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