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, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 * 22 * Copyright 2000 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 #ifndef _CRCMODEL_H 27 #define _CRCMODEL_H 28 29 #pragma ident "%Z%%M% %I% %E% SMI" 30 31 #ifdef SOLARIS_UNIX 32 #include <sys/types.h> 33 #else 34 typedef long uint32_t; 35 #endif 36 37 #ifdef __cplusplus 38 extern "C" { 39 #endif 40 41 /* 42 * 43 * Start of crcmodel.h 44 * 45 * 46 * Author : Ross Williams (ross@guest.adelaide.edu.au.). 47 * Date : 3 June 1993. 48 * Status : Public domain. 49 * 50 * Description : This is the header (.h) file for the reference 51 * implementation of the Rocksoft^tm Model CRC Algorithm. For more 52 * information on the Rocksoft^tm Model CRC Algorithm, see the document 53 * titled "A Painless Guide to CRC Error Detection Algorithms" by Ross 54 * Williams (ross@guest.adelaide.edu.au.). This document is likely to be in 55 * "ftp.adelaide.edu.au/pub/rocksoft". 56 * 57 * Note: Rocksoft is a trademark of Rocksoft Pty Ltd, Adelaide, Australia. 58 * 59 * 60 * 61 * How to Use This Package 62 * ----------------------- 63 * Step 1: Declare a variable of type cm_t. Declare another variable 64 * (p_cm say) of type p_cm_t and initialize it to point to the first 65 * variable (e.g. p_cm_t p_cm = &cm_t). 66 * 67 * Step 2: Assign values to the parameter fields of the structure. 68 * If you don't know what to assign, see the document cited earlier. 69 * For example: 70 * p_cm->cm_width = 16; 71 * p_cm->cm_poly = 0x8005L; 72 * p_cm->cm_init = 0L; 73 * p_cm->cm_refin = TRUE; 74 * p_cm->cm_refot = TRUE; 75 * p_cm->cm_xorot = 0L; 76 * Note: Poly is specified without its top bit (18005 becomes 8005). 77 * Note: Width is one bit less than the raw poly width. 78 * 79 * Step 3: Initialize the instance with a call cm_ini(p_cm); 80 * 81 * Step 4: Process zero or more message bytes by placing zero or more 82 * successive calls to cm_nxt. Example: cm_nxt(p_cm,ch); 83 * 84 * Step 5: Extract the CRC value at any time by calling crc = cm_crc(p_cm); 85 * If the CRC is a 16-bit value, it will be in the bottom 16 bits. 86 * 87 * 88 * 89 * Design Notes 90 * ------------ 91 * PORTABILITY: This package has been coded very conservatively so that 92 * it will run on as many machines as possible. For example, all external 93 * identifiers have been restricted to 6 characters and all internal ones to 94 * 8 characters. The prefix cm (for Crc Model) is used as an attempt to avoid 95 * namespace collisions. This package is endian independent. 96 * 97 * EFFICIENCY: This package (and its interface) is not designed for 98 * speed. The purpose of this package is to act as a well-defined reference 99 * model for the specification of CRC algorithms. If you want speed, cook up 100 * a specific table-driven implementation as described in the document cited 101 * above. This package is designed for validation only; if you have found or 102 * implemented a CRC algorithm and wish to describe it as a set of parameters 103 * to the Rocksoft^tm Model CRC Algorithm, your CRC algorithm implementation 104 * should behave identically to this package under those parameters. 105 * 106 */ 107 108 109 /* The following definitions are extracted from my style header file which */ 110 /* would be cumbersome to distribute with this package. The DONE_STYLE is the */ 111 /* idempotence symbol used in my style header file. */ 112 113 #ifndef DONE_STYLE 114 115 typedef unsigned bool; 116 typedef unsigned char *p_ubyte_; 117 118 #ifndef TRUE 119 #define FALSE 0 120 #define TRUE 1 121 #endif 122 123 /* Change to the second definition if you don't have prototypes. */ 124 #define P_(A) A 125 /* #define P_(A) () */ 126 127 /* Uncomment this definition if you don't have void. */ 128 /* typedef int void; */ 129 130 #endif 131 132 /* CRC Model Abstract Type */ 133 /* ----------------------- */ 134 /* The following type stores the context of an executing instance of the */ 135 /* model algorithm. Most of the fields are model parameters which must be */ 136 /* set before the first initializing call to cm_ini. */ 137 typedef struct 138 { 139 int cm_width; /* Parameter: Width in bits [8,32]. */ 140 uint32_t cm_poly; /* Parameter: The algorithm's polynomial. */ 141 uint32_t cm_init; /* Parameter: Initial register value. */ 142 bool cm_refin; /* Parameter: Reflect input bytes? */ 143 bool cm_refot; /* Parameter: Reflect output CRC? */ 144 uint32_t cm_xorot; /* Parameter: XOR this to output CRC. */ 145 146 uint32_t cm_reg; /* Context: Context during execution. */ 147 } cm_t; 148 typedef cm_t *p_cm_t; 149 150 /* Functions That Implement The Model */ 151 /* ---------------------------------- */ 152 /* The following functions animate the cm_t abstraction. */ 153 154 void cm_ini P_((p_cm_t p_cm)); 155 /* Initializes the argument CRC model instance. */ 156 /* All parameter fields must be set before calling this. */ 157 158 void cm_nxt P_((p_cm_t p_cm, int ch)); 159 /* Processes a single message byte [0,255]. */ 160 161 void cm_blk P_((p_cm_t p_cm, p_ubyte_ blk_adr, uint32_t blk_len)); 162 /* Processes a block of message bytes. */ 163 164 uint32_t cm_crc P_((p_cm_t p_cm)); 165 /* Returns the CRC value for the message bytes processed so far. */ 166 167 /* Functions For Table Calculation */ 168 /* ------------------------------- */ 169 /* The following function can be used to calculate a CRC lookup table. */ 170 /* It can also be used at run-time to create or check static tables. */ 171 172 uint32_t cm_tab P_((p_cm_t p_cm, int index)); 173 /* Returns the i'th entry for the lookup table for the specified algorithm. */ 174 /* The function examines the fields cm_width, cm_poly, cm_refin, and the */ 175 /* argument table index in the range [0,255] and returns the table entry in */ 176 /* the bottom cm_width bytes of the return value. */ 177 178 #ifdef __cplusplus 179 } 180 #endif 181 182 #endif /* _CRCMODEL_H */ 183