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authorisaki <isaki@NetBSD.org>2019-06-10 13:49:39 +0000
committerisaki <isaki@NetBSD.org>2019-06-10 13:49:39 +0000
commit55ca8a4eb6446dc55d515f8a413f59bd2804c824 (patch)
tree9bd39c5abb4b8628683346ef4f1dc1366d99c201 /sys/dev/audio
parent629269264d849bccacda50be7f526517af601f43 (diff)
Use AUDIO_SCALEDOWN() macro rather than seemingly strange ifdefs.
Discussed on source-changes-d.
Diffstat (limited to 'sys/dev/audio')
-rw-r--r--sys/dev/audio/audio.c60
-rw-r--r--sys/dev/audio/audiodef.h8
2 files changed, 34 insertions, 34 deletions
diff --git a/sys/dev/audio/audio.c b/sys/dev/audio/audio.c
index 60d4214590f..13aa990a0f4 100644
--- a/sys/dev/audio/audio.c
+++ b/sys/dev/audio/audio.c
@@ -1,4 +1,4 @@
-/* $NetBSD: audio.c,v 1.15 2019/06/10 13:28:08 isaki Exp $ */
+/* $NetBSD: audio.c,v 1.16 2019/06/10 13:49:39 isaki Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -142,7 +142,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: audio.c,v 1.15 2019/06/10 13:28:08 isaki Exp $");
+__KERNEL_RCSID(0, "$NetBSD: audio.c,v 1.16 2019/06/10 13:49:39 isaki Exp $");
#ifdef _KERNEL_OPT
#include "audio.h"
@@ -458,6 +458,28 @@ audio_track_bufstat(audio_track_t *track, struct audio_track_debugbuf *buf)
#define SPECIFIED(x) ((x) != ~0)
#define SPECIFIED_CH(x) ((x) != (u_char)~0)
+/*
+ * AUDIO_SCALEDOWN()
+ * This macro should be used for audio wave data only.
+ *
+ * The arithmetic shift right (ASR) (in other words, floor()) is good for
+ * this purpose, and will be faster than division on the most platform.
+ * The division (in other words, truncate()) is not so bad alternate for
+ * this purpose, and will be fast enough.
+ * (Using ASR is 1.9 times faster than division on my amd64, and 1.3 times
+ * faster on my m68k. -- isaki 201801.)
+ *
+ * However, the right shift operator ('>>') for negative integer is
+ * "implementation defined" behavior in C (note that it's not "undefined"
+ * behavior). So only if implementation defines '>>' as ASR, we use it.
+ */
+#if defined(__GNUC__)
+/* gcc defines '>>' as ASR. */
+#define AUDIO_SCALEDOWN(value, bits) ((value) >> (bits))
+#else
+#define AUDIO_SCALEDOWN(value, bits) ((value) / (1 << (bits)))
+#endif
+
/* Device timeout in msec */
#define AUDIO_TIMEOUT (3000)
@@ -3200,11 +3222,7 @@ audio_track_chvol(audio_filter_arg_t *arg)
for (ch = 0; ch < channels; ch++) {
aint2_t val;
val = *s++;
-#if defined(AUDIO_USE_C_IMPLEMENTATION_DEFINED_BEHAVIOR) && defined(__GNUC__)
- val = val * ch_volume[ch] >> 8;
-#else
- val = val * ch_volume[ch] / 256;
-#endif
+ val = AUDIO_SCALEDOWN(val * ch_volume[ch], 8);
*d++ = (aint_t)val;
}
}
@@ -3226,11 +3244,7 @@ audio_track_chmix_mixLR(audio_filter_arg_t *arg)
d = arg->dst;
for (i = 0; i < arg->count; i++) {
-#if defined(AUDIO_USE_C_IMPLEMENTATION_DEFINED_BEHAVIOR) && defined(__GNUC__)
- *d++ = (s[0] >> 1) + (s[1] >> 1);
-#else
- *d++ = (s[0] / 2) + (s[1] / 2);
-#endif
+ *d++ = AUDIO_SCALEDOWN(s[0], 1) + AUDIO_SCALEDOWN(s[1], 1);
s += arg->srcfmt->channels;
}
}
@@ -5027,11 +5041,7 @@ audio_pmixer_process(struct audio_softc *sc)
if (vol != 256) {
m = mixer->mixsample;
for (i = 0; i < sample_count; i++) {
-#if defined(AUDIO_USE_C_IMPLEMENTATION_DEFINED_BEHAVIOR) && defined(__GNUC__)
- *m = *m * vol >> 8;
-#else
- *m = *m * vol / 256;
-#endif
+ *m = AUDIO_SCALEDOWN(*m * vol, 8);
m++;
}
}
@@ -5119,11 +5129,9 @@ audio_pmixer_mix_track(audio_trackmixer_t *mixer, audio_track_t *track,
#if defined(AUDIO_SUPPORT_TRACK_VOLUME)
if (track->volume != 256) {
for (i = 0; i < sample_count; i++) {
-#if defined(AUDIO_USE_C_IMPLEMENTATION_DEFINED_BEHAVIOR) && defined(__GNUC__)
- *d++ = ((aint2_t)*s++) * track->volume >> 8;
-#else
- *d++ = ((aint2_t)*s++) * track->volume / 256;
-#endif
+ aint2_t v;
+ v = *s++;
+ *d++ = AUDIO_SCALEDOWN(v * track->volume, 8)
}
} else
#endif
@@ -5137,11 +5145,9 @@ audio_pmixer_mix_track(audio_trackmixer_t *mixer, audio_track_t *track,
#if defined(AUDIO_SUPPORT_TRACK_VOLUME)
if (track->volume != 256) {
for (i = 0; i < sample_count; i++) {
-#if defined(AUDIO_USE_C_IMPLEMENTATION_DEFINED_BEHAVIOR) && defined(__GNUC__)
- *d++ += ((aint2_t)*s++) * track->volume >> 8;
-#else
- *d++ += ((aint2_t)*s++) * track->volume / 256;
-#endif
+ aint2_t v;
+ v = *s++;
+ *d++ += AUDIO_SCALEDOWN(v * track->volume, 8);
}
} else
#endif
diff --git a/sys/dev/audio/audiodef.h b/sys/dev/audio/audiodef.h
index 06ff79ef4c6..438b7177a98 100644
--- a/sys/dev/audio/audiodef.h
+++ b/sys/dev/audio/audiodef.h
@@ -1,4 +1,4 @@
-/* $NetBSD: audiodef.h,v 1.3 2019/05/23 12:20:27 isaki Exp $ */
+/* $NetBSD: audiodef.h,v 1.4 2019/06/10 13:49:39 isaki Exp $ */
/*
* Copyright (C) 2017 Tetsuya Isaki. All rights reserved.
@@ -63,12 +63,6 @@
*/
/* #define AUDIO_SUPPORT_TRACK_VOLUME */
-/*
- * Whether use C language's "implementation defined" behavior (note that
- * it's not "undefined" behavior). It improves performance well.
- */
-#define AUDIO_USE_C_IMPLEMENTATION_DEFINED_BEHAVIOR
-
/* conversion stage */
typedef struct {
audio_ring_t srcbuf;