Aren
/
NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Use AUDIO_SCALEDOWN() macro rather than seemingly strange ifdefs. 

Discussed on source-changes-d.
This commit is contained in:
isaki 2019-06-10 13:49:39 +00:00
parent b64d6e1850
commit 4ed2212903
2 changed files with 34 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
sys/dev/audio/audio.c
View File

@ -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

8
sys/dev/audio/audiodef.h
View File

@ -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;