fifo.c
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1 /*
2  * a very simple circular buffer FIFO implementation
3  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
4  * Copyright (c) 2006 Roman Shaposhnik
5  *
6  * This file is part of Libav.
7  *
8  * Libav is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * Libav is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with Libav; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 #include "common.h"
23 #include "fifo.h"
24 
26 {
28  if(!f)
29  return NULL;
30  f->buffer = av_malloc(size);
31  f->end = f->buffer + size;
32  av_fifo_reset(f);
33  if (!f->buffer)
34  av_freep(&f);
35  return f;
36 }
37 
39 {
40  if(f){
41  av_free(f->buffer);
42  av_free(f);
43  }
44 }
45 
47 {
48  f->wptr = f->rptr = f->buffer;
49  f->wndx = f->rndx = 0;
50 }
51 
53 {
54  return (uint32_t)(f->wndx - f->rndx);
55 }
56 
58 {
59  return f->end - f->buffer - av_fifo_size(f);
60 }
61 
62 int av_fifo_realloc2(AVFifoBuffer *f, unsigned int new_size) {
63  unsigned int old_size= f->end - f->buffer;
64 
65  if(old_size < new_size){
66  int len= av_fifo_size(f);
67  AVFifoBuffer *f2= av_fifo_alloc(new_size);
68 
69  if (!f2)
70  return -1;
71  av_fifo_generic_read(f, f2->buffer, len, NULL);
72  f2->wptr += len;
73  f2->wndx += len;
74  av_free(f->buffer);
75  *f= *f2;
76  av_free(f2);
77  }
78  return 0;
79 }
80 
81 // src must NOT be const as it can be a context for func that may need updating (like a pointer or byte counter)
82 int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int))
83 {
84  int total = size;
85  do {
86  int len = FFMIN(f->end - f->wptr, size);
87  if(func) {
88  if(func(src, f->wptr, len) <= 0)
89  break;
90  } else {
91  memcpy(f->wptr, src, len);
92  src = (uint8_t*)src + len;
93  }
94 // Write memory barrier needed for SMP here in theory
95  f->wptr += len;
96  if (f->wptr >= f->end)
97  f->wptr = f->buffer;
98  f->wndx += len;
99  size -= len;
100  } while (size > 0);
101  return total - size;
102 }
103 
104 
105 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int))
106 {
107 // Read memory barrier needed for SMP here in theory
108  do {
109  int len = FFMIN(f->end - f->rptr, buf_size);
110  if(func) func(dest, f->rptr, len);
111  else{
112  memcpy(dest, f->rptr, len);
113  dest = (uint8_t*)dest + len;
114  }
115 // memory barrier needed for SMP here in theory
116  av_fifo_drain(f, len);
117  buf_size -= len;
118  } while (buf_size > 0);
119  return 0;
120 }
121 
123 void av_fifo_drain(AVFifoBuffer *f, int size)
124 {
125  f->rptr += size;
126  if (f->rptr >= f->end)
127  f->rptr -= f->end - f->buffer;
128  f->rndx += size;
129 }
130 
131 #ifdef TEST
132 
133 #undef printf
134 
135 int main(void)
136 {
137  /* create a FIFO buffer */
138  AVFifoBuffer *fifo = av_fifo_alloc(13 * sizeof(int));
139  int i, j, n;
140 
141  /* fill data */
142  for (i = 0; av_fifo_space(fifo) >= sizeof(int); i++)
143  av_fifo_generic_write(fifo, &i, sizeof(int), NULL);
144 
145  /* peek at FIFO */
146  n = av_fifo_size(fifo)/sizeof(int);
147  for (i = -n+1; i < n; i++) {
148  int *v = (int *)av_fifo_peek2(fifo, i*sizeof(int));
149  printf("%d: %d\n", i, *v);
150  }
151  printf("\n");
152 
153  /* read data */
154  for (i = 0; av_fifo_size(fifo) >= sizeof(int); i++) {
155  av_fifo_generic_read(fifo, &j, sizeof(int), NULL);
156  printf("%d ", j);
157  }
158  printf("\n");
159 
160  av_fifo_free(fifo);
161 
162  return 0;
163 }
164 
165 #endif