1/*
2 * AC-3 DSP utils
3 * Copyright (c) 2011 Justin Ruggles
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#ifndef AVCODEC_AC3DSP_H
23#define AVCODEC_AC3DSP_H
24
25#include <stdint.h>
26
27/**
28 * Number of mantissa bits written for each bap value.
29 * bap values with fractional bits are set to 0 and are calculated separately.
30 */
31extern const uint16_t ff_ac3_bap_bits[16];
32
33typedef struct AC3DSPContext {
34    /**
35     * Set each encoded exponent in a block to the minimum of itself and the
36     * exponents in the same frequency bin of up to 5 following blocks.
37     * @param exp   pointer to the start of the current block of exponents.
38     *              constraints: align 16
39     * @param num_reuse_blocks  number of blocks that will reuse exponents from the current block.
40     *                          constraints: range 0 to 5
41     * @param nb_coefs  number of frequency coefficients.
42     */
43    void (*ac3_exponent_min)(uint8_t *exp, int num_reuse_blocks, int nb_coefs);
44
45    /**
46     * Calculate the maximum MSB of the absolute value of each element in an
47     * array of int16_t.
48     * @param src input array
49     *            constraints: align 16. values must be in range [-32767,32767]
50     * @param len number of values in the array
51     *            constraints: multiple of 16 greater than 0
52     * @return    a value with the same MSB as max(abs(src[]))
53     */
54    int (*ac3_max_msb_abs_int16)(const int16_t *src, int len);
55
56    /**
57     * Left-shift each value in an array of int16_t by a specified amount.
58     * @param src    input array
59     *               constraints: align 16
60     * @param len    number of values in the array
61     *               constraints: multiple of 32 greater than 0
62     * @param shift  left shift amount
63     *               constraints: range [0,15]
64     */
65    void (*ac3_lshift_int16)(int16_t *src, unsigned int len, unsigned int shift);
66
67    /**
68     * Right-shift each value in an array of int32_t by a specified amount.
69     * @param src    input array
70     *               constraints: align 16
71     * @param len    number of values in the array
72     *               constraints: multiple of 16 greater than 0
73     * @param shift  right shift amount
74     *               constraints: range [0,31]
75     */
76    void (*ac3_rshift_int32)(int32_t *src, unsigned int len, unsigned int shift);
77
78    /**
79     * Convert an array of float in range [-1.0,1.0] to int32_t with range
80     * [-(1<<24),(1<<24)]
81     *
82     * @param dst destination array of int32_t.
83     *            constraints: 16-byte aligned
84     * @param src source array of float.
85     *            constraints: 16-byte aligned
86     * @param len number of elements to convert.
87     *            constraints: multiple of 32 greater than zero
88     */
89    void (*float_to_fixed24)(int32_t *dst, const float *src, unsigned int len);
90
91    /**
92     * Calculate bit allocation pointers.
93     * The SNR is the difference between the masking curve and the signal.  AC-3
94     * uses this value for each frequency bin to allocate bits.  The snroffset
95     * parameter is a global adjustment to the SNR for all bins.
96     *
97     * @param[in]  mask       masking curve
98     * @param[in]  psd        signal power for each frequency bin
99     * @param[in]  start      starting bin location
100     * @param[in]  end        ending bin location
101     * @param[in]  snr_offset SNR adjustment
102     * @param[in]  floor      noise floor
103     * @param[in]  bap_tab    look-up table for bit allocation pointers
104     * @param[out] bap        bit allocation pointers
105     */
106    void (*bit_alloc_calc_bap)(int16_t *mask, int16_t *psd, int start, int end,
107                               int snr_offset, int floor,
108                               const uint8_t *bap_tab, uint8_t *bap);
109
110    /**
111     * Update bap counts using the supplied array of bap.
112     *
113     * @param[out] mant_cnt   bap counts for 1 block
114     * @param[in]  bap        array of bap, pointing to start coef bin
115     * @param[in]  len        number of elements to process
116     */
117    void (*update_bap_counts)(uint16_t mant_cnt[16], uint8_t *bap, int len);
118
119    /**
120     * Calculate the number of bits needed to encode a set of mantissas.
121     *
122     * @param[in] mant_cnt    bap counts for all blocks
123     * @return                mantissa bit count
124     */
125    int (*compute_mantissa_size)(uint16_t mant_cnt[6][16]);
126
127    void (*extract_exponents)(uint8_t *exp, int32_t *coef, int nb_coefs);
128} AC3DSPContext;
129
130void ff_ac3dsp_init    (AC3DSPContext *c, int bit_exact);
131void ff_ac3dsp_init_arm(AC3DSPContext *c, int bit_exact);
132void ff_ac3dsp_init_x86(AC3DSPContext *c, int bit_exact);
133
134#endif /* AVCODEC_AC3DSP_H */
135