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Diffstat (limited to 'share/examples/sound/simple.c')
| -rw-r--r-- | share/examples/sound/simple.c | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/share/examples/sound/simple.c b/share/examples/sound/simple.c new file mode 100644 index 000000000000..e458841f596a --- /dev/null +++ b/share/examples/sound/simple.c @@ -0,0 +1,147 @@ +/* + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright (c) 2024 The FreeBSD Foundation + * Copyright (c) 2025 Goran Mekić + * + * Portions of this software were developed by Christos Margiolis + * <christos@FreeBSD.org> under sponsorship from the FreeBSD Foundation. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include "oss.h" + +/* + * Split input buffer into channels. The input buffer is in interleaved format, + * which means if we have 2 channels (L and R), this is what the buffer of 8 + * samples would contain: L,R,L,R,L,R,L,R. The result of this function is a + * buffer containing: L,L,L,L,R,R,R,R. + */ +static void +to_channels(struct config *config, void *output) +{ + uint8_t *in = config->buf; + uint8_t *out = output; + int i, channel, index, offset, byte; + + /* Iterate over bytes in the input buffer */ + for (byte = 0; byte < config->buffer_info.bytes; + byte += config->sample_size) { + /* + * Get index of a sample in the input buffer measured in + * samples + */ + i = byte / config->sample_size; + + /* Get which channel is being processed */ + channel = i % config->audio_info.max_channels; + + /* Get offset of the sample inside a single channel */ + offset = i / config->audio_info.max_channels; + + /* Get index of a sample in the output buffer */ + index = (channel * config->chsamples + offset) * + config->sample_size; + + /* Copy singe sample from input to output */ + memcpy(out+index, in+byte, config->sample_size); + } +} + +/* + * Convert channels into interleaved format and put into output buffer + */ +static void +to_interleaved(struct config *config, void *input) +{ + uint8_t *out = config->buf; + uint8_t *in = input; + int i, index, offset, channel, byte; + + /* Iterate over bytes in the input buffer */ + for (byte = 0; byte < config->buffer_info.bytes; + byte += config->sample_size) { + /* + * Get index of a sample in the input buffer measured in + * samples + */ + index = byte / config->sample_size; + + /* Get which channel is being processed */ + channel = index / config->chsamples; + + /* Get offset of the sample inside a single channel */ + offset = index % config->chsamples; + + /* Get index of a sample in the output buffer */ + i = (config->audio_info.max_channels * offset + channel) * + config->sample_size; + + /* Copy singe sample from input to output */ + memcpy(out+i, in+byte, config->sample_size); + } +} + +int +main(int argc, char *argv[]) +{ + struct config config = { + .device = "/dev/dsp", + .mode = O_RDWR, + .format = AFMT_S32_NE, + .sample_rate = 48000, + }; + int32_t *channels; + int rc, bytes; + + oss_init(&config); + bytes = config.buffer_info.bytes; + channels = malloc(bytes); + + for (;;) { + if ((rc = read(config.fd, config.buf, bytes)) < bytes) { + warn("Requested %d bytes, but read %d!\n", bytes, rc); + break; + } + /* + * Strictly speaking, we could omit "channels" and operate only + * using config->buf, but this example tries to show the real + * world application usage. The problem is that the buffer is + * in interleaved format, and if you'd like to do any + * processing and/or mixing, it is easier to do that if samples + * are grouped per channel. + */ + to_channels(&config, channels); + to_interleaved(&config, channels); + if ((rc = write(config.fd, config.buf, bytes)) < bytes) { + warn("Requested %d bytes, but wrote %d!\n", bytes, rc); + break; + } + } + + free(channels); + free(config.buf); + close(config.fd); + + return (0); +} |