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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: hex.c,v 1.3 2004/04/08 01:36:11 mdw Exp $ |
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4 | * |
5 | * Hexadecimal encoding and decoding. |
6 | * |
7 | * (c) 2001 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * mLib is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with mLib; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <stdio.h> |
33 | #include <stdlib.h> |
34 | #include <string.h> |
35 | |
36 | #include "dstr.h" |
37 | #include "hex.h" |
38 | |
39 | /*----- Important tables --------------------------------------------------*/ |
40 | |
41 | static const char encodemap[] = { "0123456789abcdef" }; |
42 | |
43 | static const signed char decodemap[] = { |
44 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x */ |
45 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 1x */ |
46 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 2x */ |
47 | 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, -1, -1, -1, -1, -1, /* 3x */ |
48 | -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 4x */ |
49 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 5x */ |
50 | -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 6x */ |
51 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 7x */ |
52 | }; |
53 | |
54 | /*----- Main code ---------------------------------------------------------*/ |
55 | |
56 | /* --- @hex_encode@ --- * |
57 | * |
58 | * Arguments: @hex_ctx *ctx@ = pointer to a context block |
59 | * @const void *p@ = pointer to a source buffer |
60 | * @size_t sz@ = size of the source buffer |
61 | * @dstr *d@ = pointer to destination string |
62 | * |
63 | * Returns: --- |
64 | * |
65 | * Use: Encodes a binary string in hex. |
66 | */ |
67 | |
68 | void hex_encode(hex_ctx *ctx, const void *p, size_t sz, dstr *d) |
69 | { |
70 | if (p) { |
71 | const unsigned char *src = p; |
72 | |
73 | while (sz) { |
74 | unsigned x = *src++; |
75 | sz--; |
76 | DPUTC(d, encodemap[(x >> 4) & 0xf]); |
77 | DPUTC(d, encodemap[(x >> 0) & 0xf]); |
78 | ctx->lnlen += 2; |
79 | if (ctx->maxline && ctx->lnlen >= ctx->maxline) { |
80 | dstr_puts(d, ctx->indent); |
81 | ctx->lnlen = 0; |
82 | } |
83 | } |
84 | } |
85 | } |
86 | |
87 | /* --- @hex_decode@ --- * |
88 | * |
89 | * Arguments: @hex_ctx *ctx@ = pointer to a context block |
90 | * @const void *p@ = pointer to a source buffer |
91 | * @size_t sz@ = size of the source buffer |
92 | * @dstr *d@ = pointer to destination string |
93 | * |
94 | * Returns: --- |
95 | * |
96 | * Use: Decodes a binary string in hex. Pass in a null source |
97 | * pointer when you thing you've finished. |
98 | */ |
99 | |
100 | void hex_decode(hex_ctx *ctx, const void *p, size_t sz, dstr *d) |
101 | { |
102 | if (p) { |
103 | unsigned long acc = ctx->acc; |
104 | unsigned qsz = ctx->qsz; |
105 | const char *src = p; |
106 | int ch; |
107 | |
108 | while (sz) { |
109 | |
110 | /* --- Get the next character and convert it --- */ |
111 | |
112 | ch = *src++; |
113 | if (ch >= 128 || ch < 0) |
114 | ch = -1; |
115 | else |
116 | ch = decodemap[ch]; |
117 | sz--; |
118 | if (ch == -1) |
119 | continue; |
120 | |
121 | /* --- Bung it in the accumulator --- */ |
122 | |
123 | acc = (acc << 4) | ch; |
124 | qsz++; |
125 | |
126 | /* --- Maybe write out a completed triplet --- */ |
127 | |
128 | if (qsz == 2) { |
129 | DPUTC(d, acc & 0xff); |
130 | acc = 0; |
131 | qsz = 0; |
132 | } |
133 | } |
134 | |
135 | ctx->acc = acc; |
136 | ctx->qsz = qsz; |
137 | } else { |
138 | if (ctx->qsz) |
139 | DPUTC(d, ctx->acc << 4); |
140 | } |
141 | } |
142 | |
143 | /* --- @hex_init@ --- * |
144 | * |
145 | * Arguments: @hex_ctx *ctx@ = pointer to context block to initialize |
146 | * |
147 | * Returns: --- |
148 | * |
149 | * Use: Initializes a hex context properly. |
150 | */ |
151 | |
152 | void hex_init(hex_ctx *ctx) |
153 | { |
154 | ctx->acc = 0; |
155 | ctx->qsz = 0; |
156 | ctx->lnlen = 0; |
157 | ctx->indent = "\n"; |
158 | ctx->maxline = 72; |
159 | } |
160 | |
161 | /*----- Test driver code --------------------------------------------------*/ |
162 | |
163 | #ifdef TEST_RIG |
164 | |
165 | int main(int argc, char *argv[]) |
166 | { |
167 | unsigned char buf[BUFSIZ]; |
168 | dstr d = DSTR_INIT; |
169 | hex_ctx ctx; |
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170 | void (*proc)(hex_ctx *, const void *, size_t, dstr *); |
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171 | size_t sz; |
172 | |
173 | hex_init(&ctx); |
174 | |
175 | if (argc > 1 && strcmp(argv[1], "-d") == 0) |
176 | proc = hex_decode; |
177 | else { |
178 | proc = hex_encode; |
179 | putchar('\t'); |
180 | ctx.indent = "\n\t"; |
181 | ctx.maxline = 64; |
182 | } |
183 | |
184 | do { |
185 | sz = fread(buf, 1, sizeof(buf), stdin); |
186 | if (sz) { |
187 | proc(&ctx, buf, sz, &d); |
188 | dstr_write(&d, stdout); |
189 | dstr_destroy(&d); |
190 | } |
191 | } while (sz == sizeof(buf)); |
192 | |
193 | proc(&ctx, 0, 0, &d); |
194 | dstr_write(&d, stdout); |
195 | |
196 | if (proc == hex_encode) |
197 | putchar('\n'); |
198 | |
199 | return (0); |
200 | } |
201 | |
202 | #endif |
203 | |
204 | /*----- That's all, folks -------------------------------------------------*/ |