path: root/libavcodec/mqcenc.c (plain)
blob: 7c9e1a0df961bdaa3ce08020bb88eeee39c7467b

1	/*
2	* MQ-coder encoder
3	* Copyright (c) 2007 Kamil Nowosad
4	*
5	* This file is part of FFmpeg.
6	*
7	* FFmpeg is free software; you can redistribute it and/or
8	* modify it under the terms of the GNU Lesser General Public
9	* License as published by the Free Software Foundation; either
10	* version 2.1 of the License, or (at your option) any later version.
11	*
12	* FFmpeg is distributed in the hope that it will be useful,
13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15	* Lesser General Public License for more details.
16	*
17	* You should have received a copy of the GNU Lesser General Public
18	* License along with FFmpeg; if not, write to the Free Software
19	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20	*/
21
22	/**
23	* MQ-coder encoder
24	* @file
25	* @author Kamil Nowosad
26	*/
27
28	#include "libavutil/avassert.h"
29	#include "mqc.h"
30
31	static void byteout(MqcState *mqc)
32	{
33	retry:
34	if (*mqc->bp == 0xff){
35	mqc->bp++;
36	*mqc->bp = mqc->c >> 20;
37	mqc->c &= 0xfffff;
38	mqc->ct = 7;
39	} else if ((mqc->c & 0x8000000)){
40	(*mqc->bp)++;
41	mqc->c &= 0x7ffffff;
42	goto retry;
43	} else{
44	mqc->bp++;
45	*mqc->bp = mqc->c >> 19;
46	mqc->c &= 0x7ffff;
47	mqc->ct = 8;
48	}
49	}
50
51	static void renorme(MqcState *mqc)
52	{
53	do{
54	mqc->a += mqc->a;
55	mqc->c += mqc->c;
56	if (!--mqc->ct)
57	byteout(mqc);
58	} while (!(mqc->a & 0x8000));
59	}
60
61	static void setbits(MqcState *mqc)
62	{
63	int tmp = mqc->c + mqc->a;
64	mqc->c |= 0xffff;
65	if (mqc->c >= tmp)
66	mqc->c -= 0x8000;
67	}
68
69	void ff_mqc_initenc(MqcState *mqc, uint8_t *bp)
70	{
71	ff_mqc_init_contexts(mqc);
72	mqc->a = 0x8000;
73	mqc->c = 0;
74	mqc->bp = bp-1;
75	mqc->bpstart = bp;
76	mqc->ct = 12 + (*mqc->bp == 0xff);
77	}
78
79	void ff_mqc_encode(MqcState *mqc, uint8_t *cxstate, int d)
80	{
81	int qe;
82
83	qe = ff_mqc_qe[*cxstate];
84	mqc->a -= qe;
85	if ((*cxstate & 1) == d){
86	if (!(mqc->a & 0x8000)){
87	if (mqc->a < qe)
88	mqc->a = qe;
89	else
90	mqc->c += qe;
91	*cxstate = ff_mqc_nmps[*cxstate];
92	renorme(mqc);
93	} else
94	mqc->c += qe;
95	} else{
96	if (mqc->a < qe)
97	mqc->c += qe;
98	else
99	mqc->a = qe;
100	*cxstate = ff_mqc_nlps[*cxstate];
101	renorme(mqc);
102	}
103	}
104
105	int ff_mqc_length(MqcState *mqc)
106	{
107	return mqc->bp - mqc->bpstart;
108	}
109
110	int ff_mqc_flush(MqcState *mqc)
111	{
112	setbits(mqc);
113	mqc->c = mqc->c << mqc->ct;
114	byteout(mqc);
115	mqc->c = mqc->c << mqc->ct;
116	byteout(mqc);
117	if (*mqc->bp != 0xff)
118	mqc->bp++;
119	return mqc->bp - mqc->bpstart;
120	}
121
122	int ff_mqc_flush_to(MqcState *mqc, uint8_t *dst, int *dst_len)
123	{
124	MqcState mqc2 = *mqc;
125	mqc2.bpstart=
126	mqc2.bp = dst;
127	*mqc2.bp = *mqc->bp;
128	ff_mqc_flush(&mqc2);
129	*dst_len = mqc2.bp - dst;
130	if (mqc->bp < mqc->bpstart) {
131	av_assert1(mqc->bpstart - mqc->bp == 1);
132	av_assert1(*dst_len > 0);
133	av_assert1(mqc->bp[0] == 0 && dst[0] == 0);
134	(*dst_len) --;
135	memmove(dst, dst+1, *dst_len);
136	return mqc->bp - mqc->bpstart + 1 + *dst_len;
137	}
138	return mqc->bp - mqc->bpstart + *dst_len;
139	}
140