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      1 /*	$NetBSD: oss_dsp.c,v 1.2 2021/06/08 19:26:48 nia Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1997-2021 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 __RCSID("$NetBSD: oss_dsp.c,v 1.2 2021/06/08 19:26:48 nia Exp $");
     31 
     32 #include <sys/audioio.h>
     33 #include <stdbool.h>
     34 #include <errno.h>
     35 #include "internal.h"
     36 
     37 #define GETPRINFO(info, name)	\
     38 	(((info)->mode == AUMODE_RECORD) \
     39 	    ? (info)->record.name : (info)->play.name)
     40 
     41 static int encoding_to_format(u_int, u_int);
     42 static int format_to_encoding(int, struct audio_info *);
     43 
     44 static int get_vol(u_int, u_char);
     45 static void set_vol(int, int, bool);
     46 
     47 static void set_channels(int, int, int);
     48 
     49 oss_private int
     50 _oss_dsp_ioctl(int fd, unsigned long com, void *argp)
     51 {
     52 
     53 	struct audio_info tmpinfo, hwfmt;
     54 	struct audio_offset tmpoffs;
     55 	struct audio_buf_info bufinfo;
     56 	struct audio_errinfo *tmperrinfo;
     57 	struct count_info cntinfo;
     58 	struct audio_encoding tmpenc;
     59 	u_int u;
     60 	int perrors, rerrors;
     61 	static int totalperrors = 0;
     62 	static int totalrerrors = 0;
     63 	oss_mixer_enuminfo *ei;
     64 	oss_count_t osscount;
     65 	int idat;
     66 	int retval;
     67 
     68 	idat = 0;
     69 
     70 	switch (com) {
     71 	case SNDCTL_DSP_HALT_INPUT:
     72 	case SNDCTL_DSP_HALT_OUTPUT:
     73 	case SNDCTL_DSP_RESET:
     74 		retval = ioctl(fd, AUDIO_FLUSH, 0);
     75 		if (retval < 0)
     76 			return retval;
     77 		break;
     78 	case SNDCTL_DSP_SYNC:
     79 		retval = ioctl(fd, AUDIO_DRAIN, 0);
     80 		if (retval < 0)
     81 			return retval;
     82 		break;
     83 	case SNDCTL_DSP_GETERROR:
     84 		tmperrinfo = (struct audio_errinfo *)argp;
     85 		if (tmperrinfo == NULL) {
     86 			errno = EINVAL;
     87 			return -1;
     88 		}
     89 		memset(tmperrinfo, 0, sizeof(struct audio_errinfo));
     90 		if ((retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo)) < 0)
     91 			return retval;
     92 		/*
     93 		 * OSS requires that we return counters that are relative to
     94 		 * the last call. We must maintain state here...
     95 		 */
     96 		if (ioctl(fd, AUDIO_PERROR, &perrors) != -1) {
     97 			perrors /= ((tmpinfo.play.precision / NBBY) *
     98 			    tmpinfo.play.channels);
     99 			tmperrinfo->play_underruns =
    100 			    (perrors / tmpinfo.blocksize) - totalperrors;
    101 			totalperrors += tmperrinfo->play_underruns;
    102 		}
    103 		if (ioctl(fd, AUDIO_RERROR, &rerrors) != -1) {
    104 			rerrors /= ((tmpinfo.record.precision / NBBY) *
    105 			    tmpinfo.record.channels);
    106 			tmperrinfo->rec_overruns =
    107 			    (rerrors / tmpinfo.blocksize) - totalrerrors;
    108 			totalrerrors += tmperrinfo->rec_overruns;
    109 		}
    110 		break;
    111 	case SNDCTL_DSP_COOKEDMODE:
    112 		/*
    113 		 * NetBSD is always running in "cooked mode" - the kernel
    114 		 * always performs format conversions.
    115 		 */
    116 		INTARG = 1;
    117 		break;
    118 	case SNDCTL_DSP_POST:
    119 		/* This call is merely advisory, and may be a nop. */
    120 		break;
    121 	case SNDCTL_DSP_SPEED:
    122 		/*
    123 		 * In Solaris, 0 is used a special value to query the
    124 		 * current rate. This seems useful to support.
    125 		 */
    126 		if (INTARG == 0) {
    127 			retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    128 			if (retval < 0)
    129 				return retval;
    130 			retval = ioctl(fd, AUDIO_GETFORMAT, &hwfmt);
    131 			if (retval < 0)
    132 				return retval;
    133 			INTARG = (tmpinfo.mode == AUMODE_RECORD) ?
    134 			    hwfmt.record.sample_rate :
    135 			    hwfmt.play.sample_rate;
    136 		}
    137 		/*
    138 		 * Conform to kernel limits.
    139 		 * NetBSD will reject unsupported sample rates, but OSS
    140 		 * applications need to be able to negotiate a supported one.
    141 		 */
    142 		if (INTARG < 1000)
    143 			INTARG = 1000;
    144 		if (INTARG > 192000)
    145 			INTARG = 192000;
    146 		AUDIO_INITINFO(&tmpinfo);
    147 		tmpinfo.play.sample_rate =
    148 		tmpinfo.record.sample_rate = INTARG;
    149 		retval = ioctl(fd, AUDIO_SETINFO, &tmpinfo);
    150 		if (retval < 0)
    151 			return retval;
    152 		/* FALLTHRU */
    153 	case SOUND_PCM_READ_RATE:
    154 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    155 		if (retval < 0)
    156 			return retval;
    157 		INTARG = GETPRINFO(&tmpinfo, sample_rate);
    158 		break;
    159 	case SNDCTL_DSP_STEREO:
    160 		AUDIO_INITINFO(&tmpinfo);
    161 		tmpinfo.play.channels =
    162 		tmpinfo.record.channels = INTARG ? 2 : 1;
    163 		(void) ioctl(fd, AUDIO_SETINFO, &tmpinfo);
    164 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    165 		if (retval < 0)
    166 			return retval;
    167 		INTARG = GETPRINFO(&tmpinfo, channels) - 1;
    168 		break;
    169 	case SNDCTL_DSP_GETBLKSIZE:
    170 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    171 		if (retval < 0)
    172 			return retval;
    173 		INTARG = tmpinfo.blocksize;
    174 		break;
    175 	case SNDCTL_DSP_SETFMT:
    176 		AUDIO_INITINFO(&tmpinfo);
    177 		retval = format_to_encoding(INTARG, &tmpinfo);
    178 		if (retval < 0) {
    179 			/*
    180 			 * OSSv4 specifies that if an invalid format is chosen
    181 			 * by an application then a sensible format supported
    182 			 * by the hardware is returned.
    183 			 *
    184 			 * In this case, we pick the current hardware format.
    185 			 */
    186 			retval = ioctl(fd, AUDIO_GETFORMAT, &hwfmt);
    187 			if (retval < 0)
    188 				return retval;
    189 			retval = ioctl(fd, AUDIO_GETINFO, &tmpinfo);
    190 			if (retval < 0)
    191 				return retval;
    192 			tmpinfo.play.encoding =
    193 			tmpinfo.record.encoding =
    194 			    (tmpinfo.mode == AUMODE_RECORD) ?
    195 			    hwfmt.record.encoding : hwfmt.play.encoding;
    196 			tmpinfo.play.precision =
    197 			tmpinfo.record.precision =
    198 			    (tmpinfo.mode == AUMODE_RECORD) ?
    199 			    hwfmt.record.precision : hwfmt.play.precision ;
    200 		}
    201 		/*
    202 		 * In the post-kernel-mixer world, assume that any error means
    203 		 * it's fatal rather than an unsupported format being selected.
    204 		 */
    205 		retval = ioctl(fd, AUDIO_SETINFO, &tmpinfo);
    206 		if (retval < 0)
    207 			return retval;
    208 		/* FALLTHRU */
    209 	case SOUND_PCM_READ_BITS:
    210 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    211 		if (retval < 0)
    212 			return retval;
    213 		if (tmpinfo.mode == AUMODE_RECORD)
    214 			retval = encoding_to_format(tmpinfo.record.encoding,
    215 			    tmpinfo.record.precision);
    216 		else
    217 			retval = encoding_to_format(tmpinfo.play.encoding,
    218 			    tmpinfo.play.precision);
    219 		if (retval < 0) {
    220 			errno = EINVAL;
    221 			return retval;
    222 		}
    223 		INTARG = retval;
    224 		break;
    225 	case SNDCTL_DSP_CHANNELS:
    226 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    227 		if (retval < 0)
    228 			return retval;
    229 		set_channels(fd, tmpinfo.mode, INTARG);
    230 		/* FALLTHRU */
    231 	case SOUND_PCM_READ_CHANNELS:
    232 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    233 		if (retval < 0)
    234 			return retval;
    235 		INTARG = GETPRINFO(&tmpinfo, channels);
    236 		break;
    237 	case SOUND_PCM_WRITE_FILTER:
    238 	case SOUND_PCM_READ_FILTER:
    239 		errno = EINVAL;
    240 		return -1; /* XXX unimplemented */
    241 	case SNDCTL_DSP_SUBDIVIDE:
    242 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    243 		if (retval < 0)
    244 			return retval;
    245 		idat = INTARG;
    246 		if (idat == 0)
    247 			idat = tmpinfo.play.buffer_size / tmpinfo.blocksize;
    248 		idat = (tmpinfo.play.buffer_size / idat) & -4;
    249 		AUDIO_INITINFO(&tmpinfo);
    250 		tmpinfo.blocksize = idat;
    251 		retval = ioctl(fd, AUDIO_SETINFO, &tmpinfo);
    252 		if (retval < 0)
    253 			return retval;
    254 		INTARG = tmpinfo.play.buffer_size / tmpinfo.blocksize;
    255 		break;
    256 	case SNDCTL_DSP_SETFRAGMENT:
    257 		AUDIO_INITINFO(&tmpinfo);
    258 		idat = INTARG;
    259 		tmpinfo.blocksize = 1 << (idat & 0xffff);
    260 		tmpinfo.hiwat = ((unsigned)idat >> 16) & 0x7fff;
    261 		if (tmpinfo.hiwat == 0)	/* 0 means set to max */
    262 			tmpinfo.hiwat = 65536;
    263 		(void) ioctl(fd, AUDIO_SETINFO, &tmpinfo);
    264 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    265 		if (retval < 0)
    266 			return retval;
    267 		u = tmpinfo.blocksize;
    268 		for(idat = 0; u > 1; idat++, u >>= 1)
    269 			;
    270 		idat |= (tmpinfo.hiwat & 0x7fff) << 16;
    271 		INTARG = idat;
    272 		break;
    273 	case SNDCTL_DSP_GETFMTS:
    274 		for(idat = 0, tmpenc.index = 0;
    275 		    ioctl(fd, AUDIO_GETENC, &tmpenc) == 0;
    276 		    tmpenc.index++) {
    277 			retval = encoding_to_format(tmpenc.encoding,
    278 			    tmpenc.precision);
    279 			if (retval != -1)
    280 				idat |= retval;
    281 		}
    282 		INTARG = idat;
    283 		break;
    284 	case SNDCTL_DSP_GETOSPACE:
    285 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    286 		if (retval < 0)
    287 			return retval;
    288 		bufinfo.fragsize = tmpinfo.blocksize;
    289 		bufinfo.fragments = tmpinfo.hiwat - (tmpinfo.play.seek
    290 		    + tmpinfo.blocksize - 1) / tmpinfo.blocksize;
    291 		bufinfo.fragstotal = tmpinfo.hiwat;
    292 		bufinfo.bytes = tmpinfo.hiwat * tmpinfo.blocksize
    293 		    - tmpinfo.play.seek;
    294 		*(struct audio_buf_info *)argp = bufinfo;
    295 		break;
    296 	case SNDCTL_DSP_GETISPACE:
    297 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    298 		if (retval < 0)
    299 			return retval;
    300 		bufinfo.fragsize = tmpinfo.blocksize;
    301 		bufinfo.fragments = tmpinfo.record.seek / tmpinfo.blocksize;
    302 		bufinfo.fragstotal =
    303 		    tmpinfo.record.buffer_size / tmpinfo.blocksize;
    304 		bufinfo.bytes = tmpinfo.record.seek;
    305 		*(struct audio_buf_info *)argp = bufinfo;
    306 		break;
    307 	case SNDCTL_DSP_NONBLOCK:
    308 		idat = 1;
    309 		retval = ioctl(fd, FIONBIO, &idat);
    310 		if (retval < 0)
    311 			return retval;
    312 		break;
    313 	case SNDCTL_DSP_GETCAPS:
    314 		retval = _oss_get_caps(fd, (int *)argp);
    315 		if (retval < 0)
    316 			return retval;
    317 		break;
    318 	case SNDCTL_DSP_SETTRIGGER:
    319 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    320 		if (retval < 0)
    321 			return retval;
    322 		AUDIO_INITINFO(&tmpinfo);
    323 		if (tmpinfo.mode & AUMODE_PLAY)
    324 			tmpinfo.play.pause = (INTARG & PCM_ENABLE_OUTPUT) == 0;
    325 		if (tmpinfo.mode & AUMODE_RECORD)
    326 			tmpinfo.record.pause = (INTARG & PCM_ENABLE_INPUT) == 0;
    327 		(void)ioctl(fd, AUDIO_SETINFO, &tmpinfo);
    328 		/* FALLTHRU */
    329 	case SNDCTL_DSP_GETTRIGGER:
    330 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    331 		if (retval < 0)
    332 			return retval;
    333 		idat = 0;
    334 		if ((tmpinfo.mode & AUMODE_PLAY) && !tmpinfo.play.pause)
    335 			idat |= PCM_ENABLE_OUTPUT;
    336 		if ((tmpinfo.mode & AUMODE_RECORD) && !tmpinfo.record.pause)
    337 			idat |= PCM_ENABLE_INPUT;
    338 		INTARG = idat;
    339 		break;
    340 	case SNDCTL_DSP_GETIPTR:
    341 		retval = ioctl(fd, AUDIO_GETIOFFS, &tmpoffs);
    342 		if (retval < 0)
    343 			return retval;
    344 		cntinfo.bytes = tmpoffs.samples;
    345 		cntinfo.blocks = tmpoffs.deltablks;
    346 		cntinfo.ptr = tmpoffs.offset;
    347 		*(struct count_info *)argp = cntinfo;
    348 		break;
    349 	case SNDCTL_DSP_CURRENT_IPTR:
    350 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    351 		if (retval < 0)
    352 			return retval;
    353 		/* XXX: 'samples' may wrap */
    354 		memset(osscount.filler, 0, sizeof(osscount.filler));
    355 		osscount.samples = tmpinfo.record.samples /
    356 		    ((tmpinfo.record.precision / NBBY) *
    357 			tmpinfo.record.channels);
    358 		osscount.fifo_samples = tmpinfo.record.seek /
    359 		    ((tmpinfo.record.precision / NBBY) *
    360 			tmpinfo.record.channels);
    361 		*(oss_count_t *)argp = osscount;
    362 		break;
    363 	case SNDCTL_DSP_GETOPTR:
    364 		retval = ioctl(fd, AUDIO_GETOOFFS, &tmpoffs);
    365 		if (retval < 0)
    366 			return retval;
    367 		cntinfo.bytes = tmpoffs.samples;
    368 		cntinfo.blocks = tmpoffs.deltablks;
    369 		cntinfo.ptr = tmpoffs.offset;
    370 		*(struct count_info *)argp = cntinfo;
    371 		break;
    372 	case SNDCTL_DSP_CURRENT_OPTR:
    373 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    374 		if (retval < 0)
    375 			return retval;
    376 		/* XXX: 'samples' may wrap */
    377 		memset(osscount.filler, 0, sizeof(osscount.filler));
    378 		osscount.samples = tmpinfo.play.samples /
    379 		    ((tmpinfo.play.precision / NBBY) *
    380 			tmpinfo.play.channels);
    381 		osscount.fifo_samples = tmpinfo.play.seek /
    382 		    ((tmpinfo.play.precision / NBBY) *
    383 			tmpinfo.play.channels);
    384 		*(oss_count_t *)argp = osscount;
    385 		break;
    386 	case SNDCTL_DSP_SETPLAYVOL:
    387 		set_vol(fd, INTARG, false);
    388 		/* FALLTHRU */
    389 	case SNDCTL_DSP_GETPLAYVOL:
    390 		retval = ioctl(fd, AUDIO_GETINFO, &tmpinfo);
    391 		if (retval < 0)
    392 			return retval;
    393 		INTARG = get_vol(tmpinfo.play.gain, tmpinfo.play.balance);
    394 		break;
    395 	case SNDCTL_DSP_SETRECVOL:
    396 		set_vol(fd, INTARG, true);
    397 		/* FALLTHRU */
    398 	case SNDCTL_DSP_GETRECVOL:
    399 		retval = ioctl(fd, AUDIO_GETINFO, &tmpinfo);
    400 		if (retval < 0)
    401 			return retval;
    402 		INTARG = get_vol(tmpinfo.record.gain, tmpinfo.record.balance);
    403 		break;
    404 	case SNDCTL_DSP_SKIP:
    405 	case SNDCTL_DSP_SILENCE:
    406 		errno = EINVAL;
    407 		return -1;
    408 	case SNDCTL_DSP_SETDUPLEX:
    409 		idat = 1;
    410 		retval = ioctl(fd, AUDIO_SETFD, &idat);
    411 		if (retval < 0)
    412 			return retval;
    413 		break;
    414 	case SNDCTL_DSP_GETODELAY:
    415 		retval = ioctl(fd, AUDIO_GETBUFINFO, &tmpinfo);
    416 		if (retval < 0)
    417 			return retval;
    418 		idat = tmpinfo.play.seek + tmpinfo.blocksize / 2;
    419 		INTARG = idat;
    420 		break;
    421 	case SNDCTL_DSP_PROFILE:
    422 		/* This gives just a hint to the driver,
    423 		 * implementing it as a NOP is ok
    424 		 */
    425 		break;
    426 	case SNDCTL_DSP_MAPINBUF:
    427 	case SNDCTL_DSP_MAPOUTBUF:
    428 	case SNDCTL_DSP_SETSYNCRO:
    429 		errno = EINVAL;
    430 		return -1; /* XXX unimplemented */
    431 	case SNDCTL_DSP_GET_PLAYTGT_NAMES:
    432 	case SNDCTL_DSP_GET_RECSRC_NAMES:
    433 		ei = (oss_mixer_enuminfo *)argp;
    434 		ei->nvalues = 1;
    435 		ei->version = 0;
    436 		ei->strindex[0] = 0;
    437 		strlcpy(ei->strings, "primary", OSS_ENUM_STRINGSIZE);
    438 		break;
    439 	case SNDCTL_DSP_SET_PLAYTGT:
    440 	case SNDCTL_DSP_SET_RECSRC:
    441 	case SNDCTL_DSP_GET_PLAYTGT:
    442 	case SNDCTL_DSP_GET_RECSRC:
    443 		/* We have one recording source and play target. */
    444 		INTARG = 0;
    445 		break;
    446 	default:
    447 		errno = EINVAL;
    448 		return -1;
    449 	}
    450 
    451 	return 0;
    452 }
    453 
    454 static int
    455 get_vol(u_int gain, u_char balance)
    456 {
    457 	u_int l, r;
    458 
    459 	if (balance == AUDIO_MID_BALANCE) {
    460 		l = r = gain;
    461 	} else if (balance < AUDIO_MID_BALANCE) {
    462 		l = gain;
    463 		r = (balance * gain) / AUDIO_MID_BALANCE;
    464 	} else {
    465 		r = gain;
    466 		l = ((AUDIO_RIGHT_BALANCE - balance) * gain)
    467 		    / AUDIO_MID_BALANCE;
    468 	}
    469 
    470 	return TO_OSSVOL(l) | (TO_OSSVOL(r) << 8);
    471 }
    472 
    473 static void
    474 set_vol(int fd, int volume, bool record)
    475 {
    476 	u_int lgain, rgain;
    477 	struct audio_info tmpinfo;
    478 	struct audio_prinfo *prinfo;
    479 
    480 	AUDIO_INITINFO(&tmpinfo);
    481 	prinfo = record ? &tmpinfo.record : &tmpinfo.play;
    482 
    483 	lgain = FROM_OSSVOL((volume >> 0) & 0xff);
    484 	rgain = FROM_OSSVOL((volume >> 8) & 0xff);
    485 
    486 	if (lgain == rgain) {
    487 		prinfo->gain = lgain;
    488 		prinfo->balance = AUDIO_MID_BALANCE;
    489 	} else if (lgain < rgain) {
    490 		prinfo->gain = rgain;
    491 		prinfo->balance = AUDIO_RIGHT_BALANCE -
    492 		    (AUDIO_MID_BALANCE * lgain) / rgain;
    493 	} else {
    494 		prinfo->gain = lgain;
    495 		prinfo->balance = (AUDIO_MID_BALANCE * rgain) / lgain;
    496 	}
    497 
    498 	(void)ioctl(fd, AUDIO_SETINFO, &tmpinfo);
    499 }
    500 
    501 /*
    502  * When AUDIO_SETINFO fails to set a channel count, the application's chosen
    503  * number is out of range of what the kernel allows.
    504  *
    505  * When this happens, we use the current hardware settings. This is just in
    506  * case an application is abusing SNDCTL_DSP_CHANNELS - OSSv4 always sets and
    507  * returns a reasonable value, even if it wasn't what the user requested.
    508  *
    509  * Solaris guarantees this behaviour if nchannels = 0.
    510  *
    511  * XXX: If a device is opened for both playback and recording, and supports
    512  * fewer channels for recording than playback, applications that do both will
    513  * behave very strangely. OSS doesn't allow for reporting separate channel
    514  * counts for recording and playback. This could be worked around by always
    515  * mixing recorded data up to the same number of channels as is being used
    516  * for playback.
    517  */
    518 static void
    519 set_channels(int fd, int mode, int nchannels)
    520 {
    521 	struct audio_info tmpinfo, hwfmt;
    522 
    523 	if (ioctl(fd, AUDIO_GETFORMAT, &hwfmt) < 0) {
    524 		errno = 0;
    525 		hwfmt.record.channels = hwfmt.play.channels = 2;
    526 	}
    527 
    528 	if (mode & AUMODE_PLAY) {
    529 		AUDIO_INITINFO(&tmpinfo);
    530 		tmpinfo.play.channels = nchannels;
    531 		if (ioctl(fd, AUDIO_SETINFO, &tmpinfo) < 0) {
    532 			errno = 0;
    533 			AUDIO_INITINFO(&tmpinfo);
    534 			tmpinfo.play.channels = hwfmt.play.channels;
    535 			(void)ioctl(fd, AUDIO_SETINFO, &tmpinfo);
    536 		}
    537 	}
    538 
    539 	if (mode & AUMODE_RECORD) {
    540 		AUDIO_INITINFO(&tmpinfo);
    541 		tmpinfo.record.channels = nchannels;
    542 		if (ioctl(fd, AUDIO_SETINFO, &tmpinfo) < 0) {
    543 			errno = 0;
    544 			AUDIO_INITINFO(&tmpinfo);
    545 			tmpinfo.record.channels = hwfmt.record.channels;
    546 			(void)ioctl(fd, AUDIO_SETINFO, &tmpinfo);
    547 		}
    548 	}
    549 }
    550 
    551 /* Convert a NetBSD "encoding" to a OSS "format". */
    552 static int
    553 encoding_to_format(u_int encoding, u_int precision)
    554 {
    555 	switch(encoding) {
    556 	case AUDIO_ENCODING_ULAW:
    557 		return AFMT_MU_LAW;
    558 	case AUDIO_ENCODING_ALAW:
    559 		return AFMT_A_LAW;
    560 	case AUDIO_ENCODING_SLINEAR:
    561 		if (precision == 32)
    562 			return AFMT_S32_NE;
    563 		else if (precision == 24)
    564 			return AFMT_S24_NE;
    565 		else if (precision == 16)
    566 			return AFMT_S16_NE;
    567 		return AFMT_S8;
    568 	case AUDIO_ENCODING_SLINEAR_LE:
    569 		if (precision == 32)
    570 			return AFMT_S32_LE;
    571 		else if (precision == 24)
    572 			return AFMT_S24_LE;
    573 		else if (precision == 16)
    574 			return AFMT_S16_LE;
    575 		return AFMT_S8;
    576 	case AUDIO_ENCODING_SLINEAR_BE:
    577 		if (precision == 32)
    578 			return AFMT_S32_BE;
    579 		else if (precision == 24)
    580 			return AFMT_S24_BE;
    581 		else if (precision == 16)
    582 			return AFMT_S16_BE;
    583 		return AFMT_S8;
    584 	case AUDIO_ENCODING_ULINEAR:
    585 		if (precision == 16)
    586 			return AFMT_U16_NE;
    587 		return AFMT_U8;
    588 	case AUDIO_ENCODING_ULINEAR_LE:
    589 		if (precision == 16)
    590 			return AFMT_U16_LE;
    591 		return AFMT_U8;
    592 	case AUDIO_ENCODING_ULINEAR_BE:
    593 		if (precision == 16)
    594 			return AFMT_U16_BE;
    595 		return AFMT_U8;
    596 	case AUDIO_ENCODING_ADPCM:
    597 		return AFMT_IMA_ADPCM;
    598 	case AUDIO_ENCODING_AC3:
    599 		return AFMT_AC3;
    600 	}
    601 	return -1;
    602 }
    603 
    604 /* Convert an OSS "format" to a NetBSD "encoding". */
    605 static int
    606 format_to_encoding(int fmt, struct audio_info *tmpinfo)
    607 {
    608 	switch (fmt) {
    609 	case AFMT_MU_LAW:
    610 		tmpinfo->record.precision =
    611 		tmpinfo->play.precision = 8;
    612 		tmpinfo->record.encoding =
    613 		tmpinfo->play.encoding = AUDIO_ENCODING_ULAW;
    614 		return 0;
    615 	case AFMT_A_LAW:
    616 		tmpinfo->record.precision =
    617 		tmpinfo->play.precision = 8;
    618 		tmpinfo->record.encoding =
    619 		tmpinfo->play.encoding = AUDIO_ENCODING_ALAW;
    620 		return 0;
    621 	case AFMT_U8:
    622 		tmpinfo->record.precision =
    623 		tmpinfo->play.precision = 8;
    624 		tmpinfo->record.encoding =
    625 		tmpinfo->play.encoding = AUDIO_ENCODING_ULINEAR;
    626 		return 0;
    627 	case AFMT_S8:
    628 		tmpinfo->record.precision =
    629 		tmpinfo->play.precision = 8;
    630 		tmpinfo->record.encoding =
    631 		tmpinfo->play.encoding = AUDIO_ENCODING_SLINEAR;
    632 		return 0;
    633 	case AFMT_S16_LE:
    634 		tmpinfo->record.precision =
    635 		tmpinfo->play.precision = 16;
    636 		tmpinfo->record.encoding =
    637 		tmpinfo->play.encoding = AUDIO_ENCODING_SLINEAR_LE;
    638 		return 0;
    639 	case AFMT_S16_BE:
    640 		tmpinfo->record.precision =
    641 		tmpinfo->play.precision = 16;
    642 		tmpinfo->record.encoding =
    643 		tmpinfo->play.encoding = AUDIO_ENCODING_SLINEAR_BE;
    644 		return 0;
    645 	case AFMT_U16_LE:
    646 		tmpinfo->record.precision =
    647 		tmpinfo->play.precision = 16;
    648 		tmpinfo->record.encoding =
    649 		tmpinfo->play.encoding = AUDIO_ENCODING_ULINEAR_LE;
    650 		return 0;
    651 	case AFMT_U16_BE:
    652 		tmpinfo->record.precision =
    653 		tmpinfo->play.precision = 16;
    654 		tmpinfo->record.encoding =
    655 		tmpinfo->play.encoding = AUDIO_ENCODING_ULINEAR_BE;
    656 		return 0;
    657 	/*
    658 	 * XXX: When the kernel supports 24-bit LPCM by default,
    659 	 * the 24-bit formats should be handled properly instead
    660 	 * of falling back to 32 bits.
    661 	 */
    662 	case AFMT_S24_PACKED:
    663 	case AFMT_S24_LE:
    664 	case AFMT_S32_LE:
    665 		tmpinfo->record.precision =
    666 		tmpinfo->play.precision = 32;
    667 		tmpinfo->record.encoding =
    668 		tmpinfo->play.encoding = AUDIO_ENCODING_SLINEAR_LE;
    669 		return 0;
    670 	case AFMT_S24_BE:
    671 	case AFMT_S32_BE:
    672 		tmpinfo->record.precision =
    673 		tmpinfo->play.precision = 32;
    674 		tmpinfo->record.encoding =
    675 		tmpinfo->play.encoding = AUDIO_ENCODING_SLINEAR_BE;
    676 		return 0;
    677 	case AFMT_AC3:
    678 		tmpinfo->record.precision =
    679 		tmpinfo->play.precision = 16;
    680 		tmpinfo->record.encoding =
    681 		tmpinfo->play.encoding = AUDIO_ENCODING_AC3;
    682 		return 0;
    683 	}
    684 	return -1;
    685 }
    686