This patch proceeds more abstraction of PCM read/write loop codes.
For both interleaved and non-interleaved transfers, the same copy or
silence transfer code (which is defined as pcm_transfer_f) is used
now. This became possible since we switched to byte size to copy_*
and fill_silence ops argument instead of frames.
And, for both read and write, we can use the same copy function (which
is defined as pcm_copy_f), just depending on whether interleaved or
non-interleaved mode.
The transfer function is determined at the beginning of the loop,
depending on whether the driver gives the specific copy ops or it's
the standard read/write.
Another bonus by this change is that we now guarantee the silencing
behavior when NULL buffer is passed to write helpers. It'll simplify
some codes later.
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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