chiark / gitweb /
New hex encoding stuff.
[mLib] / hex.c
CommitLineData
ee393574 1/* -*-c-*-
2 *
3 * $Id: hex.c,v 1.1 2002/01/13 13:26:30 mdw Exp $
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
30/*----- Revision history --------------------------------------------------*
31 *
32 * $Log: hex.c,v $
33 * Revision 1.1 2002/01/13 13:26:30 mdw
34 * New hex encoding stuff.
35 *
36 */
37
38/*----- Header files ------------------------------------------------------*/
39
40#include <stdio.h>
41#include <stdlib.h>
42#include <string.h>
43
44#include "dstr.h"
45#include "hex.h"
46
47/*----- Important tables --------------------------------------------------*/
48
49static const char encodemap[] = { "0123456789abcdef" };
50
51static const signed char decodemap[] = {
52 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x */
53 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 1x */
54 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 2x */
55 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, -1, -1, -1, -1, -1, /* 3x */
56 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 4x */
57 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 5x */
58 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 6x */
59 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 7x */
60 };
61
62/*----- Main code ---------------------------------------------------------*/
63
64/* --- @hex_encode@ --- *
65 *
66 * Arguments: @hex_ctx *ctx@ = pointer to a context block
67 * @const void *p@ = pointer to a source buffer
68 * @size_t sz@ = size of the source buffer
69 * @dstr *d@ = pointer to destination string
70 *
71 * Returns: ---
72 *
73 * Use: Encodes a binary string in hex.
74 */
75
76void hex_encode(hex_ctx *ctx, const void *p, size_t sz, dstr *d)
77{
78 if (p) {
79 const unsigned char *src = p;
80
81 while (sz) {
82 unsigned x = *src++;
83 sz--;
84 DPUTC(d, encodemap[(x >> 4) & 0xf]);
85 DPUTC(d, encodemap[(x >> 0) & 0xf]);
86 ctx->lnlen += 2;
87 if (ctx->maxline && ctx->lnlen >= ctx->maxline) {
88 dstr_puts(d, ctx->indent);
89 ctx->lnlen = 0;
90 }
91 }
92 }
93}
94
95/* --- @hex_decode@ --- *
96 *
97 * Arguments: @hex_ctx *ctx@ = pointer to a context block
98 * @const void *p@ = pointer to a source buffer
99 * @size_t sz@ = size of the source buffer
100 * @dstr *d@ = pointer to destination string
101 *
102 * Returns: ---
103 *
104 * Use: Decodes a binary string in hex. Pass in a null source
105 * pointer when you thing you've finished.
106 */
107
108void hex_decode(hex_ctx *ctx, const void *p, size_t sz, dstr *d)
109{
110 if (p) {
111 unsigned long acc = ctx->acc;
112 unsigned qsz = ctx->qsz;
113 const char *src = p;
114 int ch;
115
116 while (sz) {
117
118 /* --- Get the next character and convert it --- */
119
120 ch = *src++;
121 if (ch >= 128 || ch < 0)
122 ch = -1;
123 else
124 ch = decodemap[ch];
125 sz--;
126 if (ch == -1)
127 continue;
128
129 /* --- Bung it in the accumulator --- */
130
131 acc = (acc << 4) | ch;
132 qsz++;
133
134 /* --- Maybe write out a completed triplet --- */
135
136 if (qsz == 2) {
137 DPUTC(d, acc & 0xff);
138 acc = 0;
139 qsz = 0;
140 }
141 }
142
143 ctx->acc = acc;
144 ctx->qsz = qsz;
145 } else {
146 if (ctx->qsz)
147 DPUTC(d, ctx->acc << 4);
148 }
149}
150
151/* --- @hex_init@ --- *
152 *
153 * Arguments: @hex_ctx *ctx@ = pointer to context block to initialize
154 *
155 * Returns: ---
156 *
157 * Use: Initializes a hex context properly.
158 */
159
160void hex_init(hex_ctx *ctx)
161{
162 ctx->acc = 0;
163 ctx->qsz = 0;
164 ctx->lnlen = 0;
165 ctx->indent = "\n";
166 ctx->maxline = 72;
167}
168
169/*----- Test driver code --------------------------------------------------*/
170
171#ifdef TEST_RIG
172
173int main(int argc, char *argv[])
174{
175 unsigned char buf[BUFSIZ];
176 dstr d = DSTR_INIT;
177 hex_ctx ctx;
178 void (*proc)(hex_ctx *, const unsigned char *, size_t, dstr *);
179 size_t sz;
180
181 hex_init(&ctx);
182
183 if (argc > 1 && strcmp(argv[1], "-d") == 0)
184 proc = hex_decode;
185 else {
186 proc = hex_encode;
187 putchar('\t');
188 ctx.indent = "\n\t";
189 ctx.maxline = 64;
190 }
191
192 do {
193 sz = fread(buf, 1, sizeof(buf), stdin);
194 if (sz) {
195 proc(&ctx, buf, sz, &d);
196 dstr_write(&d, stdout);
197 dstr_destroy(&d);
198 }
199 } while (sz == sizeof(buf));
200
201 proc(&ctx, 0, 0, &d);
202 dstr_write(&d, stdout);
203
204 if (proc == hex_encode)
205 putchar('\n');
206
207 return (0);
208}
209
210#endif
211
212/*----- That's all, folks -------------------------------------------------*/