sound examples: Simplify audio example

- Merge ossinit.h and basic.c.
- Rename basic.c to audio.c.
- Use err(3) instead of fprintf(3) + exit(3).
- Some style(9) improvements.

Sponsored by:	The FreeBSD Foundation
MFC after:	2 days
Reviewed by:	dev_submerge.ch
Differential Revision:	https://reviews.freebsd.org/D46307

share/examples/Makefile

@@ -320,9 +320,8 @@ SE_SOUND= \
 SE_DIRS+=	sound/oss
 SE_SOUND_OSS= \
 	README \
-	basic.c \
+	audio.c \
-	midi.c \
+	midi.c
-	ossinit.h
 
 SE_DIRS+=	sunrpc
 SE_SUNRPC=	Makefile

share/examples/sound/oss/audio.c

@@ -0,0 +1,310 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2021 Goran Mekić
+ * Copyright (c) 2024 The FreeBSD Foundation
+ *
+ * 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 <sys/soundcard.h>
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#ifndef SAMPLE_SIZE
+#define SAMPLE_SIZE 16
+#endif
+
+/* Format can be unsigned, in which case replace S with U */
+#if SAMPLE_SIZE == 32
+typedef int32_t sample_t;
+int	format = AFMT_S32_NE;		/* Signed 32bit native endian format */
+#elif SAMPLE_SIZE == 16
+typedef int16_t sample_t;
+int	format = AFMT_S16_NE;		/* Signed 16bit native endian format */
+#elif SAMPLE_SIZE == 8
+typedef int8_t sample_t;
+int	format = AFMT_S8_NE;		/* Signed 8bit native endian format */
+#else
+#error Unsupported sample format!
+typedef int32_t sample_t;
+int	format = AFMT_S32_NE;		/* Not a real value, just silencing
+					 * compiler errors */
+#endif
+
+/*
+ * Minimal configuration for OSS
+ * For real world applications, this structure will probably contain many
+ * more fields
+ */
+typedef struct config {
+	char   *device;
+	int	channels;
+	int	fd;
+	int	format;
+	int	frag;
+	int	sample_count;
+	int	sample_rate;
+	int	sample_size;
+	int	chsamples;
+	int	mmap;
+	oss_audioinfo audio_info;
+	audio_buf_info buffer_info;
+} config_t;
+
+/*
+ * Error state is indicated by value=-1 in which case application exits with
+ * error
+ */
+static inline void
+check_error(const int value, const char *message)
+{
+	if (value == -1)
+		err(1, "OSS error: %s\n", message);
+}
+
+
+/* Calculate frag by giving it minimal size of buffer */
+static inline int
+size2frag(int x)
+{
+	int frag = 0;
+
+	while ((1 << frag) < x)
+		++frag;
+
+	return (frag);
+}
+
+/*
+ * Split input buffer into channels. 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 are two channels
+ * containing: L,L,L,L and R,R,R,R.
+ */
+static void
+oss_split(config_t *config, sample_t *input, sample_t *output)
+{
+	int channel, index, i;
+
+	for (i = 0; i < config->sample_count; ++i) {
+		channel = i % config->channels;
+		index = i / config->channels;
+		output[channel * index] = input[i];
+	}
+}
+
+/*
+ * Convert channels into interleaved format and place it in output
+ * buffer
+ */
+static void
+oss_merge(config_t *config, sample_t *input, sample_t *output)
+{
+	int channel, index;
+
+	for (channel = 0; channel < config->channels; ++channel) {
+		for (index = 0; index < config->chsamples; ++index) {
+			output[index * config->channels + channel] =
+			    input[channel * index];
+		}
+	}
+}
+
+static void
+oss_init(config_t *config)
+{
+	int error, tmp, min_frag;
+
+	/* Open the device for read and write */
+	config->fd = open(config->device, O_RDWR);
+	check_error(config->fd, "open");
+
+	/* Get device information */
+	config->audio_info.dev = -1;
+	error = ioctl(config->fd, SNDCTL_ENGINEINFO, &(config->audio_info));
+	check_error(error, "SNDCTL_ENGINEINFO");
+	printf("min_channels: %d\n", config->audio_info.min_channels);
+	printf("max_channels: %d\n", config->audio_info.max_channels);
+	printf("latency: %d\n", config->audio_info.latency);
+	printf("handle: %s\n", config->audio_info.handle);
+	if (config->audio_info.min_rate > config->sample_rate ||
+	    config->sample_rate > config->audio_info.max_rate) {
+		errx(1, "%s doesn't support chosen samplerate of %dHz!\n",
+		    config->device, config->sample_rate);
+	}
+	if (config->channels < 1)
+		config->channels = config->audio_info.max_channels;
+
+	/*
+	 * If device is going to be used in mmap mode, disable all format
+	 * conversions. Official OSS documentation states error code should not
+	 * be checked.
+	 * http://manuals.opensound.com/developer/mmap_test.c.html#LOC10
+         */
+	if (config->mmap) {
+		tmp = 0;
+		ioctl(config->fd, SNDCTL_DSP_COOKEDMODE, &tmp);
+	}
+
+	/*
+	 * Set number of channels. If number of channels is chosen to the value
+	 * near the one wanted, save it in config
+         */
+	tmp = config->channels;
+	error = ioctl(config->fd, SNDCTL_DSP_CHANNELS, &tmp);
+	check_error(error, "SNDCTL_DSP_CHANNELS");
+	/* Or check if tmp is close enough? */
+	if (tmp != config->channels) {
+		errx(1, "%s doesn't support chosen channel count of %d set "
+		    "to %d!\n", config->device, config->channels, tmp);
+	}
+	config->channels = tmp;
+
+	/* Set format, or bit size: 8, 16, 24 or 32 bit sample */
+	tmp = config->format;
+	error = ioctl(config->fd, SNDCTL_DSP_SETFMT, &tmp);
+	check_error(error, "SNDCTL_DSP_SETFMT");
+	if (tmp != config->format) {
+		errx(1, "%s doesn't support chosen sample format!\n",
+		    config->device);
+	}
+
+	/* Most common values for samplerate (in kHz): 44.1, 48, 88.2, 96 */
+	tmp = config->sample_rate;
+	error = ioctl(config->fd, SNDCTL_DSP_SPEED, &tmp);
+	check_error(error, "SNDCTL_DSP_SPEED");
+
+	/* Get and check device capabilities */
+	error = ioctl(config->fd, SNDCTL_DSP_GETCAPS, &(config->audio_info.caps));
+	check_error(error, "SNDCTL_DSP_GETCAPS");
+	if (!(config->audio_info.caps & PCM_CAP_DUPLEX))
+		errx(1, "Device doesn't support full duplex!\n");
+
+	if (config->mmap) {
+		if (!(config->audio_info.caps & PCM_CAP_TRIGGER))
+			errx(1, "Device doesn't support triggering!\n");
+		if (!(config->audio_info.caps & PCM_CAP_MMAP))
+			errx(1, "Device doesn't support mmap mode!\n");
+	}
+
+	/*
+	 * If desired frag is smaller than minimum, based on number of channels
+	 * and format (size in bits: 8, 16, 24, 32), set that as frag. Buffer
+	 * size is 2^frag, but the real size of the buffer will be read when
+	 * the configuration of the device is successful
+         */
+	min_frag = size2frag(config->sample_size * config->channels);
+
+	if (config->frag < min_frag)
+		config->frag = min_frag;
+
+	/*
+	 * Allocate buffer in fragments. Total buffer will be split in number
+	 * of fragments (2 by default)
+         */
+	if (config->buffer_info.fragments < 0)
+		config->buffer_info.fragments = 2;
+	tmp = ((config->buffer_info.fragments) << 16) | config->frag;
+	error = ioctl(config->fd, SNDCTL_DSP_SETFRAGMENT, &tmp);
+	check_error(error, "SNDCTL_DSP_SETFRAGMENT");
+
+	/* When all is set and ready to go, get the size of buffer */
+	error = ioctl(config->fd, SNDCTL_DSP_GETOSPACE, &(config->buffer_info));
+	check_error(error, "SNDCTL_DSP_GETOSPACE");
+	if (config->buffer_info.bytes < 1) {
+		errx(1, "OSS buffer error: buffer size can not be %d\n",
+		    config->buffer_info.bytes);
+	}
+	config->sample_count = config->buffer_info.bytes / config->sample_size;
+	config->chsamples = config->sample_count / config->channels;
+}
+
+int
+main(int argc, char *argv[])
+{
+	int ret, bytes;
+	int8_t *ibuf, *obuf;
+	config_t config = {
+		.device = "/dev/dsp",
+		.channels = -1,
+		.format = format,
+		.frag = -1,
+		.sample_rate = 48000,
+		.sample_size = sizeof(sample_t),
+		.buffer_info.fragments = -1,
+		.mmap = 0,
+	};
+
+	/* Initialize device */
+	oss_init(&config);
+
+	/*
+	 * Allocate input and output buffers so that their size match frag_size
+	 */
+	bytes = config.buffer_info.bytes;
+	ibuf = malloc(bytes);
+	obuf = malloc(bytes);
+	sample_t *channels = malloc(bytes);
+
+	printf("bytes: %d, fragments: %d, fragsize: %d, fragstotal: %d, "
+	    "samples: %d\n",
+	    bytes, config.buffer_info.fragments,
+	    config.buffer_info.fragsize, config.buffer_info.fragstotal,
+	    config.sample_count);
+
+	/* Minimal engine: read input and copy it to the output */
+	for (;;) {
+		ret = read(config.fd, ibuf, bytes);
+		if (ret < bytes) {
+			fprintf(stderr, "Requested %d bytes, but read %d!\n",
+			    bytes, ret);
+			break;
+		}
+		oss_split(&config, (sample_t *)ibuf, channels);
+		/* All processing will happen here */
+		oss_merge(&config, channels, (sample_t *)obuf);
+		ret = write(config.fd, obuf, bytes);
+		if (ret < bytes) {
+			fprintf(stderr, "Requested %d bytes, but wrote %d!\n",
+			    bytes, ret);
+			break;
+		}
+	}
+
+	/* Cleanup */
+	free(channels);
+	free(obuf);
+	free(ibuf);
+	close(config.fd);
+
+	return (0);
+}

share/examples/sound/oss/basic.c

@@ -1,99 +0,0 @@
-/*
- * SPDX-License-Identifier: BSD-2-Clause
- *
- * Copyright (c) 2021 Goran Mekić
- *
- * 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 "ossinit.h"
-
-int
-main()
-{
-	config_t config = {
-		.device = "/dev/dsp",
-		.channels = -1,
-		.format = format,
-		.frag = -1,
-		.sample_rate = 48000,
-		.sample_size = sizeof(sample_t),
-		.buffer_info.fragments = -1,
-		.mmap = 0,
-	};
-
-	/* Initialize device */
-	oss_init(&config);
-
-	/*
-	 * Allocate input and output buffers so that their size match
-	 * frag_size
-	 */
-	int ret;
-	int bytes = config.buffer_info.bytes;
-	int8_t *ibuf = malloc(bytes);
-	int8_t *obuf = malloc(bytes);
-	sample_t *channels = malloc(bytes);
-
-	printf(
-	    "bytes: %d, fragments: %d, fragsize: %d, fragstotal: %d, samples: %d\n",
-	    bytes,
-	    config.buffer_info.fragments,
-	    config.buffer_info.fragsize,
-	    config.buffer_info.fragstotal,
-	    config.sample_count
-	    );
-
-	/* Minimal engine: read input and copy it to the output */
-	for (;;) {
-		ret = read(config.fd, ibuf, bytes);
-		if (ret < bytes) {
-			fprintf(
-			    stderr,
-			    "Requested %d bytes, but read %d!\n",
-			    bytes,
-			    ret
-			    );
-			break;
-		}
-		oss_split(&config, (sample_t *)ibuf, channels);
-		/* All processing will happen here */
-		oss_merge(&config, channels, (sample_t *)obuf);
-		ret = write(config.fd, obuf, bytes);
-		if (ret < bytes) {
-			fprintf(
-			    stderr,
-			    "Requested %d bytes, but wrote %d!\n",
-			    bytes,
-			    ret
-			    );
-			break;
-		}
-	}
-
-	/* Cleanup */
-	free(channels);
-	free(obuf);
-	free(ibuf);
-	close(config.fd);
-	return (0);
-}