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ALSA: tlv: compute TLV_*_ITEM lengths automatically 

Add helper macros with a little bit of preprocessor magic to
automatically compute the length of a TLV item.  This lets us avoid
having to compute this by hand, and will allow to use items that do
not use a fixed length.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Clemens Ladisch 2011-11-20 16:22:24 +01:00 committed by Takashi Iwai
parent 1464189f8c
commit b5b9eb5467
1 changed files with 12 additions and 8 deletions
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20
include/sound/tlv.h
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@ -38,21 +38,26 @@
#define SNDRV_CTL_TLVT_DB_MINMAX 4 /* dB scale with min/max */
#define SNDRV_CTL_TLVT_DB_MINMAX_MUTE 5 /* dB scale with min/max with mute */
#define TLV_ITEM(type, ...) \
(type), TLV_LENGTH(__VA_ARGS__), __VA_ARGS__
#define TLV_LENGTH(...) \
((unsigned int)sizeof((const unsigned int[]) { __VA_ARGS__ }))
#define TLV_DB_SCALE_MASK 0xffff
#define TLV_DB_SCALE_MUTE 0x10000
#define TLV_DB_SCALE_ITEM(min, step, mute) \
SNDRV_CTL_TLVT_DB_SCALE, 2 * sizeof(unsigned int), \
(min), ((step) & TLV_DB_SCALE_MASK) | ((mute) ? TLV_DB_SCALE_MUTE : 0)
TLV_ITEM(SNDRV_CTL_TLVT_DB_SCALE, \
(min), \
((step) & TLV_DB_SCALE_MASK) | \
((mute) ? TLV_DB_SCALE_MUTE : 0))
#define DECLARE_TLV_DB_SCALE(name, min, step, mute) \
unsigned int name[] = { TLV_DB_SCALE_ITEM(min, step, mute) }
/* dB scale specified with min/max values instead of step */
#define TLV_DB_MINMAX_ITEM(min_dB, max_dB) \
SNDRV_CTL_TLVT_DB_MINMAX, 2 * sizeof(unsigned int), \
(min_dB), (max_dB)
TLV_ITEM(SNDRV_CTL_TLVT_DB_MINMAX, (min_dB), (max_dB))
#define TLV_DB_MINMAX_MUTE_ITEM(min_dB, max_dB) \
SNDRV_CTL_TLVT_DB_MINMAX_MUTE, 2 * sizeof(unsigned int), \
(min_dB), (max_dB)
TLV_ITEM(SNDRV_CTL_TLVT_DB_MINMAX_MUTE, (min_dB), (max_dB))
#define DECLARE_TLV_DB_MINMAX(name, min_dB, max_dB) \
unsigned int name[] = { TLV_DB_MINMAX_ITEM(min_dB, max_dB) }
#define DECLARE_TLV_DB_MINMAX_MUTE(name, min_dB, max_dB) \
@ -60,8 +65,7 @@
/* linear volume between min_dB and max_dB (.01dB unit) */
#define TLV_DB_LINEAR_ITEM(min_dB, max_dB) \
SNDRV_CTL_TLVT_DB_LINEAR, 2 * sizeof(unsigned int), \
(min_dB), (max_dB)
TLV_ITEM(SNDRV_CTL_TLVT_DB_LINEAR, (min_dB), (max_dB))
#define DECLARE_TLV_DB_LINEAR(name, min_dB, max_dB) \
unsigned int name[] = { TLV_DB_LINEAR_ITEM(min_dB, max_dB) }