From 58cf9ddb2ec2c9ba7285db00ee9c5ec896e05650 Mon Sep 17 00:00:00 2001 From: Bjorn Andersson Date: Thu, 2 Feb 2017 15:42:38 -0800 Subject: [PATCH] hdlc: Replace borrowed CRC implementation The CRC implementation previously included was borrowed from the Linux kernel, it's removed and instead a new implementation, based on [1], is introduced. [1] http://www.ross.net/crc/download/crc_v3.txt Signed-off-by: Bjorn Andersson --- Makefile | 2 +- crc_ccitt.c | 69 ----------------------------------------------------- crc_ccitt.h | 9 ------- diag.c | 6 ++--- hdlc.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++ hdlc.h | 6 +++++ 6 files changed, 78 insertions(+), 82 deletions(-) delete mode 100644 crc_ccitt.c delete mode 100644 crc_ccitt.h create mode 100644 hdlc.c create mode 100644 hdlc.h diff --git a/Makefile b/Makefile index 71f6e03..4373b2d 100644 --- a/Makefile +++ b/Makefile @@ -3,7 +3,7 @@ DIAG := diag CFLAGS := -Wall -g -O2 LDFLAGS := -ludev -SRCS := crc_ccitt.c diag.c diag_cntl.c mbuf.c peripheral.c util.c watch.c +SRCS := diag.c diag_cntl.c hdlc.c mbuf.c peripheral.c util.c watch.c OBJS := $(SRCS:.c=.o) $(DIAG): $(OBJS) diff --git a/crc_ccitt.c b/crc_ccitt.c deleted file mode 100644 index 2acf692..0000000 --- a/crc_ccitt.c +++ /dev/null @@ -1,69 +0,0 @@ -/* - * linux/lib/crc-ccitt.c - * - * This source code is licensed under the GNU General Public License, - * Version 2. See the file COPYING for more details. - */ -#include -#include - -#include "crc_ccitt.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. - */ -uint16_t const crc_ccitt_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 -}; - -uint16_t crc_ccitt_byte(uint16_t crc, const uint8_t c) -{ - return (crc >> 8) ^ crc_ccitt_table[(crc ^ c) & 0xff]; -} - -/** - * crc_ccitt - recompute the CRC for the data buffer - * @crc: previous CRC value - * @buffer: data pointer - * @len: number of bytes in the buffer - */ -uint16_t crc_ccitt(uint16_t crc, uint8_t const *buffer, size_t len) -{ - while (len--) - crc = crc_ccitt_byte(crc, *buffer++); - return crc; -} diff --git a/crc_ccitt.h b/crc_ccitt.h deleted file mode 100644 index 397314f..0000000 --- a/crc_ccitt.h +++ /dev/null @@ -1,9 +0,0 @@ -#ifndef __CRC_CCITT_H__ -#define __CRC_CCITT_H__ - -#define CRC_16_L_SEED 0xFFFF - -uint16_t crc_ccitt(uint16_t crc, uint8_t const *buffer, size_t len); -uint16_t crc_ccitt_byte(uint16_t crc, const uint8_t c); - -#endif diff --git a/diag.c b/diag.c index fbd4082..abc8d26 100644 --- a/diag.c +++ b/diag.c @@ -27,9 +27,9 @@ #include #include -#include "crc_ccitt.h" #include "diag.h" #include "diag_cntl.h" +#include "hdlc.h" #include "list.h" #include "mbuf.h" #include "peripheral.h" @@ -41,7 +41,7 @@ struct list_head diag_clients = LIST_INIT(diag_clients); static uint8_t *hdlc_encode(uint8_t *src, size_t slen, size_t *dlen) { - uint16_t crc = CRC_16_L_SEED; + uint16_t crc = 0xffff; uint8_t tmp[2]; uint8_t *dst; uint8_t *s = src; @@ -54,7 +54,7 @@ static uint8_t *hdlc_encode(uint8_t *src, size_t slen, size_t *dlen) d = dst; while (s < src + slen) { - crc = crc_ccitt_byte(crc, *s); + crc = hdlc_crc_byte(crc, *s); if (*s == 0x7d || *s == 0x7e) { *d++ = 0x7d; diff --git a/hdlc.c b/hdlc.c new file mode 100644 index 0000000..5ddfa19 --- /dev/null +++ b/hdlc.c @@ -0,0 +1,68 @@ +/* + * Copyright (c) 2017, Linaro Ltd. + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to + * deal in the Software without restriction, including without limitation the + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or + * sell copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + */ +#include +#include "hdlc.h" + +/* + * HDLC frame check is performed by a reversed CRC-CCITT-16 with polynomial + * x^16 + x^12 + x^5 + 1 (0x8408), an initial value of 0xffff and the result + * XORed with 0xffff. + * + * Calculation is performed with a table lookup as described in + * http://www.ross.net/crc/download/crc_v3.txt + */ +static uint16_t crc_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 +}; + +uint16_t hdlc_crc_byte(uint16_t crc, uint8_t ch) +{ + return (crc >> 8) ^ crc_table[(crc ^ ch) & 0xff]; +} diff --git a/hdlc.h b/hdlc.h new file mode 100644 index 0000000..e41b712 --- /dev/null +++ b/hdlc.h @@ -0,0 +1,6 @@ +#ifndef __HDLC_H__ +#define __HDLC_H__ + +uint16_t hdlc_crc_byte(uint16_t crc, uint8_t ch); + +#endif