/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2008-2009 Ariff Abdullah <ariff@FreeBSD.org>
 * All rights reserved.
 * Copyright (c) 2024-2025 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.
 */

/*
 * feeder_matrix: Generic any-to-any channel matrixing. Probably not the
 *                accurate way of doing things, but it should be fast and
 *                transparent enough, not to mention capable of handling
 *                possible non-standard way of multichannel interleaving
 *                order. In other words, it is tough to break.
 *
 * The Good:
 * + very generic and compact, provided that the supplied matrix map is in a
 *   sane form.
 * + should be fast enough.
 *
 * The Bad:
 * + somebody might disagree with it.
 * + 'matrix' is kind of 0x7a69, due to prolong mental block.
 */

#ifdef _KERNEL
#ifdef HAVE_KERNEL_OPTION_HEADERS
#include "opt_snd.h"
#endif
#include <dev/sound/pcm/sound.h>
#include <dev/sound/pcm/pcm.h>
#include "feeder_if.h"

#define SND_USE_FXDIV
#include "snd_fxdiv_gen.h"
#endif

#define FEEDMATRIX_RESERVOIR    (SND_CHN_MAX * PCM_32_BPS)

#define SND_CHN_T_EOF           0x00e0fe0f
#define SND_CHN_T_NULL          0x0e0e0e0e

struct feed_matrix_info {
        uint32_t fmt;
        uint32_t bps;
        uint32_t ialign, oalign;
        uint32_t in, out;
        struct {
                int chn[SND_CHN_T_MAX + 1];
                int mul, shift;
        } matrix[SND_CHN_T_MAX + 1];
        uint8_t reservoir[FEEDMATRIX_RESERVOIR];
};

static struct pcmchan_matrix feeder_matrix_maps[SND_CHN_MATRIX_MAX] = {
        [SND_CHN_MATRIX_1_0] = SND_CHN_MATRIX_MAP_1_0,
        [SND_CHN_MATRIX_2_0] = SND_CHN_MATRIX_MAP_2_0,
        [SND_CHN_MATRIX_2_1] = SND_CHN_MATRIX_MAP_2_1,
        [SND_CHN_MATRIX_3_0] = SND_CHN_MATRIX_MAP_3_0,
        [SND_CHN_MATRIX_3_1] = SND_CHN_MATRIX_MAP_3_1,
        [SND_CHN_MATRIX_4_0] = SND_CHN_MATRIX_MAP_4_0,
        [SND_CHN_MATRIX_4_1] = SND_CHN_MATRIX_MAP_4_1,
        [SND_CHN_MATRIX_5_0] = SND_CHN_MATRIX_MAP_5_0,
        [SND_CHN_MATRIX_5_1] = SND_CHN_MATRIX_MAP_5_1,
        [SND_CHN_MATRIX_6_0] = SND_CHN_MATRIX_MAP_6_0,
        [SND_CHN_MATRIX_6_1] = SND_CHN_MATRIX_MAP_6_1,
        [SND_CHN_MATRIX_7_0] = SND_CHN_MATRIX_MAP_7_0,
        [SND_CHN_MATRIX_7_1] = SND_CHN_MATRIX_MAP_7_1
};

static int feeder_matrix_default_ids[9] = {
        [0] = SND_CHN_MATRIX_UNKNOWN,
        [1] = SND_CHN_MATRIX_1,
        [2] = SND_CHN_MATRIX_2,
        [3] = SND_CHN_MATRIX_3,
        [4] = SND_CHN_MATRIX_4,
        [5] = SND_CHN_MATRIX_5,
        [6] = SND_CHN_MATRIX_6,
        [7] = SND_CHN_MATRIX_7,
        [8] = SND_CHN_MATRIX_8
};

#ifdef _KERNEL
#define FEEDMATRIX_CLIP_CHECK(...)
#else
#define FEEDMATRIX_CLIP_CHECK(v, BIT)   do {                            \
        if ((v) < PCM_S##BIT##_MIN || (v) > PCM_S##BIT##_MAX)           \
            errx(1, "\n\n%s(): Sample clipping: %jd\n",                 \
                __func__, (intmax_t)(v));                               \
} while (0)
#endif

__always_inline static void
feed_matrix_apply(struct feed_matrix_info *info, uint8_t *src, uint8_t *dst,
    uint32_t count, const uint32_t fmt)
{
        intpcm64_t accum;
        intpcm_t v;
        int i, j;

        do {
                for (i = 0; info->matrix[i].chn[0] != SND_CHN_T_EOF; i++) {
                        if (info->matrix[i].chn[0] == SND_CHN_T_NULL) {
                                pcm_sample_write(dst, 0, fmt);
                                dst += info->bps;
                                continue;
                        } else if (info->matrix[i].chn[1] == SND_CHN_T_EOF) {
                                v = pcm_sample_read(src +
                                    info->matrix[i].chn[0], fmt);
                                pcm_sample_write(dst, v, fmt);
                                dst += info->bps;
                                continue;
                        }

                        accum = 0;
                        for (j = 0; info->matrix[i].chn[j] != SND_CHN_T_EOF;
                            j++) {
                                v = pcm_sample_read(src +
                                    info->matrix[i].chn[j], fmt);
                                accum += v;
                        }

                        accum = (accum * info->matrix[i].mul) >>
                            info->matrix[i].shift;

                        FEEDMATRIX_CLIP_CHECK(accum, AFMT_BIT(fmt));

                        v = pcm_clamp(accum, fmt);
                        pcm_sample_write(dst, v, fmt);
                        dst += info->bps;
                }
                src += info->ialign;
        } while (--count != 0);
}

static void
feed_matrix_reset(struct feed_matrix_info *info)
{
        uint32_t i, j;

        for (i = 0; i < nitems(info->matrix); i++) {
                for (j = 0;
                    j < (sizeof(info->matrix[i].chn) /
                    sizeof(info->matrix[i].chn[0])); j++) {
                        info->matrix[i].chn[j] = SND_CHN_T_EOF;
                }
                info->matrix[i].mul   = 1;
                info->matrix[i].shift = 0;
        }
}

static int
feed_matrix_setup(struct feed_matrix_info *info, struct pcmchan_matrix *m_in,
    struct pcmchan_matrix *m_out)
{
        uint32_t i, j, ch, in_mask, merge_mask;
        int mul, shift;

        if (info == NULL || m_in == NULL || m_out == NULL ||
            AFMT_CHANNEL(info->in) != m_in->channels ||
            AFMT_CHANNEL(info->out) != m_out->channels ||
            m_in->channels < SND_CHN_MIN || m_in->channels > SND_CHN_MAX ||
            m_out->channels < SND_CHN_MIN || m_out->channels > SND_CHN_MAX)
                return (EINVAL);

        feed_matrix_reset(info);

        /*
         * If both in and out are part of standard matrix and identical, skip
         * everything altogether.
         */
        if (m_in->id == m_out->id && !(m_in->id < SND_CHN_MATRIX_BEGIN ||
            m_in->id > SND_CHN_MATRIX_END))
                return (0);

        /*
         * Special case for mono input matrix. If the output supports
         * possible 'center' channel, route it there. Otherwise, let it be
         * matrixed to left/right.
         */
        if (m_in->id == SND_CHN_MATRIX_1_0) {
                if (m_out->id == SND_CHN_MATRIX_1_0)
                        in_mask = SND_CHN_T_MASK_FL;
                else if (m_out->mask & SND_CHN_T_MASK_FC)
                        in_mask = SND_CHN_T_MASK_FC;
                else
                        in_mask = SND_CHN_T_MASK_FL | SND_CHN_T_MASK_FR;
        } else
                in_mask = m_in->mask;

        /* Merge, reduce, expand all possibilites. */
        for (ch = SND_CHN_T_BEGIN; ch <= SND_CHN_T_END &&
            m_out->map[ch].type != SND_CHN_T_MAX; ch += SND_CHN_T_STEP) {
                merge_mask = m_out->map[ch].members & in_mask;
                if (merge_mask == 0) {
                        info->matrix[ch].chn[0] = SND_CHN_T_NULL;
                        continue;
                }

                j = 0;
                for (i = SND_CHN_T_BEGIN; i <= SND_CHN_T_END;
                    i += SND_CHN_T_STEP) {
                        if (merge_mask & (1 << i)) {
                                if (m_in->offset[i] >= 0 &&
                                    m_in->offset[i] < (int)m_in->channels)
                                        info->matrix[ch].chn[j++] =
                                            m_in->offset[i] * info->bps;
                                else {
                                        info->matrix[ch].chn[j++] =
                                            SND_CHN_T_EOF;
                                        break;
                                }
                        }
                }

#define FEEDMATRIX_ATTN_SHIFT   16

                if (j > 1) {
                        /*
                         * XXX For channel that require accumulation from
                         * multiple channels, apply a slight attenuation to
                         * avoid clipping.
                         */
                        mul   = (1 << (FEEDMATRIX_ATTN_SHIFT - 1)) + 143 - j;
                        shift = FEEDMATRIX_ATTN_SHIFT;
                        while ((mul & 1) == 0 && shift > 0) {
                                mul >>= 1;
                                shift--;
                        }
                        info->matrix[ch].mul   = mul;
                        info->matrix[ch].shift = shift;
                }
        }

#ifndef _KERNEL
        fprintf(stderr, "Total: %d\n", ch);

        for (i = 0; info->matrix[i].chn[0] != SND_CHN_T_EOF; i++) {
                fprintf(stderr, "%d: [", i);
                for (j = 0; info->matrix[i].chn[j] != SND_CHN_T_EOF; j++) {
                        if (j != 0)
                                fprintf(stderr, ", ");
                        fprintf(stderr, "%d",
                            (info->matrix[i].chn[j] == SND_CHN_T_NULL) ?
                            0xffffffff : info->matrix[i].chn[j] / info->bps);
                }
                fprintf(stderr, "] attn: (x * %d) >> %d\n",
                    info->matrix[i].mul, info->matrix[i].shift);
        }
#endif

        return (0);
}

static int
feed_matrix_init(struct pcm_feeder *f)
{
        struct feed_matrix_info *info;
        struct pcmchan_matrix *m_in, *m_out;
        int ret;

        if (AFMT_ENCODING(f->desc.in) != AFMT_ENCODING(f->desc.out))
                return (EINVAL);

        info = malloc(sizeof(*info), M_DEVBUF, M_NOWAIT | M_ZERO);
        if (info == NULL)
                return (ENOMEM);

        info->in = f->desc.in;
        info->out = f->desc.out;
        info->fmt = AFMT_ENCODING(info->in);
        info->bps = AFMT_BPS(info->in);
        info->ialign = AFMT_ALIGN(info->in);
        info->oalign = AFMT_ALIGN(info->out);

        m_in  = feeder_matrix_format_map(info->in);
        m_out = feeder_matrix_format_map(info->out);

        ret = feed_matrix_setup(info, m_in, m_out);
        if (ret != 0) {
                free(info, M_DEVBUF);
                return (ret);
        }

        f->data = info;

        return (0);
}

static int
feed_matrix_free(struct pcm_feeder *f)
{
        struct feed_matrix_info *info;

        info = f->data;
        free(info, M_DEVBUF);

        f->data = NULL;

        return (0);
}

static int
feed_matrix_feed(struct pcm_feeder *f, struct pcm_channel *c, uint8_t *b,
    uint32_t count, void *source)
{
        struct feed_matrix_info *info;
        uint32_t j, inmax;
        uint8_t *src, *dst;

        info = f->data;
        if (info->matrix[0].chn[0] == SND_CHN_T_EOF)
                return (FEEDER_FEED(f->source, c, b, count, source));

        dst = b;
        count = SND_FXROUND(count, info->oalign);
        inmax = info->ialign + info->oalign;

        /*
         * This loop might look simmilar to other feeder_* loops, but be
         * advised: matrixing might involve overlapping (think about
         * swapping end to front or something like that). In this regard it
         * might be simmilar to feeder_format, but feeder_format works on
         * 'sample' domain where it can be fitted into single 32bit integer
         * while matrixing works on 'sample frame' domain.
         */
        do {
                if (count < info->oalign)
                        break;

                if (count < inmax) {
                        src = info->reservoir;
                        j = info->ialign;
                } else {
                        if (info->ialign == info->oalign)
                                j = count - info->oalign;
                        else if (info->ialign > info->oalign)
                                j = SND_FXROUND(count - info->oalign,
                                    info->ialign);
                        else
                                j = (SND_FXDIV(count, info->oalign) - 1) *
                                    info->ialign;
                        src = dst + count - j;
                }

                j = SND_FXDIV(FEEDER_FEED(f->source, c, src, j, source),
                    info->ialign);
                if (j == 0)
                        break;

                /* Optimize some common formats. */
                switch (info->fmt) {
                case AFMT_S16_NE:
                        feed_matrix_apply(info, src, dst, j, AFMT_S16_NE);
                        break;
                case AFMT_S24_NE:
                        feed_matrix_apply(info, src, dst, j, AFMT_S24_NE);
                        break;
                case AFMT_S32_NE:
                        feed_matrix_apply(info, src, dst, j, AFMT_S32_NE);
                        break;
                default:
                        feed_matrix_apply(info, src, dst, j, info->fmt);
                        break;
                }

                j *= info->oalign;
                dst += j;
                count -= j;

        } while (count != 0);

        return (dst - b);
}

static kobj_method_t feeder_matrix_methods[] = {
        KOBJMETHOD(feeder_init,         feed_matrix_init),
        KOBJMETHOD(feeder_free,         feed_matrix_free),
        KOBJMETHOD(feeder_feed,         feed_matrix_feed),
        KOBJMETHOD_END
};

FEEDER_DECLARE(feeder_matrix, FEEDER_MATRIX);

/* External */
int
feeder_matrix_setup(struct pcm_feeder *f, struct pcmchan_matrix *m_in,
    struct pcmchan_matrix *m_out)
{

        if (f == NULL || f->class->type != FEEDER_MATRIX || f->data == NULL)
                return (EINVAL);

        return (feed_matrix_setup(f->data, m_in, m_out));
}

/*
 * feeder_matrix_default_id(): For a given number of channels, return
 *                             default preferred id (example: both 5.1 and
 *                             6.0 are simply 6 channels, but 5.1 is more
 *                             preferable).
 */
int
feeder_matrix_default_id(uint32_t ch)
{

        if (ch < feeder_matrix_maps[SND_CHN_MATRIX_BEGIN].channels ||
            ch > feeder_matrix_maps[SND_CHN_MATRIX_END].channels)
                return (SND_CHN_MATRIX_UNKNOWN);

        return (feeder_matrix_maps[feeder_matrix_default_ids[ch]].id);
}

/*
 * feeder_matrix_default_channel_map(): Ditto, but return matrix map
 *                                      instead.
 */
struct pcmchan_matrix *
feeder_matrix_default_channel_map(uint32_t ch)
{

        if (ch < feeder_matrix_maps[SND_CHN_MATRIX_BEGIN].channels ||
            ch > feeder_matrix_maps[SND_CHN_MATRIX_END].channels)
                return (NULL);

        return (&feeder_matrix_maps[feeder_matrix_default_ids[ch]]);
}

/*
 * feeder_matrix_default_format(): For a given audio format, return the
 *                                 proper audio format based on preferable
 *                                 matrix.
 */
uint32_t
feeder_matrix_default_format(uint32_t format)
{
        struct pcmchan_matrix *m;
        uint32_t i, ch, ext;

        ch = AFMT_CHANNEL(format);
        ext = AFMT_EXTCHANNEL(format);

        if (ext != 0) {
                for (i = SND_CHN_MATRIX_BEGIN; i <= SND_CHN_MATRIX_END; i++) {
                        if (feeder_matrix_maps[i].channels == ch &&
                            feeder_matrix_maps[i].ext == ext)
                        return (SND_FORMAT(format, ch, ext));
                }
        }

        m = feeder_matrix_default_channel_map(ch);
        if (m == NULL)
                return (0x00000000);

        return (SND_FORMAT(format, ch, m->ext));
}

/*
 * feeder_matrix_format_id(): For a given audio format, return its matrix
 *                            id.
 */
int
feeder_matrix_format_id(uint32_t format)
{
        uint32_t i, ch, ext;

        ch = AFMT_CHANNEL(format);
        ext = AFMT_EXTCHANNEL(format);

        for (i = SND_CHN_MATRIX_BEGIN; i <= SND_CHN_MATRIX_END; i++) {
                if (feeder_matrix_maps[i].channels == ch &&
                    feeder_matrix_maps[i].ext == ext)
                        return (feeder_matrix_maps[i].id);
        }

        return (SND_CHN_MATRIX_UNKNOWN);
}

/*
 * feeder_matrix_format_map(): For a given audio format, return its matrix
 *                             map.
 */
struct pcmchan_matrix *
feeder_matrix_format_map(uint32_t format)
{
        uint32_t i, ch, ext;

        ch = AFMT_CHANNEL(format);
        ext = AFMT_EXTCHANNEL(format);

        for (i = SND_CHN_MATRIX_BEGIN; i <= SND_CHN_MATRIX_END; i++) {
                if (feeder_matrix_maps[i].channels == ch &&
                    feeder_matrix_maps[i].ext == ext)
                        return (&feeder_matrix_maps[i]);
        }

        return (NULL);
}

/*
 * feeder_matrix_id_map(): For a given matrix id, return its matrix map.
 */
struct pcmchan_matrix *
feeder_matrix_id_map(int id)
{

        if (id < SND_CHN_MATRIX_BEGIN || id > SND_CHN_MATRIX_END)
                return (NULL);

        return (&feeder_matrix_maps[id]);
}

/*
 * feeder_matrix_compare(): Compare the simmilarities of matrices.
 */
int
feeder_matrix_compare(struct pcmchan_matrix *m_in, struct pcmchan_matrix *m_out)
{
        uint32_t i;

        if (m_in == m_out)
                return (0);

        if (m_in->channels != m_out->channels || m_in->ext != m_out->ext ||
            m_in->mask != m_out->mask)
                return (1);

        for (i = 0; i < nitems(m_in->map); i++) {
                if (m_in->map[i].type != m_out->map[i].type)
                        return (1);
                if (m_in->map[i].type == SND_CHN_T_MAX)
                        break;
                if (m_in->map[i].members != m_out->map[i].members)
                        return (1);
                if (i <= SND_CHN_T_END) {
                        if (m_in->offset[m_in->map[i].type] !=
                            m_out->offset[m_out->map[i].type])
                                return (1);
                }
        }

        return (0);
}

/*
 * XXX 4front interpretation of "surround" is ambigous and sort of
 *     conflicting with "rear"/"back". Map it to "side". Well.. 
 *     who cares?
 */
static int snd_chn_to_oss[SND_CHN_T_MAX] = {
        [SND_CHN_T_FL] = CHID_L,
        [SND_CHN_T_FR] = CHID_R,
        [SND_CHN_T_FC] = CHID_C,
        [SND_CHN_T_LF] = CHID_LFE,
        [SND_CHN_T_SL] = CHID_LS,
        [SND_CHN_T_SR] = CHID_RS,
        [SND_CHN_T_BL] = CHID_LR,
        [SND_CHN_T_BR] = CHID_RR
};

#define SND_CHN_OSS_VALIDMASK                                           \
                        (SND_CHN_T_MASK_FL | SND_CHN_T_MASK_FR |        \
                         SND_CHN_T_MASK_FC | SND_CHN_T_MASK_LF |        \
                         SND_CHN_T_MASK_SL | SND_CHN_T_MASK_SR |        \
                         SND_CHN_T_MASK_BL | SND_CHN_T_MASK_BR)

#define SND_CHN_OSS_MAX         8
#define SND_CHN_OSS_BEGIN       CHID_L
#define SND_CHN_OSS_END         CHID_RR

static int oss_to_snd_chn[SND_CHN_OSS_END + 1] = {
        [CHID_L]   = SND_CHN_T_FL,
        [CHID_R]   = SND_CHN_T_FR,
        [CHID_C]   = SND_CHN_T_FC,
        [CHID_LFE] = SND_CHN_T_LF,
        [CHID_LS]  = SND_CHN_T_SL,
        [CHID_RS]  = SND_CHN_T_SR,
        [CHID_LR]  = SND_CHN_T_BL,
        [CHID_RR]  = SND_CHN_T_BR
};

/*
 * Used by SNDCTL_DSP_GET_CHNORDER.
 */
int
feeder_matrix_oss_get_channel_order(struct pcmchan_matrix *m,
    unsigned long long *map)
{
        unsigned long long tmpmap;
        uint32_t i;

        if (m == NULL || map == NULL || (m->mask & ~SND_CHN_OSS_VALIDMASK) ||
            m->channels > SND_CHN_OSS_MAX)
                return (EINVAL);

        tmpmap = 0x0000000000000000ULL;

        for (i = 0; i < SND_CHN_OSS_MAX && m->map[i].type != SND_CHN_T_MAX;
            i++) {
                if ((1 << m->map[i].type) & ~SND_CHN_OSS_VALIDMASK)
                        return (EINVAL);
                tmpmap |=
                    (unsigned long long)snd_chn_to_oss[m->map[i].type] <<
                    (i * 4);
        }

        *map = tmpmap;

        return (0);
}

/*
 * Used by SNDCTL_DSP_SET_CHNORDER.
 */
int
feeder_matrix_oss_set_channel_order(struct pcmchan_matrix *m,
    unsigned long long *map)
{
        struct pcmchan_matrix tmp;
        uint32_t chmask, i;
        int ch, cheof;

        if (m == NULL || map == NULL || (m->mask & ~SND_CHN_OSS_VALIDMASK) ||
            m->channels > SND_CHN_OSS_MAX || (*map & 0xffffffff00000000ULL))
                return (EINVAL);

        tmp = *m;
        tmp.channels = 0;
        tmp.ext = 0;
        tmp.mask = 0;
        memset(tmp.offset, -1, sizeof(tmp.offset));
        cheof = 0;

        for (i = 0; i < SND_CHN_OSS_MAX; i++) {
                ch = (*map >> (i * 4)) & 0xf;
                if (ch < SND_CHN_OSS_BEGIN) {
                        if (cheof == 0 && m->map[i].type != SND_CHN_T_MAX)
                                return (EINVAL);
                        cheof++;
                        tmp.map[i] = m->map[i];
                        continue;
                } else if (ch > SND_CHN_OSS_END)
                        return (EINVAL);
                else if (cheof != 0)
                        return (EINVAL);
                ch = oss_to_snd_chn[ch];
                chmask = 1 << ch;
                /* channel not exist in matrix */
                if (!(chmask & m->mask))
                        return (EINVAL);
                /* duplicated channel */
                if (chmask & tmp.mask)
                        return (EINVAL);
                tmp.map[i] = m->map[m->offset[ch]];
                if (tmp.map[i].type != ch)
                        return (EINVAL);
                tmp.offset[ch] = i;
                tmp.mask |= chmask;
                tmp.channels++;
                if (chmask & SND_CHN_T_MASK_LF)
                        tmp.ext++;
        }

        if (tmp.channels != m->channels || tmp.ext != m->ext ||
            tmp.mask != m->mask ||
            tmp.map[m->channels].type != SND_CHN_T_MAX)
                return (EINVAL);

        *m = tmp;

        return (0);
}