// SPDX-License-Identifier: LGPL-2.0+
/*
 *  Route Plug-In
 *  Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
 */

#include <linux/time.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include "pcm_plugin.h"

static void zero_areas(struct snd_pcm_plugin_channel *dvp, int ndsts,
                       snd_pcm_uframes_t frames, snd_pcm_format_t format)
{
        int dst = 0;
        for (; dst < ndsts; ++dst) {
                if (dvp->wanted)
                        snd_pcm_area_silence(&dvp->area, 0, frames, format);
                dvp->enabled = 0;
                dvp++;
        }
}

static inline void copy_area(const struct snd_pcm_plugin_channel *src_channel,
                             struct snd_pcm_plugin_channel *dst_channel,
                             snd_pcm_uframes_t frames, snd_pcm_format_t format)
{
        dst_channel->enabled = 1;
        snd_pcm_area_copy(&src_channel->area, 0, &dst_channel->area, 0, frames, format);
}

static snd_pcm_sframes_t route_transfer(struct snd_pcm_plugin *plugin,
                                        const struct snd_pcm_plugin_channel *src_channels,
                                        struct snd_pcm_plugin_channel *dst_channels,
                                        snd_pcm_uframes_t frames)
{
        int nsrcs, ndsts, dst;
        struct snd_pcm_plugin_channel *dvp;
        snd_pcm_format_t format;

        if (snd_BUG_ON(!plugin || !src_channels || !dst_channels))
                return -ENXIO;
        if (frames == 0)
                return 0;
        if (frames > dst_channels[0].frames)
                frames = dst_channels[0].frames;

        nsrcs = plugin->src_format.channels;
        ndsts = plugin->dst_format.channels;

        format = plugin->dst_format.format;
        dvp = dst_channels;
        if (nsrcs <= 1) {
                /* expand to all channels */
                for (dst = 0; dst < ndsts; ++dst) {
                        copy_area(src_channels, dvp, frames, format);
                        dvp++;
                }
                return frames;
        }

        for (dst = 0; dst < ndsts && dst < nsrcs; ++dst) {
                copy_area(src_channels, dvp, frames, format);
                dvp++;
                src_channels++;
        }
        if (dst < ndsts)
                zero_areas(dvp, ndsts - dst, frames, format);
        return frames;
}

int snd_pcm_plugin_build_route(struct snd_pcm_substream *plug,
                               struct snd_pcm_plugin_format *src_format,
                               struct snd_pcm_plugin_format *dst_format,
                               struct snd_pcm_plugin **r_plugin)
{
        struct snd_pcm_plugin *plugin;
        int err;

        if (snd_BUG_ON(!r_plugin))
                return -ENXIO;
        *r_plugin = NULL;
        if (snd_BUG_ON(src_format->rate != dst_format->rate))
                return -ENXIO;
        if (snd_BUG_ON(src_format->format != dst_format->format))
                return -ENXIO;

        err = snd_pcm_plugin_build(plug, "route conversion",
                                   src_format, dst_format, 0, &plugin);
        if (err < 0)
                return err;

        plugin->transfer = route_transfer;
        *r_plugin = plugin;
        return 0;
}