common/circbuf.c

   1 /*
   2  * (C) Copyright 2003
   3  * Gerry Hamel, geh@ti.com, Texas Instruments
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  *
  19  */
  20
  21 #include <common.h>
  22 #include <malloc.h>
  23
  24 #include <circbuf.h>
  25
  26
  27 int buf_init (circbuf_t * buf, unsigned int size)
  28 {
  29         assert (buf != NULL);
  30
  31         buf->size = 0;
  32         buf->totalsize = size;
  33         buf->data = (char *) malloc (sizeof (char) * size);
  34         assert (buf->data != NULL);
  35
  36         buf->top = buf->data;
  37         buf->tail = buf->data;
  38         buf->end = &(buf->data[size]);
  39
  40         return 1;
  41 }
  42
  43 int buf_free (circbuf_t * buf)
  44 {
  45         assert (buf != NULL);
  46         assert (buf->data != NULL);
  47
  48         free (buf->data);
  49         memset (buf, 0, sizeof (circbuf_t));
  50
  51         return 1;
  52 }
  53
  54 int buf_pop (circbuf_t * buf, char *dest, unsigned int len)
  55 {
  56         unsigned int i;
  57         char *p = buf->top;
  58
  59         assert (buf != NULL);
  60         assert (dest != NULL);
  61
  62         /* Cap to number of bytes in buffer */
  63         if (len > buf->size)
  64                 len = buf->size;
  65
  66         for (i = 0; i < len; i++) {
  67                 dest[i] = *p++;
  68                 /* Bounds check. */
  69                 if (p == buf->end) {
  70                         p = buf->data;
  71                 }
  72         }
  73
  74         /* Update 'top' pointer */
  75         buf->top = p;
  76         buf->size -= len;
  77
  78         return len;
  79 }
  80
  81 int buf_push (circbuf_t * buf, const char *src, unsigned int len)
  82 {
  83         /* NOTE:  this function allows push to overwrite old data. */
  84         unsigned int i;
  85         char *p = buf->tail;
  86
  87         assert (buf != NULL);
  88         assert (src != NULL);
  89
  90         for (i = 0; i < len; i++) {
  91                 *p++ = src[i];
  92                 if (p == buf->end) {
  93                         p = buf->data;
  94                 }
  95                 /* Make sure pushing too much data just replaces old data */
  96                 if (buf->size < buf->totalsize) {
  97                         buf->size++;
  98                 } else {
  99                         buf->top++;
 100                         if (buf->top == buf->end) {
 101                                 buf->top = buf->data;
 102                         }
 103                 }
 104         }
 105
 106         /* Update 'tail' pointer */
 107         buf->tail = p;
 108
 109         return len;
 110 }