16 crc16(u16 crc, u8 const *buffer, size_t len)
+{
+ while (len--)
+ crc = crc16_byte(crc, *buffer++);
+ return crc;
+}
+EXPORT_SYMBOL(crc16);
+
+MODULE_DESCRIPTION("CRC16 calculations");
+MODULE_LICENSE("GPL");
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