Libav
fifo.c
Go to the documentation of this file.
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 {
27  AVFifoBuffer *f = av_mallocz(sizeof(AVFifoBuffer));
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 {
64  unsigned int old_size = f->end - f->buffer;
65 
66  if (old_size < new_size) {
67  int len = av_fifo_size(f);
68  AVFifoBuffer *f2 = av_fifo_alloc(new_size);
69 
70  if (!f2)
71  return -1;
72  av_fifo_generic_read(f, f2->buffer, len, NULL);
73  f2->wptr += len;
74  f2->wndx += len;
75  av_free(f->buffer);
76  *f = *f2;
77  av_free(f2);
78  }
79  return 0;
80 }
81 
82 /* src must NOT be const as it can be a context for func that may need
83  * updating (like a pointer or byte counter) */
84 int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size,
85  int (*func)(void *, void *, int))
86 {
87  int total = size;
88  do {
89  int len = FFMIN(f->end - f->wptr, size);
90  if (func) {
91  if (func(src, f->wptr, len) <= 0)
92  break;
93  } else {
94  memcpy(f->wptr, src, len);
95  src = (uint8_t *)src + len;
96  }
97 // Write memory barrier needed for SMP here in theory
98  f->wptr += len;
99  if (f->wptr >= f->end)
100  f->wptr = f->buffer;
101  f->wndx += len;
102  size -= len;
103  } while (size > 0);
104  return total - size;
105 }
106 
107 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size,
108  void (*func)(void *, void *, int))
109 {
110 // Read memory barrier needed for SMP here in theory
111  do {
112  int len = FFMIN(f->end - f->rptr, buf_size);
113  if (func)
114  func(dest, f->rptr, len);
115  else {
116  memcpy(dest, f->rptr, len);
117  dest = (uint8_t *)dest + len;
118  }
119 // memory barrier needed for SMP here in theory
120  av_fifo_drain(f, len);
121  buf_size -= len;
122  } while (buf_size > 0);
123  return 0;
124 }
125 
127 void av_fifo_drain(AVFifoBuffer *f, int size)
128 {
129  f->rptr += size;
130  if (f->rptr >= f->end)
131  f->rptr -= f->end - f->buffer;
132  f->rndx += size;
133 }
134 
135 #ifdef TEST
136 
137 int main(void)
138 {
139  /* create a FIFO buffer */
140  AVFifoBuffer *fifo = av_fifo_alloc(13 * sizeof(int));
141  int i, j, n;
142 
143  /* fill data */
144  for (i = 0; av_fifo_space(fifo) >= sizeof(int); i++)
145  av_fifo_generic_write(fifo, &i, sizeof(int), NULL);
146 
147  /* peek at FIFO */
148  n = av_fifo_size(fifo) / sizeof(int);
149  for (i = -n + 1; i < n; i++) {
150  int *v = (int *)av_fifo_peek2(fifo, i * sizeof(int));
151  printf("%d: %d\n", i, *v);
152  }
153  printf("\n");
154 
155  /* read data */
156  for (i = 0; av_fifo_size(fifo) >= sizeof(int); i++) {
157  av_fifo_generic_read(fifo, &j, sizeof(int), NULL);
158  printf("%d ", j);
159  }
160  printf("\n");
161 
162  av_fifo_free(fifo);
163 
164  return 0;
165 }
166 
167 #endif
void * av_malloc(size_t size)
Allocate a block of size bytes with alignment suitable for all memory accesses (including vectors if ...
Definition: mem.c:62
int size
uint8_t * wptr
Definition: fifo.h:33
uint32_t rndx
Definition: fifo.h:34
int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int(*func)(void *, void *, int))
Feed data from a user-supplied callback to an AVFifoBuffer.
Definition: fifo.c:84
void av_freep(void *arg)
Free a memory block which has been allocated with av_malloc(z)() or av_realloc() and set the pointer ...
Definition: mem.c:198
uint8_t
void av_fifo_free(AVFifoBuffer *f)
Free an AVFifoBuffer.
Definition: fifo.c:38
static uint8_t * av_fifo_peek2(const AVFifoBuffer *f, int offs)
Return a pointer to the data stored in a FIFO buffer at a certain offset.
Definition: fifo.h:121
void av_free(void *ptr)
Free a memory block which has been allocated with av_malloc(z)() or av_realloc(). ...
Definition: mem.c:186
int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void(*func)(void *, void *, int))
Feed data from an AVFifoBuffer to a user-supplied callback.
Definition: fifo.c:107
int main(int argc, char **argv)
Definition: avconv.c:2609
#define FFMIN(a, b)
Definition: common.h:57
uint8_t * end
Definition: fifo.h:33
uint8_t * rptr
Definition: fifo.h:33
NULL
Definition: eval.c:55
int av_fifo_space(AVFifoBuffer *f)
Return the amount of space in bytes in the AVFifoBuffer, that is the amount of data you can write int...
Definition: fifo.c:57
int av_fifo_realloc2(AVFifoBuffer *f, unsigned int new_size)
Resize an AVFifoBuffer.
Definition: fifo.c:62
a very simple circular buffer FIFO implementation
uint8_t * buffer
Definition: fifo.h:32
uint32_t wndx
Definition: fifo.h:34
int av_fifo_size(AVFifoBuffer *f)
Return the amount of data in bytes in the AVFifoBuffer, that is the amount of data you can read from ...
Definition: fifo.c:52
common internal and external API header
AVFifoBuffer * av_fifo_alloc(unsigned int size)
Initialize an AVFifoBuffer.
Definition: fifo.c:25
int len
void av_fifo_reset(AVFifoBuffer *f)
Reset the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied...
Definition: fifo.c:46
void av_fifo_drain(AVFifoBuffer *f, int size)
Discard data from the FIFO.
Definition: fifo.c:127
void * av_mallocz(size_t size)
Allocate a block of size bytes with alignment suitable for all memory accesses (including vectors if ...
Definition: mem.c:205