1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #ifndef _CRCMODEL_H 28 #define _CRCMODEL_H 29 30 #ifdef SOLARIS_UNIX 31 #include <sys/types.h> 32 #else 33 typedef long uint32_t; 34 #endif 35 36 #ifdef __cplusplus 37 extern "C" { 38 #endif 39 40 /* 41 * 42 * Start of crcmodel.h 43 * 44 * 45 * Author : Ross Williams (ross@guest.adelaide.edu.au.). 46 * Date : 3 June 1993. 47 * Status : Public domain. 48 * 49 * Description : This is the header (.h) file for the reference 50 * implementation of the Rocksoft^tm Model CRC Algorithm. For more 51 * information on the Rocksoft^tm Model CRC Algorithm, see the document 52 * titled "A Painless Guide to CRC Error Detection Algorithms" by Ross 53 * Williams (ross@guest.adelaide.edu.au.). This document is likely to be in 54 * "ftp.adelaide.edu.au/pub/rocksoft". 55 * 56 * Note: Rocksoft is a trademark of Rocksoft Pty Ltd, Adelaide, Australia. 57 * 58 * 59 * 60 * How to Use This Package 61 * ----------------------- 62 * Step 1: Declare a variable of type cm_t. Declare another variable 63 * (p_cm say) of type p_cm_t and initialize it to point to the first 64 * variable (e.g. p_cm_t p_cm = &cm_t). 65 * 66 * Step 2: Assign values to the parameter fields of the structure. 67 * If you don't know what to assign, see the document cited earlier. 68 * For example: 69 * p_cm->cm_width = 16; 70 * p_cm->cm_poly = 0x8005L; 71 * p_cm->cm_init = 0L; 72 * p_cm->cm_refin = TRUE; 73 * p_cm->cm_refot = TRUE; 74 * p_cm->cm_xorot = 0L; 75 * Note: Poly is specified without its top bit (18005 becomes 8005). 76 * Note: Width is one bit less than the raw poly width. 77 * 78 * Step 3: Initialize the instance with a call cm_ini(p_cm); 79 * 80 * Step 4: Process zero or more message bytes by placing zero or more 81 * successive calls to cm_nxt. Example: cm_nxt(p_cm,ch); 82 * 83 * Step 5: Extract the CRC value at any time by calling crc = cm_crc(p_cm); 84 * If the CRC is a 16-bit value, it will be in the bottom 16 bits. 85 * 86 * 87 * 88 * Design Notes 89 * ------------ 90 * PORTABILITY: This package has been coded very conservatively so that 91 * it will run on as many machines as possible. For example, all external 92 * identifiers have been restricted to 6 characters and all internal ones to 93 * 8 characters. The prefix cm (for Crc Model) is used as an attempt to avoid 94 * namespace collisions. This package is endian independent. 95 * 96 * EFFICIENCY: This package (and its interface) is not designed for 97 * speed. The purpose of this package is to act as a well-defined reference 98 * model for the specification of CRC algorithms. If you want speed, cook up 99 * a specific table-driven implementation as described in the document cited 100 * above. This package is designed for validation only; if you have found or 101 * implemented a CRC algorithm and wish to describe it as a set of parameters 102 * to the Rocksoft^tm Model CRC Algorithm, your CRC algorithm implementation 103 * should behave identically to this package under those parameters. 104 * 105 */ 106 107 108 /* The following definitions are extracted from my style header file which */ 109 /* would be cumbersome to distribute with this package. The DONE_STYLE is the */ 110 /* idempotence symbol used in my style header file. */ 111 112 #ifndef DONE_STYLE 113 114 typedef unsigned bool; 115 typedef unsigned char *p_ubyte_; 116 117 #ifndef TRUE 118 #define FALSE 0 119 #define TRUE 1 120 #endif 121 122 /* Change to the second definition if you don't have prototypes. */ 123 #define P_(A) A 124 /* #define P_(A) () */ 125 126 /* Uncomment this definition if you don't have void. */ 127 /* typedef int void; */ 128 129 #endif 130 131 /* CRC Model Abstract Type */ 132 /* ----------------------- */ 133 /* The following type stores the context of an executing instance of the */ 134 /* model algorithm. Most of the fields are model parameters which must be */ 135 /* set before the first initializing call to cm_ini. */ 136 typedef struct 137 { 138 int cm_width; /* Parameter: Width in bits [8,32]. */ 139 uint32_t cm_poly; /* Parameter: The algorithm's polynomial. */ 140 uint32_t cm_init; /* Parameter: Initial register value. */ 141 bool cm_refin; /* Parameter: Reflect input bytes? */ 142 bool cm_refot; /* Parameter: Reflect output CRC? */ 143 uint32_t cm_xorot; /* Parameter: XOR this to output CRC. */ 144 145 uint32_t cm_reg; /* Context: Context during execution. */ 146 } cm_t; 147 typedef cm_t *p_cm_t; 148 149 /* Functions That Implement The Model */ 150 /* ---------------------------------- */ 151 /* The following functions animate the cm_t abstraction. */ 152 153 void cm_ini P_((p_cm_t p_cm)); 154 /* Initializes the argument CRC model instance. */ 155 /* All parameter fields must be set before calling this. */ 156 157 void cm_nxt P_((p_cm_t p_cm, int ch)); 158 /* Processes a single message byte [0,255]. */ 159 160 void cm_blk P_((p_cm_t p_cm, p_ubyte_ blk_adr, uint32_t blk_len)); 161 /* Processes a block of message bytes. */ 162 163 uint32_t cm_crc P_((p_cm_t p_cm)); 164 /* Returns the CRC value for the message bytes processed so far. */ 165 166 /* Functions For Table Calculation */ 167 /* ------------------------------- */ 168 /* The following function can be used to calculate a CRC lookup table. */ 169 /* It can also be used at run-time to create or check static tables. */ 170 171 uint32_t cm_tab P_((p_cm_t p_cm, int index)); 172 /* Returns the i'th entry for the lookup table for the specified algorithm. */ 173 /* The function examines the fields cm_width, cm_poly, cm_refin, and the */ 174 /* argument table index in the range [0,255] and returns the table entry in */ 175 /* the bottom cm_width bytes of the return value. */ 176 177 #ifdef __cplusplus 178 } 179 #endif 180 181 #endif /* _CRCMODEL_H */ 182