FFmpeg  2.1.1
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 FFmpeg.
7  *
8  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include "avassert.h"
24 #include "common.h"
25 #include "fifo.h"
26 
28 {
29  AVFifoBuffer *f = av_mallocz(sizeof(AVFifoBuffer));
30  if (!f)
31  return NULL;
32  f->buffer = av_malloc(size);
33  f->end = f->buffer + size;
34  av_fifo_reset(f);
35  if (!f->buffer)
36  av_freep(&f);
37  return f;
38 }
39 
41 {
42  if (f) {
43  av_freep(&f->buffer);
44  av_free(f);
45  }
46 }
47 
49 {
50  f->wptr = f->rptr = f->buffer;
51  f->wndx = f->rndx = 0;
52 }
53 
55 {
56  return (uint32_t)(f->wndx - f->rndx);
57 }
58 
60 {
61  return f->end - f->buffer - av_fifo_size(f);
62 }
63 
64 int av_fifo_realloc2(AVFifoBuffer *f, unsigned int new_size)
65 {
66  unsigned int old_size = f->end - f->buffer;
67 
68  if (old_size < new_size) {
69  int len = av_fifo_size(f);
70  AVFifoBuffer *f2 = av_fifo_alloc(new_size);
71 
72  if (!f2)
73  return AVERROR(ENOMEM);
74  av_fifo_generic_read(f, f2->buffer, len, NULL);
75  f2->wptr += len;
76  f2->wndx += len;
77  av_free(f->buffer);
78  *f = *f2;
79  av_free(f2);
80  }
81  return 0;
82 }
83 
84 int av_fifo_grow(AVFifoBuffer *f, unsigned int size)
85 {
86  unsigned int old_size = f->end - f->buffer;
87  if(size + (unsigned)av_fifo_size(f) < size)
88  return AVERROR(EINVAL);
89 
90  size += av_fifo_size(f);
91 
92  if (old_size < size)
93  return av_fifo_realloc2(f, FFMAX(size, 2*size));
94  return 0;
95 }
96 
97 /* src must NOT be const as it can be a context for func that may need
98  * updating (like a pointer or byte counter) */
100  int (*func)(void *, void *, int))
101 {
102  int total = size;
103  uint32_t wndx= f->wndx;
104  uint8_t *wptr= f->wptr;
105 
106  do {
107  int len = FFMIN(f->end - wptr, size);
108  if (func) {
109  if (func(src, wptr, len) <= 0)
110  break;
111  } else {
112  memcpy(wptr, src, len);
113  src = (uint8_t *)src + len;
114  }
115 // Write memory barrier needed for SMP here in theory
116  wptr += len;
117  if (wptr >= f->end)
118  wptr = f->buffer;
119  wndx += len;
120  size -= len;
121  } while (size > 0);
122  f->wndx= wndx;
123  f->wptr= wptr;
124  return total - size;
125 }
126 
127 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size,
128  void (*func)(void *, void *, int))
129 {
130 // Read memory barrier needed for SMP here in theory
131  do {
132  int len = FFMIN(f->end - f->rptr, buf_size);
133  if (func)
134  func(dest, f->rptr, len);
135  else {
136  memcpy(dest, f->rptr, len);
137  dest = (uint8_t *)dest + len;
138  }
139 // memory barrier needed for SMP here in theory
140  av_fifo_drain(f, len);
141  buf_size -= len;
142  } while (buf_size > 0);
143  return 0;
144 }
145 
146 /** Discard data from the FIFO. */
147 void av_fifo_drain(AVFifoBuffer *f, int size)
148 {
149  av_assert2(av_fifo_size(f) >= size);
150  f->rptr += size;
151  if (f->rptr >= f->end)
152  f->rptr -= f->end - f->buffer;
153  f->rndx += size;
154 }
155 
156 #ifdef TEST
157 
158 int main(void)
159 {
160  /* create a FIFO buffer */
161  AVFifoBuffer *fifo = av_fifo_alloc(13 * sizeof(int));
162  int i, j, n;
163 
164  /* fill data */
165  for (i = 0; av_fifo_space(fifo) >= sizeof(int); i++)
166  av_fifo_generic_write(fifo, &i, sizeof(int), NULL);
167 
168  /* peek at FIFO */
169  n = av_fifo_size(fifo) / sizeof(int);
170  for (i = -n + 1; i < n; i++) {
171  int *v = (int *)av_fifo_peek2(fifo, i * sizeof(int));
172  printf("%d: %d\n", i, *v);
173  }
174  printf("\n");
175 
176  /* read data */
177  for (i = 0; av_fifo_size(fifo) >= sizeof(int); i++) {
178  av_fifo_generic_read(fifo, &j, sizeof(int), NULL);
179  printf("%d ", j);
180  }
181  printf("\n");
182 
183  av_fifo_free(fifo);
184 
185  return 0;
186 }
187 
188 #endif
float v
int size
uint8_t * wptr
Definition: fifo.h:33
uint8_t * rptr
Definition: fifo.h:33
uint32_t rndx
Definition: fifo.h:34
void av_freep(void *ptr)
Free a memory block which has been allocated with av_malloc(z)() or av_realloc() and set the pointer ...
Definition: mem.c:234
simple assert() macros that are a bit more flexible than ISO C assert().
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:54
uint8_t * buffer
Definition: fifo.h:32
uint8_t
void av_fifo_free(AVFifoBuffer *f)
Free an AVFifoBuffer.
Definition: fifo.c:40
a very simple circular buffer FIFO implementation
void av_fifo_drain(AVFifoBuffer *f, int size)
Read and discard the specified amount of data from an AVFifoBuffer.
Definition: fifo.c:147
void av_free(void *ptr)
Free a memory block which has been allocated with av_malloc(z)() or av_realloc(). ...
Definition: mem.c:219
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:99
int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size)
Resize an AVFifoBuffer.
Definition: fifo.c:64
uint8_t * end
Definition: fifo.h:33
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:134
void * av_malloc(size_t size) av_malloc_attrib 1(1)
Allocate a block of size bytes with alignment suitable for all memory accesses (including vectors if ...
Definition: mem.c:73
#define FFMIN(a, b)
Definition: avcodec.h:925
int n
Definition: avisynth_c.h:588
AVS_Value src
Definition: avisynth_c.h:523
#define FFMAX(a, b)
Definition: avcodec.h:923
AVFifoBuffer * av_fifo_alloc(unsigned int size)
Initialize an AVFifoBuffer.
Definition: fifo.c:27
int(* func)(AVBPrint *dst, const char *in, const char *arg)
Definition: jacosubdec.c:70
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:127
int av_fifo_grow(AVFifoBuffer *f, unsigned int additional_space)
Enlarge an AVFifoBuffer.
Definition: fifo.c:84
uint32_t wndx
Definition: fifo.h:34
int len
#define AVERROR(e)
int main(int argc, char **argv)
Definition: main.c:22
common internal and external API header
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:59
void * av_mallocz(size_t size) av_malloc_attrib 1(1)
Allocate a block of size bytes with alignment suitable for all memory accesses (including vectors if ...
Definition: mem.c:241
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:48
#define av_assert2(cond)
assert() equivalent, that does lie in speed critical code.
Definition: avassert.h:63