sound/core/oss/copy.c

Source file repositories/reference/linux-study-clean/sound/core/oss/copy.c

File Facts

System
Linux kernel
Corpus path
sound/core/oss/copy.c
Extension
.c
Size
2154 bytes
Lines
78
Domain
Driver Families
Bucket
sound/core
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

if (!src_channels->enabled) {
			if (dst_channels->wanted)
				snd_pcm_area_silence(&dst_channels->area, 0, frames, plugin->dst_format.format);
			dst_channels->enabled = 0;
			continue;
		}
		dst_channels->enabled = 1;
		snd_pcm_area_copy(&src_channels->area, 0, &dst_channels->area, 0, frames, plugin->src_format.format);
		src_channels++;
		dst_channels++;
	}
	return frames;
}

int snd_pcm_plugin_build_copy(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 snd_pcm_plugin *plugin;
	int width;

	if (snd_BUG_ON(!r_plugin))
		return -ENXIO;
	*r_plugin = NULL;

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

	width = snd_pcm_format_physical_width(src_format->format);
	if (snd_BUG_ON(width <= 0))
		return -ENXIO;

	err = snd_pcm_plugin_build(plug, "copy", src_format, dst_format,
				   0, &plugin);
	if (err < 0)
		return err;
	plugin->transfer = copy_transfer;
	*r_plugin = plugin;
	return 0;
}

Annotation

Implementation Notes