git.distorted.org.uk Git - u/mdw/catacomb/blob - buf.c

   1 /* -*-c-*-
   2  *
   3  * $Id: buf.c,v 1.2 2003/11/10 22:18:30 mdw Exp $
   4  *
   5  * Buffer handling
   6  *
   7  * (c) 2001 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb 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  * Catacomb 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 Catacomb; 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: buf.c,v $
  33  * Revision 1.2  2003/11/10 22:18:30  mdw
  34  * Build fixes.
  35  *
  36  * Revision 1.1  2003/10/11 21:02:33  mdw
  37  * Import buf stuff from tripe.
  38  *
  39  * Revision 1.4  2001/06/19 22:09:54  mdw
  40  * Expose interface, for use in the proxy.
  41  *
  42  * Revision 1.3  2001/03/03 12:06:48  mdw
  43  * Use 16-bit lengths on MPs, since there's a packet limit of 64K anyway.
  44  *
  45  * Revision 1.2  2001/02/16 21:23:20  mdw
  46  * Various minor changes.  Check that MPs are in canonical form when
  47  * loading.
  48  *
  49  * Revision 1.1  2001/02/03 20:26:37  mdw
  50  * Initial checkin.
  51  *
  52  */
  53
  54 /*----- Header files ------------------------------------------------------*/
  55
  56 #include <string.h>
  57
  58 #include "mp.h"
  59 #include "buf.h"
  60
  61 /*----- Main code ---------------------------------------------------------*/
  62
  63 /* --- @buf_init@ --- *
  64  *
  65  * Arguments:   @buf *b@ = pointer to a buffer block
  66  *              @void *p@ = pointer to a buffer
  67  *              @size_t sz@ = size of the buffer
  68  *
  69  * Returns:     ---
  70  *
  71  * Use:         Initializes the buffer block appropriately.
  72  */
  73
  74 void buf_init(buf *b, void *p, size_t sz)
  75 {
  76   b->base = b->p = p;
  77   b->limit = b->p + sz;
  78   b->f = 0;
  79 }
  80
  81 /* --- @buf_break@ --- *
  82  *
  83  * Arguments:   @buf *b@ = pointer to a buffer block
  84  *
  85  * Returns:     Some negative value.
  86  *
  87  * Use:         Marks a buffer as broken.
  88  */
  89
  90 int buf_break(buf *b) { b->f |= BF_BROKEN; return (-1); }
  91
  92 /* --- @buf_flip@ --- *
  93  *
  94  * Arguments:   @buf *b@ = pointer to a buffer block
  95  *
  96  * Returns:     ---
  97  *
  98  * Use:         Flips a buffer so that if you've just been writing to it,
  99  *              you can now read from the bit you've written.
 100  */
 101
 102 void buf_flip(buf *b)
 103 {
 104   b->limit = b->p;
 105   b->p = b->base;
 106 }
 107
 108 /* --- @buf_ensure@ --- *
 109  *
 110  * Arguments:   @buf *b@ = pointer to a buffer block
 111  *              @size_t sz@ = size of data wanted
 112  *
 113  * Returns:     Zero if it worked, nonzero if there wasn't enough space.
 114  *
 115  * Use:         Ensures that there are @sz@ bytes still in the buffer.
 116  */
 117
 118 int buf_ensure(buf *b, size_t sz) { return (BENSURE(b, sz)); }
 119
 120 /* --- @buf_get@ --- *
 121  *
 122  * Arguments:   @buf *b@ = pointer to a buffer block
 123  *              @size_t sz@ = size of the buffer
 124  *
 125  * Returns:     Pointer to the place in the buffer.
 126  *
 127  * Use:         Reserves a space in the buffer of the requested size, and
 128  *              returns its start address.
 129  */
 130
 131 void *buf_get(buf *b, size_t sz)
 132 {
 133   void *p;
 134   if (BENSURE(b, sz))
 135     return (0);
 136   p = BCUR(b);
 137   BSTEP(b, sz);
 138   return (p);
 139 }
 140
 141 /* --- @buf_put@ --- *
 142  *
 143  * Arguments:   @buf *b@ = pointer to a buffer block
 144  *              @const void *p@ = pointer to a buffer
 145  *              @size_t sz@ = size of the buffer
 146  *
 147  * Returns:     Zero if it worked, nonzero if there wasn't enough space.
 148  *
 149  * Use:         Fetches data from some place and puts it in the buffer
 150  */
 151
 152 int buf_put(buf *b, const void *p, size_t sz)
 153 {
 154   if (BENSURE(b, sz))
 155     return (-1);
 156   memcpy(BCUR(b), p, sz);
 157   BSTEP(b, sz);
 158   return (0);
 159 }
 160
 161 /* --- @buf_getbyte@ --- *
 162  *
 163  * Arguments:   @buf *b@ = pointer to a buffer block
 164  *
 165  * Returns:     A byte, or less than zero if there wasn't a byte there.
 166  *
 167  * Use:         Gets a single byte from a buffer.
 168  */
 169
 170 int buf_getbyte(buf *b)
 171 {
 172   if (BENSURE(b, 1))
 173     return (-1);
 174   return (*b->p++);
 175 }
 176
 177 /* --- @buf_putbyte@ --- *
 178  *
 179  * Arguments:   @buf *b@ = pointer to a buffer block
 180  *              @int ch@ = byte to write
 181  *
 182  * Returns:     Zero if OK, nonzero if there wasn't enough space.
 183  *
 184  * Use:         Puts a single byte in a buffer.
 185  */
 186
 187 int buf_putbyte(buf *b, int ch)
 188 {
 189   if (BENSURE(b, 1))
 190     return (-1);
 191   *b->p++ = ch;
 192   return (0);
 193 }
 194
 195 /* --- @buf_getu16@ --- *
 196  *
 197  * Arguments:   @buf *b@ = pointer to a buffer block
 198  *              @uint16 *w@ = where to put the word
 199  *
 200  * Returns:     Zero if OK, or nonzero if there wasn't a word there.
 201  *
 202  * Use:         Gets a 16-bit word from a buffer.
 203  */
 204
 205 int buf_getu16(buf *b, uint16 *w)
 206 {
 207   if (BENSURE(b, 2))
 208     return (-1);
 209   *w = LOAD16(b->p);
 210   BSTEP(b, 2);
 211   return (0);
 212 }
 213
 214 /* --- @buf_putu16@ --- *
 215  *
 216  * Arguments:   @buf *b@ = pointer to a buffer block
 217  *              @uint16 w@ = word to write
 218  *
 219  * Returns:     Zero if OK, nonzero if there wasn't enough space.
 220  *
 221  * Use:         Puts a 16-but word in a buffer.
 222  */
 223
 224 int buf_putu16(buf *b, uint16 w)
 225 {
 226   if (BENSURE(b, 2))
 227     return (-1);
 228   STORE16(b->p, w);
 229   BSTEP(b, 2);
 230   return (0);
 231 }
 232
 233 /* --- @buf_getu32@ --- *
 234  *
 235  * Arguments:   @buf *b@ = pointer to a buffer block
 236  *              @uint32 *w@ = where to put the word
 237  *
 238  * Returns:     Zero if OK, or nonzero if there wasn't a word there.
 239  *
 240  * Use:         Gets a 32-bit word from a buffer.
 241  */
 242
 243 int buf_getu32(buf *b, uint32 *w)
 244 {
 245   if (BENSURE(b, 4))
 246     return (-1);
 247   *w = LOAD32(b->p);
 248   BSTEP(b, 4);
 249   return (0);
 250 }
 251
 252 /* --- @buf_putu32@ --- *
 253  *
 254  * Arguments:   @buf *b@ = pointer to a buffer block
 255  *              @uint32 w@ = word to write
 256  *
 257  * Returns:     Zero if OK, nonzero if there wasn't enough space.
 258  *
 259  * Use:         Puts a 32-but word in a buffer.
 260  */
 261
 262 int buf_putu32(buf *b, uint32 w)
 263 {
 264   if (BENSURE(b, 4))
 265     return (-1);
 266   STORE32(b->p, w);
 267   BSTEP(b, 4);
 268   return (0);
 269 }
 270
 271 /* --- @buf_getmp@ --- *
 272  *
 273  * Arguments:   @buf *b@ = pointer to a buffer block
 274  *
 275  * Returns:     A multiprecision integer, or null if there wasn't one there.
 276  *
 277  * Use:         Gets a multiprecision integer from a buffer.
 278  */
 279
 280 mp *buf_getmp(buf *b)
 281 {
 282   uint16 sz;
 283   mp *m;
 284   if (buf_getu16(b, &sz) || buf_ensure(b, sz))
 285     return (0);
 286   m = mp_loadb(MP_NEW, BCUR(b), sz);
 287   if (mp_octets(m) != sz) {
 288     mp_drop(m);
 289     return (0);
 290   }
 291   BSTEP(b, sz);
 292   return (m);
 293 }
 294
 295 /* --- @buf_putmp@ --- *
 296  *
 297  * Arguments:   @buf *b@ = pointer to a buffer block
 298  *              @mp *m@ = a multiprecision integer
 299  *
 300  * Returns:     Zero if it worked, nonzero if there wasn't enough space.
 301  *
 302  * Use:         Puts a multiprecision integer to a buffer.
 303  */
 304
 305 int buf_putmp(buf *b, mp *m)
 306 {
 307   size_t sz = mp_octets(m);
 308   assert(sz < MASK16);
 309   if (buf_putu16(b, sz) || buf_ensure(b, sz))
 310     return (-1);
 311   mp_storeb(m, BCUR(b), sz);
 312   BSTEP(b, sz);
 313   return (0);
 314 }
 315
 316 /*----- That's all, folks -------------------------------------------------*/