diff options
| -rw-r--r-- | include/linux/crc16.h | 44 | ||||
| -rw-r--r-- | lib/Kconfig | 8 | ||||
| -rw-r--r-- | lib/Makefile | 3 | ||||
| -rw-r--r-- | lib/crc16.c | 67 |
4 files changed, 121 insertions, 1 deletions
diff --git a/include/linux/crc16.h b/include/linux/crc16.h new file mode 100644 index 0000000..bdedf82 --- /dev/null +++ b/include/linux/crc16.h @@ -0,0 +1,44 @@ +/* + * crc16.h - CRC-16 routine + * + * Implements the standard CRC-16, as used with 1-wire devices: + * Width 16 + * Poly 0x8005 (x^16 + x^15 + x^2 + 1) + * Init 0 + * + * For 1-wire devices, the CRC is stored inverted, LSB-first + * + * Example buffer with the CRC attached: + * 31 32 33 34 35 36 37 38 39 C2 44 + * + * The CRC over a buffer with the CRC attached is 0xB001. + * So, if (crc16(0, buf, size) == 0xB001) then the buffer is valid. + * + * Refer to "Application Note 937: Book of iButton Standards" for details. + * http://www.maxim-ic.com/appnotes.cfm/appnote_number/937 + * + * Copyright (c) 2005 Ben Gardner <bgardner@wabtec.com> + * + * This source code is licensed under the GNU General Public License, + * Version 2. See the file COPYING for more details. + */ + +#ifndef __CRC16_H +#define __CRC16_H + +#include <linux/types.h> + +#define CRC16_INIT 0 +#define CRC16_VALID 0xb001 + +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 data) +{ + return (crc >> 8) ^ crc16_table[(crc ^ data) & 0xff]; +} + +#endif /* __CRC16_H */ + diff --git a/lib/Kconfig b/lib/Kconfig index e43197e..3de9335 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -12,6 +12,14 @@ config CRC_CCITT the kernel tree does. Such modules that use library CRC-CCITT functions require M here. +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" default y diff --git a/lib/Makefile b/lib/Makefile index 3e2bd0d..d9c38ba 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -23,11 +23,12 @@ lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o -ifneq ($(CONFIG_HAVE_DEC_LOCK),y) +ifneq ($(CONFIG_HAVE_DEC_LOCK),y) lib-y += dec_and_lock.o endif obj-$(CONFIG_CRC_CCITT) += crc-ccitt.o +obj-$(CONFIG_CRC16) += crc16.o obj-$(CONFIG_CRC32) += crc32.o obj-$(CONFIG_LIBCRC32C) += libcrc32c.o obj-$(CONFIG_GENERIC_IOMAP) += iomap.o diff --git a/lib/crc16.c b/lib/crc16.c new file mode 100644 index 0000000..011fe57 --- /dev/null +++ b/lib/crc16.c @@ -0,0 +1,67 @@ +/* + * crc16.c + * + * 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> + +/** CRC table for the CRC-16. The poly is 0x8005 (x^16 + x^15 + x^2 + 1) */ +u16 const crc16_table[256] = { + 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241, + 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440, + 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40, + 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841, + 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40, + 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41, + 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641, + 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040, + 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240, + 0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441, + 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41, + 0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840, + 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41, + 0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40, + 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640, + 0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041, + 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240, + 0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441, + 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41, + 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840, + 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41, + 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40, + 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640, + 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041, + 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241, + 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440, + 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40, + 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841, + 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40, + 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41, + 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641, + 0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040 +}; +EXPORT_SYMBOL(crc16_table); + +/** + * Compute the CRC-16 for the data buffer + * + * @param crc previous CRC value + * @param buffer data pointer + * @param len number of bytes in the buffer + * @return the updated CRC value + */ +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"); + |