1/***
2  This file is part of PulseAudio.
3
4  Copyright 2004-2006 Lennart Poettering
5
6  PulseAudio is free software; you can redistribute it and/or modify
7  it under the terms of the GNU Lesser General Public License as published
8  by the Free Software Foundation; either version 2.1 of the License,
9  or (at your option) any later version.
10
11  PulseAudio is distributed in the hope that it will be useful, but
12  WITHOUT ANY WARRANTY; without even the implied warranty of
13  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  General Public License for more details.
15
16  You should have received a copy of the GNU Lesser General Public License
17  along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
18***/
19
20#ifdef HAVE_CONFIG_H
21#include <config.h>
22#endif
23
24#include <pulse/xmalloc.h>
25
26#include <pulsecore/resampler.h>
27
28struct trivial_data { /* data specific to the trivial resampler */
29    unsigned o_counter;
30    unsigned i_counter;
31};
32
33static unsigned trivial_resample(pa_resampler *r, const pa_memchunk *input, unsigned in_n_frames, pa_memchunk *output, unsigned *out_n_frames) {
34    unsigned i_index, o_index;
35    void *src, *dst;
36    struct trivial_data *trivial_data;
37
38    pa_assert(r);
39    pa_assert(input);
40    pa_assert(output);
41    pa_assert(out_n_frames);
42
43    trivial_data = r->impl.data;
44
45    src = pa_memblock_acquire_chunk(input);
46    dst = pa_memblock_acquire_chunk(output);
47
48    for (o_index = 0;; o_index++, trivial_data->o_counter++) {
49        i_index = ((uint64_t) trivial_data->o_counter * r->i_ss.rate) / r->o_ss.rate;
50        i_index = i_index > trivial_data->i_counter ? i_index - trivial_data->i_counter : 0;
51
52        if (i_index >= in_n_frames)
53            break;
54
55        pa_assert_fp(o_index * r->w_fz < pa_memblock_get_length(output->memblock));
56
57        memcpy((uint8_t*) dst + r->w_fz * o_index, (uint8_t*) src + r->w_fz * i_index, (int) r->w_fz);
58    }
59
60    pa_memblock_release(input->memblock);
61    pa_memblock_release(output->memblock);
62
63    *out_n_frames = o_index;
64
65    trivial_data->i_counter += in_n_frames;
66
67    /* Normalize counters */
68    while (trivial_data->i_counter >= r->i_ss.rate) {
69        pa_assert(trivial_data->o_counter >= r->o_ss.rate);
70
71        trivial_data->i_counter -= r->i_ss.rate;
72        trivial_data->o_counter -= r->o_ss.rate;
73    }
74
75    return 0;
76}
77
78static void trivial_update_rates_or_reset(pa_resampler *r) {
79    struct trivial_data *trivial_data;
80    pa_assert(r);
81
82    trivial_data = r->impl.data;
83
84    trivial_data->i_counter = 0;
85    trivial_data->o_counter = 0;
86}
87
88int pa_resampler_trivial_init(pa_resampler *r) {
89    struct trivial_data *trivial_data;
90    pa_assert(r);
91
92    trivial_data = pa_xnew0(struct trivial_data, 1);
93
94    r->impl.resample = trivial_resample;
95    r->impl.update_rates = trivial_update_rates_or_reset;
96    r->impl.reset = trivial_update_rates_or_reset;
97    r->impl.data = trivial_data;
98
99    return 0;
100}
101