pcm_plugin.c

LINUX 2.6.17.4的源码

	case SNDRV_PCM_STREAM_CAPTURE:
		dstformat.format = params_format(params);
		dstformat.rate = params_rate(params);
		dstformat.channels = params_channels(params);
		srcformat.format = params_format(slave_params);
		srcformat.rate = params_rate(slave_params);
		srcformat.channels = params_channels(slave_params);
		src_access = (slave_interleaved ? SNDRV_PCM_ACCESS_RW_INTERLEAVED :
						  SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
		dst_access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
		break;
	default:
		snd_BUG();
		return -EINVAL;
	}
	tmpformat = srcformat;
		
	pdprintf("srcformat: format=%i, rate=%i, channels=%i\n", 
		 srcformat.format,
		 srcformat.rate,
		 srcformat.channels);
	pdprintf("dstformat: format=%i, rate=%i, channels=%i\n", 
		 dstformat.format,
		 dstformat.rate,
		 dstformat.channels);

	/* Format change (linearization) */
	if (! rate_match(srcformat.rate, dstformat.rate) &&
	    ! snd_pcm_format_linear(srcformat.format)) {
		if (srcformat.format != SNDRV_PCM_FORMAT_MU_LAW)
			return -EINVAL;
		tmpformat.format = SNDRV_PCM_FORMAT_S16;
		err = snd_pcm_plugin_build_mulaw(plug,
						 &srcformat, &tmpformat,
						 &plugin);
		if (err < 0)
			return err;
		err = snd_pcm_plugin_append(plugin);
		if (err < 0) {
			snd_pcm_plugin_free(plugin);
			return err;
		}
		srcformat = tmpformat;
		src_access = dst_access;
	}

	/* channels reduction */
	if (srcformat.channels > dstformat.channels) {
		tmpformat.channels = dstformat.channels;
		err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
		pdprintf("channels reduction: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, err);
		if (err < 0)
			return err;
		err = snd_pcm_plugin_append(plugin);
		if (err < 0) {
			snd_pcm_plugin_free(plugin);
			return err;
		}
		srcformat = tmpformat;
		src_access = dst_access;
	}

	/* rate resampling */
	if (!rate_match(srcformat.rate, dstformat.rate)) {
		if (srcformat.format != SNDRV_PCM_FORMAT_S16) {
			/* convert to S16 for resampling */
			tmpformat.format = SNDRV_PCM_FORMAT_S16;
			err = snd_pcm_plugin_build_linear(plug,
							  &srcformat, &tmpformat,
							  &plugin);
			if (err < 0)
				return err;
			err = snd_pcm_plugin_append(plugin);
			if (err < 0) {
				snd_pcm_plugin_free(plugin);
				return err;
			}
			srcformat = tmpformat;
			src_access = dst_access;
		}
		tmpformat.rate = dstformat.rate;
        	err = snd_pcm_plugin_build_rate(plug,
        					&srcformat, &tmpformat,
						&plugin);
		pdprintf("rate down resampling: src=%i, dst=%i returns %i\n", srcformat.rate, tmpformat.rate, err);
		if (err < 0)
			return err;
		err = snd_pcm_plugin_append(plugin);
		if (err < 0) {
			snd_pcm_plugin_free(plugin);
			return err;
		}
		srcformat = tmpformat;
		src_access = dst_access;
        }

	/* format change */
	if (srcformat.format != dstformat.format) {
		tmpformat.format = dstformat.format;
		if (srcformat.format == SNDRV_PCM_FORMAT_MU_LAW ||
		    tmpformat.format == SNDRV_PCM_FORMAT_MU_LAW) {
			err = snd_pcm_plugin_build_mulaw(plug,
							 &srcformat, &tmpformat,
							 &plugin);
		}
		else if (snd_pcm_format_linear(srcformat.format) &&
			 snd_pcm_format_linear(tmpformat.format)) {
			err = snd_pcm_plugin_build_linear(plug,
							  &srcformat, &tmpformat,
							  &plugin);
		}
		else
			return -EINVAL;
		pdprintf("format change: src=%i, dst=%i returns %i\n", srcformat.format, tmpformat.format, err);
		if (err < 0)
			return err;
		err = snd_pcm_plugin_append(plugin);
		if (err < 0) {
			snd_pcm_plugin_free(plugin);
			return err;
		}
		srcformat = tmpformat;
		src_access = dst_access;
	}

	/* channels extension */
	if (srcformat.channels < dstformat.channels) {
		tmpformat.channels = dstformat.channels;
		err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
		pdprintf("channels extension: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, err);
		if (err < 0)
			return err;
		err = snd_pcm_plugin_append(plugin);
		if (err < 0) {
			snd_pcm_plugin_free(plugin);
			return err;
		}
		srcformat = tmpformat;
		src_access = dst_access;
	}

	/* de-interleave */
	if (src_access != dst_access) {
		err = snd_pcm_plugin_build_copy(plug,
						&srcformat,
						&tmpformat,
						&plugin);
		pdprintf("interleave change (copy: returns %i)\n", err);
		if (err < 0)
			return err;
		err = snd_pcm_plugin_append(plugin);
		if (err < 0) {
			snd_pcm_plugin_free(plugin);
			return err;
		}
	}

	return 0;
}

snd_pcm_sframes_t snd_pcm_plug_client_channels_buf(struct snd_pcm_substream *plug,
					 char *buf,
					 snd_pcm_uframes_t count,
					 struct snd_pcm_plugin_channel **channels)
{
	struct snd_pcm_plugin *plugin;
	struct snd_pcm_plugin_channel *v;
	struct snd_pcm_plugin_format *format;
	int width, nchannels, channel;
	int stream = snd_pcm_plug_stream(plug);

	snd_assert(buf != NULL, return -ENXIO);
	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
		plugin = snd_pcm_plug_first(plug);
		format = &plugin->src_format;
	} else {
		plugin = snd_pcm_plug_last(plug);
		format = &plugin->dst_format;
	}
	v = plugin->buf_channels;
	*channels = v;
	if ((width = snd_pcm_format_physical_width(format->format)) < 0)
		return width;
	nchannels = format->channels;
	snd_assert(plugin->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED || format->channels <= 1, return -ENXIO);
	for (channel = 0; channel < nchannels; channel++, v++) {
		v->frames = count;
		v->enabled = 1;
		v->wanted = (stream == SNDRV_PCM_STREAM_CAPTURE);
		v->area.addr = buf;
		v->area.first = channel * width;
		v->area.step = nchannels * width;
	}
	return count;
}

snd_pcm_sframes_t snd_pcm_plug_write_transfer(struct snd_pcm_substream *plug, struct snd_pcm_plugin_channel *src_channels, snd_pcm_uframes_t size)
{
	struct snd_pcm_plugin *plugin, *next;
	struct snd_pcm_plugin_channel *dst_channels;
	int err;
	snd_pcm_sframes_t frames = size;

	plugin = snd_pcm_plug_first(plug);
	while (plugin && frames > 0) {
		if ((next = plugin->next) != NULL) {
			snd_pcm_sframes_t frames1 = frames;
			if (plugin->dst_frames)
				frames1 = plugin->dst_frames(plugin, frames);
			if ((err = next->client_channels(next, frames1, &dst_channels)) < 0) {
				return err;
			}
			if (err != frames1) {
				frames = err;
				if (plugin->src_frames)
					frames = plugin->src_frames(plugin, frames1);
			}
		} else
			dst_channels = NULL;
		pdprintf("write plugin: %s, %li\n", plugin->name, frames);
		if ((frames = plugin->transfer(plugin, src_channels, dst_channels, frames)) < 0)
			return frames;
		src_channels = dst_channels;
		plugin = next;
	}
	return snd_pcm_plug_client_size(plug, frames);
}

snd_pcm_sframes_t snd_pcm_plug_read_transfer(struct snd_pcm_substream *plug, struct snd_pcm_plugin_channel *dst_channels_final, snd_pcm_uframes_t size)
{
	struct snd_pcm_plugin *plugin, *next;
	struct snd_pcm_plugin_channel *src_channels, *dst_channels;
	snd_pcm_sframes_t frames = size;
	int err;

	frames = snd_pcm_plug_slave_size(plug, frames);
	if (frames < 0)
		return frames;

	src_channels = NULL;
	plugin = snd_pcm_plug_first(plug);
	while (plugin && frames > 0) {
		if ((next = plugin->next) != NULL) {
			if ((err = plugin->client_channels(plugin, frames, &dst_channels)) < 0) {
				return err;
			}
			frames = err;
		} else {
			dst_channels = dst_channels_final;
		}
		pdprintf("read plugin: %s, %li\n", plugin->name, frames);
		if ((frames = plugin->transfer(plugin, src_channels, dst_channels, frames)) < 0)
			return frames;
		plugin = next;
		src_channels = dst_channels;
	}
	return frames;
}

int snd_pcm_area_silence(const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
			 size_t samples, int format)
{
	/* FIXME: sub byte resolution and odd dst_offset */
	unsigned char *dst;
	unsigned int dst_step;
	int width;
	const unsigned char *silence;
	if (!dst_area->addr)
		return 0;
	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
	width = snd_pcm_format_physical_width(format);
	if (width <= 0)
		return -EINVAL;
	if (dst_area->step == (unsigned int) width && width >= 8)
		return snd_pcm_format_set_silence(format, dst, samples);
	silence = snd_pcm_format_silence_64(format);
	if (! silence)
		return -EINVAL;
	dst_step = dst_area->step / 8;
	if (width == 4) {
		/* Ima ADPCM */
		int dstbit = dst_area->first % 8;
		int dstbit_step = dst_area->step % 8;
		while (samples-- > 0) {
			if (dstbit)
				*dst &= 0xf0;
			else
				*dst &= 0x0f;
			dst += dst_step;
			dstbit += dstbit_step;
			if (dstbit == 8) {
				dst++;
				dstbit = 0;
			}
		}
	} else {
		width /= 8;
		while (samples-- > 0) {
			memcpy(dst, silence, width);
			dst += dst_step;
		}
	}
	return 0;
}

int snd_pcm_area_copy(const struct snd_pcm_channel_area *src_area, size_t src_offset,
		      const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
		      size_t samples, int format)
{
	/* FIXME: sub byte resolution and odd dst_offset */
	char *src, *dst;
	int width;
	int src_step, dst_step;
	src = src_area->addr + (src_area->first + src_area->step * src_offset) / 8;
	if (!src_area->addr)
		return snd_pcm_area_silence(dst_area, dst_offset, samples, format);
	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
	if (!dst_area->addr)
		return 0;
	width = snd_pcm_format_physical_width(format);
	if (width <= 0)
		return -EINVAL;
	if (src_area->step == (unsigned int) width &&
	    dst_area->step == (unsigned int) width && width >= 8) {
		size_t bytes = samples * width / 8;
		memcpy(dst, src, bytes);
		return 0;
	}
	src_step = src_area->step / 8;
	dst_step = dst_area->step / 8;
	if (width == 4) {
		/* Ima ADPCM */
		int srcbit = src_area->first % 8;
		int srcbit_step = src_area->step % 8;
		int dstbit = dst_area->first % 8;
		int dstbit_step = dst_area->step % 8;
		while (samples-- > 0) {
			unsigned char srcval;
			if (srcbit)
				srcval = *src & 0x0f;
			else
				srcval = (*src & 0xf0) >> 4;
			if (dstbit)
				*dst = (*dst & 0xf0) | srcval;
			else
				*dst = (*dst & 0x0f) | (srcval << 4);
			src += src_step;
			srcbit += srcbit_step;
			if (srcbit == 8) {
				src++;
				srcbit = 0;
			}
			dst += dst_step;
			dstbit += dstbit_step;
			if (dstbit == 8) {
				dst++;
				dstbit = 0;
			}
		}
	} else {
		width /= 8;
		while (samples-- > 0) {
			memcpy(dst, src, width);
			src += src_step;
			dst += dst_step;
		}
	}
	return 0;
}

#endif