xref: /third_party/ffmpeg/libavcodec/jpegls.h (revision cabdff1a) 
1/*
2 * JPEG-LS common code
3 * Copyright (c) 2003 Michael Niedermayer
4 * Copyright (c) 2006 Konstantin Shishkov
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/**
24 * @file
25 * JPEG-LS common code.
26 */
27
28#ifndef AVCODEC_JPEGLS_H
29#define AVCODEC_JPEGLS_H
30
31#include <limits.h>
32#include "libavutil/common.h"
33
34#undef near /* This file uses struct member 'near' which in windows.h is defined as empty. */
35
36typedef struct JLSState {
37    int T1, T2, T3;
38    int A[367], B[367], C[365], N[367];
39    int limit, reset, bpp, qbpp, maxval, range;
40    int near, twonear;
41    int run_index[4];
42} JLSState;
43
44/**
45 * Calculate initial JPEG-LS parameters
46 */
47void ff_jpegls_init_state(JLSState *state);
48
49/**
50 * Calculate quantized gradient value, used for context determination
51 */
52static inline int ff_jpegls_quantize(JLSState *s, int v)
53{
54    if (v == 0)
55        return 0;
56    if (v < 0) {
57        if (v <= -s->T3)
58            return -4;
59        if (v <= -s->T2)
60            return -3;
61        if (v <= -s->T1)
62            return -2;
63        if (v < -s->near)
64            return -1;
65        return 0;
66    } else {
67        if (v <= s->near)
68            return 0;
69        if (v < s->T1)
70            return 1;
71        if (v < s->T2)
72            return 2;
73        if (v < s->T3)
74            return 3;
75        return 4;
76    }
77}
78
79/**
80 * Calculate JPEG-LS codec values
81 */
82void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all);
83
84static inline void ff_jpegls_downscale_state(JLSState *state, int Q)
85{
86    if (state->N[Q] == state->reset) {
87        state->A[Q] >>= 1;
88        state->B[Q] >>= 1;
89        state->N[Q] >>= 1;
90    }
91    state->N[Q]++;
92}
93
94static inline int ff_jpegls_update_state_regular(JLSState *state,
95                                                 int Q, int err)
96{
97    if(FFABS(err) > 0xFFFF || FFABS(err) > INT_MAX - state->A[Q])
98        return -0x10000;
99    state->A[Q] += FFABS(err);
100    err         *= state->twonear;
101    state->B[Q] += err;
102
103    ff_jpegls_downscale_state(state, Q);
104
105    if (state->B[Q] <= -state->N[Q]) {
106        state->B[Q] = FFMAX(state->B[Q] + state->N[Q], 1 - state->N[Q]);
107        if (state->C[Q] > -128)
108            state->C[Q]--;
109    } else if (state->B[Q] > 0) {
110        state->B[Q] = FFMIN(state->B[Q] - state->N[Q], 0);
111        if (state->C[Q] < 127)
112            state->C[Q]++;
113    }
114
115    return err;
116}
117
118#define R(a, i)    (bits == 8 ?  ((uint8_t *)(a))[i]      :  ((uint16_t *)(a))[i])
119#define W(a, i, v) (bits == 8 ? (((uint8_t *)(a))[i] = v) : (((uint16_t *)(a))[i] = v))
120
121#endif /* AVCODEC_JPEGLS_H */
122