/*
 *  Linear conversion Plug-In
 *  Copyright (c) 1999 by Jaroslav Kysela <perex@perex.cz>,
 *                        Abramo Bagnara <abramo@alsa-project.org>
 *
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library General Public License as
 *   published by the Free Software Foundation; either version 2 of
 *   the License, or (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU Library General Public License for more details.
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

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

/*
 *  Basic linear conversion plugin
 */
 
struct linear_priv {
        int cvt_endian;         /* need endian conversion? */
        unsigned int src_ofs;   /* byte offset in source format */
        unsigned int dst_ofs;   /* byte soffset in destination format */
        unsigned int copy_ofs;  /* byte offset in temporary u32 data */
        unsigned int dst_bytes;         /* byte size of destination format */
        unsigned int copy_bytes;        /* bytes to copy per conversion */
        unsigned int flip; /* MSB flip for signeness, done after endian conv */
};

static inline void do_convert(struct linear_priv *data,
                              unsigned char *dst, unsigned char *src)
{
        unsigned int tmp = 0;
        unsigned char *p = (unsigned char *)&tmp;

        memcpy(p + data->copy_ofs, src + data->src_ofs, data->copy_bytes);
        if (data->cvt_endian)
                tmp = swab32(tmp);
        tmp ^= data->flip;
        memcpy(dst, p + data->dst_ofs, data->dst_bytes);
}

static void convert(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)
{
        struct linear_priv *data = (struct linear_priv *)plugin->extra_data;
        int channel;
        int nchannels = plugin->src_format.channels;
        for (channel = 0; channel < nchannels; ++channel) {
                char *src;
                char *dst;
                int src_step, dst_step;
                snd_pcm_uframes_t frames1;
                if (!src_channels[channel].enabled) {
                        if (dst_channels[channel].wanted)
                                snd_pcm_area_silence(&dst_channels[channel].area, 0, frames, plugin->dst_format.format);
                        dst_channels[channel].enabled = 0;
                        continue;
                }
                dst_channels[channel].enabled = 1;
                src = src_channels[channel].area.addr + src_channels[channel].area.first / 8;
                dst = dst_channels[channel].area.addr + dst_channels[channel].area.first / 8;
                src_step = src_channels[channel].area.step / 8;
                dst_step = dst_channels[channel].area.step / 8;
                frames1 = frames;
                while (frames1-- > 0) {
                        do_convert(data, dst, src);
                        src += src_step;
                        dst += dst_step;
                }
        }
}

static snd_pcm_sframes_t linear_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)
{
        if (snd_BUG_ON(!plugin || !src_channels || !dst_channels))
                return -ENXIO;
        if (frames == 0)
                return 0;
#ifdef CONFIG_SND_DEBUG
        {
                unsigned int channel;
                for (channel = 0; channel < plugin->src_format.channels; channel++) {
                        if (snd_BUG_ON(src_channels[channel].area.first % 8 ||
                                       src_channels[channel].area.step % 8))
                                return -ENXIO;
                        if (snd_BUG_ON(dst_channels[channel].area.first % 8 ||
                                       dst_channels[channel].area.step % 8))
                                return -ENXIO;
                }
        }
#endif
        if (frames > dst_channels[0].frames)
                frames = dst_channels[0].frames;
        convert(plugin, src_channels, dst_channels, frames);
        return frames;
}

static void init_data(struct linear_priv *data,
                      snd_pcm_format_t src_format, snd_pcm_format_t dst_format)
{
        int src_le, dst_le, src_bytes, dst_bytes;

        src_bytes = snd_pcm_format_width(src_format) / 8;
        dst_bytes = snd_pcm_format_width(dst_format) / 8;
        src_le = snd_pcm_format_little_endian(src_format) > 0;
        dst_le = snd_pcm_format_little_endian(dst_format) > 0;

        data->dst_bytes = dst_bytes;
        data->cvt_endian = src_le != dst_le;
        data->copy_bytes = src_bytes < dst_bytes ? src_bytes : dst_bytes;
        if (src_le) {
                data->copy_ofs = 4 - data->copy_bytes;
                data->src_ofs = src_bytes - data->copy_bytes;
        } else
                data->src_ofs = snd_pcm_format_physical_width(src_format) / 8 -
                        src_bytes;
        if (dst_le)
                data->dst_ofs = 4 - data->dst_bytes;
        else
                data->dst_ofs = snd_pcm_format_physical_width(dst_format) / 8 -
                        dst_bytes;
        if (snd_pcm_format_signed(src_format) !=
            snd_pcm_format_signed(dst_format)) {
                if (dst_le)
                        data->flip = (__force u32)cpu_to_le32(0x80000000);
                else
                        data->flip = (__force u32)cpu_to_be32(0x80000000);
        }
}

int snd_pcm_plugin_build_linear(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)
{
        int err;
        struct linear_priv *data;
        struct snd_pcm_plugin *plugin;

        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->channels != dst_format->channels))
                return -ENXIO;
        if (snd_BUG_ON(!snd_pcm_format_linear(src_format->format) ||
                       !snd_pcm_format_linear(dst_format->format)))
                return -ENXIO;

        err = snd_pcm_plugin_build(plug, "linear format conversion",
                                   src_format, dst_format,
                                   sizeof(struct linear_priv), &plugin);
        if (err < 0)
                return err;
        data = (struct linear_priv *)plugin->extra_data;
        init_data(data, src_format->format, dst_format->format);
        plugin->transfer = linear_transfer;
        *r_plugin = plugin;
        return 0;
}