lib/circbuf.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * (C) Copyright 2003
   4  * Gerry Hamel, geh@ti.com, Texas Instruments
   5  */
   6
   7 #include <log.h>
   8 #include <malloc.h>
   9
  10 #include <circbuf.h>
  11
  12 int buf_init (circbuf_t * buf, unsigned int size)
  13 {
  14         assert (buf != NULL);
  15
  16         buf->size = 0;
  17         buf->totalsize = size;
  18         buf->data = (char *) malloc (sizeof (char) * size);
  19         assert (buf->data != NULL);
  20
  21         buf->top = buf->data;
  22         buf->tail = buf->data;
  23         buf->end = &(buf->data[size]);
  24
  25         return 1;
  26 }
  27
  28 int buf_free (circbuf_t * buf)
  29 {
  30         assert (buf != NULL);
  31         assert (buf->data != NULL);
  32
  33         free (buf->data);
  34         memset (buf, 0, sizeof (circbuf_t));
  35
  36         return 1;
  37 }
  38
  39 int buf_pop (circbuf_t * buf, char *dest, unsigned int len)
  40 {
  41         unsigned int i;
  42         char *p;
  43
  44         assert (buf != NULL);
  45         assert (dest != NULL);
  46
  47         p = buf->top;
  48
  49         /* Cap to number of bytes in buffer */
  50         if (len > buf->size)
  51                 len = buf->size;
  52
  53         for (i = 0; i < len; i++) {
  54                 dest[i] = *p++;
  55                 /* Bounds check. */
  56                 if (p == buf->end) {
  57                         p = buf->data;
  58                 }
  59         }
  60
  61         /* Update 'top' pointer */
  62         buf->top = p;
  63         buf->size -= len;
  64
  65         return len;
  66 }
  67
  68 int buf_push (circbuf_t * buf, const char *src, unsigned int len)
  69 {
  70         /* NOTE:  this function allows push to overwrite old data. */
  71         unsigned int i;
  72         char *p;
  73
  74         assert (buf != NULL);
  75         assert (src != NULL);
  76
  77         p = buf->tail;
  78
  79         for (i = 0; i < len; i++) {
  80                 *p++ = src[i];
  81                 if (p == buf->end) {
  82                         p = buf->data;
  83                 }
  84                 /* Make sure pushing too much data just replaces old data */
  85                 if (buf->size < buf->totalsize) {
  86                         buf->size++;
  87                 } else {
  88                         buf->top++;
  89                         if (buf->top == buf->end) {
  90                                 buf->top = buf->data;
  91                         }
  92                 }
  93         }
  94
  95         /* Update 'tail' pointer */
  96         buf->tail = p;
  97
  98         return len;
  99 }