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1 | /* model.c |
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2 | * Greg Cook, 24/Feb/2016 |
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3 | */ |
4 | |
5 | /* CRC RevEng, an arbitrary-precision CRC calculator and algorithm finder |
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6 | * Copyright (C) 2010, 2011, 2012, 2013, 2014, 2015, 2016 Gregory Cook |
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7 | * |
8 | * This file is part of CRC RevEng. |
9 | * |
10 | * CRC RevEng is free software: you can redistribute it and/or modify |
11 | * it under the terms of the GNU General Public License as published by |
12 | * the Free Software Foundation, either version 3 of the License, or |
13 | * (at your option) any later version. |
14 | * |
15 | * CRC RevEng is distributed in the hope that it will be useful, |
16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
18 | * GNU General Public License for more details. |
19 | * |
20 | * You should have received a copy of the GNU General Public License |
21 | * along with CRC RevEng. If not, see <http://www.gnu.org/licenses/>. |
22 | */ |
23 | |
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24 | /* 2016-06-22: split off preset.c |
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25 | * 2012-03-03: single-line Williams model string conversion |
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26 | * 2011-09-03: added mrev(), mnovel() |
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27 | * 2011-01-17: fixed ANSI C warnings (except preset models) |
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28 | * 2010-12-26: renamed CRC RevEng |
29 | * 2010-12-18: minor change to mtostr() output format |
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30 | * 2010-12-15: added mcmp() |
31 | * 2010-12-14: finished mtostr() |
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32 | * 2010-12-12: started models.c |
33 | */ |
34 | |
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35 | #include <stdio.h> |
36 | #include <stdlib.h> |
37 | #include <string.h> |
38 | #include "reveng.h" |
39 | |
40 | /* Private declarations */ |
41 | |
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42 | static const poly_t pzero = PZERO; |
43 | |
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44 | /* Definitions */ |
45 | |
46 | void |
47 | mcpy(model_t *dest, const model_t *src) { |
48 | /* Copies the parameters of src to dest. |
49 | * dest must be an initialised model. |
50 | */ |
51 | if(!dest || !src) return; |
52 | pcpy(&dest->spoly, src->spoly); |
53 | pcpy(&dest->init, src->init); |
54 | pcpy(&dest->xorout, src->xorout); |
55 | pcpy(&dest->check, src->check); |
56 | dest->flags = src->flags; |
57 | /* link to the name as it is static */ |
58 | dest->name = src->name; |
59 | } |
60 | |
61 | void |
62 | mfree(model_t *model) { |
63 | /* Frees the parameters of model. */ |
64 | if(!model) return; |
65 | pfree(&model->spoly); |
66 | pfree(&model->init); |
67 | pfree(&model->xorout); |
68 | pfree(&model->check); |
69 | /* not name as it is static */ |
70 | /* not model either, it might point to an array! */ |
71 | } |
72 | |
73 | int |
74 | mcmp(const model_t *a, const model_t *b) { |
75 | /* Compares a and b for identical effect, i.e. disregarding |
76 | * trailing zeroes in parameter polys. |
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77 | * Intended for bsearch(). |
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78 | */ |
79 | int result; |
80 | if(!a || !b) return(!b - !a); |
81 | if((result = psncmp(&a->spoly, &b->spoly))) return(result); |
82 | if((result = psncmp(&a->init, &b->init))) return(result); |
83 | if((a->flags & P_REFIN) && (~b->flags & P_REFIN)) return(1); |
84 | if((~a->flags & P_REFIN) && (b->flags & P_REFIN)) return(-1); |
85 | if((a->flags & P_REFOUT) && (~b->flags & P_REFOUT)) return(1); |
86 | if((~a->flags & P_REFOUT) && (b->flags & P_REFOUT)) return(-1); |
87 | return(psncmp(&a->xorout, &b->xorout)); |
88 | } |
89 | |
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90 | char * |
91 | mtostr(const model_t *model) { |
92 | /* Returns a malloc()-ed string containing a Williams model |
93 | * record representing the input model. |
94 | * mcanon() should be called on the argument before printing. |
95 | */ |
96 | size_t size; |
97 | char *polystr, *initstr, *xorotstr, *checkstr, strbuf[512], *string = NULL; |
98 | |
99 | if(!model) return(NULL); |
100 | polystr = ptostr(model->spoly, P_RTJUST, 4); |
101 | initstr = ptostr(model->init, P_RTJUST, 4); |
102 | xorotstr = ptostr(model->xorout, P_RTJUST, 4); |
103 | checkstr = ptostr(model->check, P_RTJUST, 4); |
104 | |
105 | sprintf(strbuf, "%lu", plen(model->spoly)); |
106 | size = |
107 | 70 |
108 | + (model->name && *model->name ? 2 + strlen(model->name) : 6) |
109 | + strlen(strbuf) |
110 | + (polystr && *polystr ? strlen(polystr) : 6) |
111 | + (initstr && *initstr ? strlen(initstr) : 6) |
112 | + (model->flags & P_REFIN ? 4 : 5) |
113 | + (model->flags & P_REFOUT ? 4 : 5) |
114 | + (xorotstr && *xorotstr ? strlen(xorotstr) : 6) |
115 | + (checkstr && *checkstr ? strlen(checkstr) : 6); |
116 | if((string = malloc(size))) { |
117 | sprintf(strbuf, "\"%s\"", model->name); |
118 | sprintf(string, |
119 | "width=%lu " |
120 | "poly=0x%s " |
121 | "init=0x%s " |
122 | "refin=%s " |
123 | "refout=%s " |
124 | "xorout=0x%s " |
125 | "check=0x%s " |
126 | "name=%s", |
127 | plen(model->spoly), |
128 | polystr && *polystr ? polystr : "(none)", |
129 | initstr && *initstr ? initstr : "(none)", |
130 | (model->flags & P_REFIN) ? "true" : "false", |
131 | (model->flags & P_REFOUT) ? "true" : "false", |
132 | xorotstr && *xorotstr ? xorotstr : "(none)", |
133 | checkstr && *checkstr ? checkstr : "(none)", |
134 | (model->name && *model->name) ? strbuf : "(none)"); |
135 | } |
136 | free(polystr); |
137 | free(initstr); |
138 | free(xorotstr); |
139 | free(checkstr); |
140 | if(!string) |
141 | uerror("cannot allocate memory for model description"); |
142 | return(string); |
143 | } |
144 | |
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145 | void |
146 | mcanon(model_t *model) { |
147 | /* canonicalise a model */ |
148 | unsigned long dlen; |
149 | |
150 | if(!model) return; |
151 | |
152 | /* extending on the right here. This preserves the functionality |
153 | * of a presumed working model. |
154 | */ |
155 | psnorm(&model->spoly); |
156 | dlen = plen(model->spoly); |
157 | praloc(&model->init, dlen); |
158 | praloc(&model->xorout, dlen); |
159 | |
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160 | /* only calculate Check if missing. Relying on all functions |
161 | * changing parameters to call mnovel(). This is to ensure that |
162 | * the Check value stored in the preset table is printed when |
163 | * the model is dumped. If something goes wrong with the |
164 | * calculator then the discrepancy with the stored Check value |
165 | * might be noticed. Storing the Check value with each preset |
166 | * is highly preferred. |
167 | */ |
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168 | if(!plen(model->check)) |
169 | mcheck(model); |
170 | } |
171 | |
172 | void |
173 | mcheck(model_t *model) { |
174 | /* calculate a check for the model */ |
175 | poly_t checkstr, check; |
176 | |
177 | /* generate the check string with the correct bit order */ |
178 | checkstr = strtop("313233343536373839", model->flags, 8); |
179 | check = pcrc(checkstr, model->spoly, model->init, pzero, model->flags); |
180 | if(model->flags & P_REFOUT) |
181 | prev(&check); |
182 | psum(&check, model->xorout, 0UL); |
183 | model->check = check; |
184 | pfree(&checkstr); |
185 | } |
186 | |
187 | void |
188 | mrev(model_t *model) { |
189 | /* reverse the model to calculate reversed CRCs */ |
190 | /* Here we invert RefIn and RefOut so that the user need only |
191 | * reverse the order of characters in the arguments, not the |
192 | * characters themselves. If RefOut=True, the mirror image of |
193 | * Init seen through RefOut becomes XorOut, and as RefOut |
194 | * becomes false, the XorOut value moved to Init stays upright. |
195 | * If RefOut=False, Init transfers to XorOut without reflection |
196 | * but the new Init must be reflected to present the same image, |
197 | * as RefOut becomes true. |
198 | */ |
199 | poly_t temp; |
200 | |
201 | prcp(&model->spoly); |
202 | if(model->flags & P_REFOUT) |
203 | prev(&model->init); |
204 | else |
205 | prev(&model->xorout); |
206 | |
207 | /* exchange init and xorout */ |
208 | temp = model->init; |
209 | model->init = model->xorout; |
210 | model->xorout = temp; |
211 | |
212 | /* invert refin and refout */ |
213 | model->flags ^= P_REFIN | P_REFOUT; |
214 | |
215 | mnovel(model); |
216 | } |
217 | |
218 | void |
219 | mnovel(model_t *model) { |
220 | /* remove name and check string from modified model */ |
221 | model->name = NULL; |
222 | pfree(&model->check); |
223 | } |