[alsa-devel] [PATCH] ASoC: rsnd: Calculate DALIGN inversion at run-time

[Geert Uytterhoeven]

There is no need to store the inverted DALIGN values in the table, as
they can easily be calculated at run-time.  This also protects against
the introduction of inconsistencies between normal and inverted values
by a future table modification.

Reorder the two subexpressions in the AND check, to perform the least
expensive check first.

Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
---
Compile-tested only.

Interestingly, this decreases code size on arm64, but increases on arm32
(both gcc version 7.4.0 (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1)).

arm32:

       text	   data	    bss	    dec	    hex	filename
      16186	    276	     84	  16546	   40a2	sound/soc/sh/rcar/core.o.orig
      16194	    276	     84	  16554	   40aa	sound/soc/sh/rcar/core.o

arm64:

       text	   data	    bss	    dec	    hex	filename
      17426	    392	    104	  17922	   4602	sound/soc/sh/rcar/core.o.orig
      17414	    392	    104	  17910	   45f6	sound/soc/sh/rcar/core.o
---
 sound/soc/sh/rcar/core.c | 31 +++++++++++++------------------
 1 file changed, 13 insertions(+), 18 deletions(-)

diff --git a/sound/soc/sh/rcar/core.c b/sound/soc/sh/rcar/core.c
index 399dc6e9bde5b042..d20f03dfdee66643 100644
--- a/sound/soc/sh/rcar/core.c
+++ b/sound/soc/sh/rcar/core.c
@@ -376,20 +376,15 @@ u32 rsnd_get_adinr_bit(struct rsnd_mod *mod, struct rsnd_dai_stream *io)
  */
 u32 rsnd_get_dalign(struct rsnd_mod *mod, struct rsnd_dai_stream *io)
 {
-	static const u32 dalign_values[8][2] = {
-		{0x76543210, 0x67452301},
-		{0x00000032, 0x00000023},
-		{0x00007654, 0x00006745},
-		{0x00000076, 0x00000067},
-		{0xfedcba98, 0xefcdab89},
-		{0x000000ba, 0x000000ab},
-		{0x0000fedc, 0x0000efcd},
-		{0x000000fe, 0x000000ef},
+	static const u32 dalign_values[8] = {
+		0x76543210, 0x00000032, 0x00007654, 0x00000076,
+		0xfedcba98, 0x000000ba, 0x0000fedc, 0x000000fe,
 	};
-	int id = 0, inv;
+	int id = 0;
 	struct rsnd_mod *ssiu = rsnd_io_to_mod_ssiu(io);
 	struct rsnd_mod *target;
 	struct snd_pcm_runtime *runtime = rsnd_io_to_runtime(io);
+	u32 dalign;
 
 	/*
 	 * *Hardware* L/R and *Software* L/R are inverted for 16bit data.
@@ -425,15 +420,15 @@ u32 rsnd_get_dalign(struct rsnd_mod *mod, struct rsnd_dai_stream *io)
 	if (mod == ssiu)
 		id = rsnd_mod_id_sub(mod);
 
-	/* Non target mod or non 16bit needs normal DALIGN */
-	if ((snd_pcm_format_width(runtime->format) != 16) ||
-	    (mod != target))
-		inv = 0;
-	/* Target mod needs inverted DALIGN when 16bit */
-	else
-		inv = 1;
+	dalign = dalign_values[id];
+
+	if (mod == target && snd_pcm_format_width(runtime->format) == 16) {
+		/* Target mod needs inverted DALIGN when 16bit */
+		dalign = (dalign & 0xf0f0f0f0) >> 4 |
+			 (dalign & 0x0f0f0f0f) << 4;
+	}
 
-	return dalign_values[id][inv];
+	return dalign;
 }
 
 u32 rsnd_get_busif_shift(struct rsnd_dai_stream *io, struct rsnd_mod *mod)
-- 
2.17.1