Clarify non constness of src in av_fifo_generic_write()
[libav.git] / libavutil / fifo.c
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 #include "common.h"
23 #include "fifo.h"
24
25 AVFifoBuffer *av_fifo_alloc(unsigned int size)
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
38 void av_fifo_free(AVFifoBuffer *f)
39 {
40 if(f){
41 av_free(f->buffer);
42 av_free(f);
43 }
44 }
45
46 void av_fifo_reset(AVFifoBuffer *f)
47 {
48 f->wptr = f->rptr = f->buffer;
49 f->wndx = f->rndx = 0;
50 }
51
52 int av_fifo_size(AVFifoBuffer *f)
53 {
54 return (uint32_t)(f->wndx - f->rndx);
55 }
56
57 int av_fifo_space(AVFifoBuffer *f)
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
122 /** Discard data from the FIFO. */
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 }