[PATCH 3.2 09/70] ALSA: tlv: compute TLV_*_ITEM lengths automatically

Ben Hutchings
2016-01-18T03:40:18Z

From: Clemens Ladisch <clemens@ladisch.de>

commit b5b9eb546762c4015c67c31364a6ec6f83fd2ada upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
include/sound/tlv.h | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/include/sound/tlv.h b/include/sound/tlv.h
index 7067e2d..137d165 100644
--- a/include/sound/tlv.h
+++ b/include/sound/tlv.h
@@ -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) }