path: root/libavutil/fifo.c (plain)
blob: 1060aedf135182befc3c7c6df51e50b56304c443

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
27	static AVFifoBuffer *fifo_alloc_common(void *buffer, size_t size)
28	{
29	AVFifoBuffer *f;
30	if (!buffer)
31	return NULL;
32	f = av_mallocz(sizeof(AVFifoBuffer));
33	if (!f) {
34	av_free(buffer);
35	return NULL;
36	}
37	f->buffer = buffer;
38	f->end = f->buffer + size;
39	av_fifo_reset(f);
40	return f;
41	}
42
43	AVFifoBuffer *av_fifo_alloc(unsigned int size)
44	{
45	void *buffer = av_malloc(size);
46	return fifo_alloc_common(buffer, size);
47	}
48
49	AVFifoBuffer *av_fifo_alloc_array(size_t nmemb, size_t size)
50	{
51	void *buffer = av_malloc_array(nmemb, size);
52	return fifo_alloc_common(buffer, nmemb * size);
53	}
54
55	void av_fifo_free(AVFifoBuffer *f)
56	{
57	if (f) {
58	av_freep(&f->buffer);
59	av_free(f);
60	}
61	}
62
63	void av_fifo_freep(AVFifoBuffer **f)
64	{
65	if (f) {
66	av_fifo_free(*f);
67	*f = NULL;
68	}
69	}
70
71	void av_fifo_reset(AVFifoBuffer *f)
72	{
73	f->wptr = f->rptr = f->buffer;
74	f->wndx = f->rndx = 0;
75	}
76
77	int av_fifo_size(const AVFifoBuffer *f)
78	{
79	return (uint32_t)(f->wndx - f->rndx);
80	}
81
82	int av_fifo_space(const AVFifoBuffer *f)
83	{
84	return f->end - f->buffer - av_fifo_size(f);
85	}
86
87	int av_fifo_realloc2(AVFifoBuffer *f, unsigned int new_size)
88	{
89	unsigned int old_size = f->end - f->buffer;
90
91	if (old_size < new_size) {
92	int len = av_fifo_size(f);
93	AVFifoBuffer *f2 = av_fifo_alloc(new_size);
94
95	if (!f2)
96	return AVERROR(ENOMEM);
97	av_fifo_generic_read(f, f2->buffer, len, NULL);
98	f2->wptr += len;
99	f2->wndx += len;
100	av_free(f->buffer);
101	*f = *f2;
102	av_free(f2);
103	}
104	return 0;
105	}
106
107	int av_fifo_grow(AVFifoBuffer *f, unsigned int size)
108	{
109	unsigned int old_size = f->end - f->buffer;
110	if(size + (unsigned)av_fifo_size(f) < size)
111	return AVERROR(EINVAL);
112
113	size += av_fifo_size(f);
114
115	if (old_size < size)
116	return av_fifo_realloc2(f, FFMAX(size, 2*old_size));
117	return 0;
118	}
119
120	/* src must NOT be const as it can be a context for func that may need
121	* updating (like a pointer or byte counter) */
122	int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size,
123	int (*func)(void *, void *, int))
124	{
125	int total = size;
126	uint32_t wndx= f->wndx;
127	uint8_t *wptr= f->wptr;
128
129	do {
130	int len = FFMIN(f->end - wptr, size);
131	if (func) {
132	len = func(src, wptr, len);
133	if (len <= 0)
134	break;
135	} else {
136	memcpy(wptr, src, len);
137	src = (uint8_t *)src + len;
138	}
139	// Write memory barrier needed for SMP here in theory
140	wptr += len;
141	if (wptr >= f->end)
142	wptr = f->buffer;
143	wndx += len;
144	size -= len;
145	} while (size > 0);
146	f->wndx= wndx;
147	f->wptr= wptr;
148	return total - size;
149	}
150
151	int av_fifo_generic_peek_at(AVFifoBuffer *f, void *dest, int offset, int buf_size, void (*func)(void*, void*, int))
152	{
153	uint8_t *rptr = f->rptr;
154
155	av_assert2(offset >= 0);
156
157	/*
158	* *ndx are indexes modulo 2^32, they are intended to overflow,
159	* to handle *ndx greater than 4gb.
160	*/
161	av_assert2(buf_size + (unsigned)offset <= f->wndx - f->rndx);
162
163	if (offset >= f->end - rptr)
164	rptr += offset - (f->end - f->buffer);
165	else
166	rptr += offset;
167
168	while (buf_size > 0) {
169	int len;
170
171	if (rptr >= f->end)
172	rptr -= f->end - f->buffer;
173
174	len = FFMIN(f->end - rptr, buf_size);
175	if (func)
176	func(dest, rptr, len);
177	else {
178	memcpy(dest, rptr, len);
179	dest = (uint8_t *)dest + len;
180	}
181
182	buf_size -= len;
183	rptr += len;
184	}
185
186	return 0;
187	}
188
189	int av_fifo_generic_peek(AVFifoBuffer *f, void *dest, int buf_size,
190	void (*func)(void *, void *, int))
191	{
192	// Read memory barrier needed for SMP here in theory
193	uint8_t *rptr = f->rptr;
194
195	do {
196	int len = FFMIN(f->end - rptr, buf_size);
197	if (func)
198	func(dest, rptr, len);
199	else {
200	memcpy(dest, rptr, len);
201	dest = (uint8_t *)dest + len;
202	}
203	// memory barrier needed for SMP here in theory
204	rptr += len;
205	if (rptr >= f->end)
206	rptr -= f->end - f->buffer;
207	buf_size -= len;
208	} while (buf_size > 0);
209
210	return 0;
211	}
212
213	int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size,
214	void (*func)(void *, void *, int))
215	{
216	// Read memory barrier needed for SMP here in theory
217	do {
218	int len = FFMIN(f->end - f->rptr, buf_size);
219	if (func)
220	func(dest, f->rptr, len);
221	else {
222	memcpy(dest, f->rptr, len);
223	dest = (uint8_t *)dest + len;
224	}
225	// memory barrier needed for SMP here in theory
226	av_fifo_drain(f, len);
227	buf_size -= len;
228	} while (buf_size > 0);
229	return 0;
230	}
231
232	/** Discard data from the FIFO. */
233	void av_fifo_drain(AVFifoBuffer *f, int size)
234	{
235	av_assert2(av_fifo_size(f) >= size);
236	f->rptr += size;
237	if (f->rptr >= f->end)
238	f->rptr -= f->end - f->buffer;
239	f->rndx += size;
240	}
241