Optimisation of the midi player, reducing the number of multiplications and memory accesses inside a very frequently executed loop, also does shifting of the whole sample when synthing is done which improves accurracy slightly, ~10% fewer buffer misses
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@14983 a1c6a512-1295-4272-9138-f99709370657
diff --git a/apps/plugins/midi/midiutil.c b/apps/plugins/midi/midiutil.c
index 7cb128f..aba56c5 100644
--- a/apps/plugins/midi/midiutil.c
+++ b/apps/plugins/midi/midiutil.c
@@ -22,8 +22,7 @@
extern struct plugin_api * rb;
int chVol[16] IBSS_ATTR; /* Channel volume */
-int chPanLeft[16] IBSS_ATTR; /* Channel panning */
-int chPanRight[16] IBSS_ATTR;
+int chPan[16] IBSS_ATTR; /* Channel panning */
int chPat[16] IBSS_ATTR; /* Channel patch */
int chPW[16] IBSS_ATTR; /* Channel pitch wheel, MSB only */
diff --git a/apps/plugins/midi/midiutil.h b/apps/plugins/midi/midiutil.h
index 6968c83..3604f42 100644
--- a/apps/plugins/midi/midiutil.h
+++ b/apps/plugins/midi/midiutil.h
@@ -152,8 +152,7 @@
extern struct SynthObject voices[MAX_VOICES];
extern int chVol[16]; /* Channel volume */
-extern int chPanLeft[16]; /* Channel panning */
-extern int chPanRight[16];
+extern int chPan[16]; /* Channel panning */
extern int chPat[16]; /* Channel patch */
extern int chPW[16]; /* Channel pitch wheel, MSB only */
diff --git a/apps/plugins/midi/sequencer.c b/apps/plugins/midi/sequencer.c
index 82da3ef..1a00c07 100644
--- a/apps/plugins/midi/sequencer.c
+++ b/apps/plugins/midi/sequencer.c
@@ -46,15 +46,6 @@
setVolScale(a);
}
-static inline void setPan(int ch, int pan)
-{
-// printf("\npanning[%d] %d ==> %d", ch, chPanRight[ch], pan);
-
- chPanLeft[ch]=128-pan;
- chPanRight[ch]=pan;
-}
-
-
static inline void setPatch(int ch, int pat)
{
chPat[ch]=pat;
@@ -286,7 +277,7 @@
}
case CTRL_PANNING:
{
- setPan((status_low), d2);
+ chPan[status_low]=d2;
return;
}
}
diff --git a/apps/plugins/midi/synth.c b/apps/plugins/midi/synth.c
index 4936afb..322d0f7 100644
--- a/apps/plugins/midi/synth.c
+++ b/apps/plugins/midi/synth.c
@@ -62,10 +62,9 @@
for(a=0; a<16; a++)
{
chVol[a]=100; /* Default, not quite full blast.. */
- chPanLeft[a]=64; /* Center */
- chPanRight[a]=64; /* Center */
+ chPan[a]=64; /* Center */
chPat[a]=0; /* Ac Gr Piano */
- chPW[a]=256; /* .. not .. bent ? */
+ chPW[a]=256; /* .. not .. bent ? */
}
for(a=0; a<128; a++)
{
diff --git a/apps/plugins/midi/synth.h b/apps/plugins/midi/synth.h
index 223b597..2b7187e 100644
--- a/apps/plugins/midi/synth.h
+++ b/apps/plugins/midi/synth.h
@@ -25,7 +25,7 @@
int i;
register int dL=0;
register int dR=0;
- register short sample = 0;
+ register int sample = 0;
register struct SynthObject *voicept=voices;
for(i=MAX_VOICES/2; i > 0; i--)
@@ -33,15 +33,17 @@
if(voicept->isUsed==1)
{
sample = synthVoice(voicept);
- dL += (sample*chPanLeft[voicept->ch])>>7;
- dR += (sample*chPanRight[voicept->ch])>>7;
+ dL += sample;
+ sample *= chPan[voicept->ch];
+ dR += sample;
}
voicept++;
if(voicept->isUsed==1)
{
sample = synthVoice(voicept);
- dL += (sample*chPanLeft[voicept->ch])>>7;
- dR += (sample*chPanRight[voicept->ch])>>7;
+ dL += sample;
+ sample *= chPan[voicept->ch];
+ dR += sample;
}
voicept++;
}
@@ -51,19 +53,22 @@
if(voicept->isUsed==1)
{
sample = synthVoice(voicept);
- dL += (sample*chPanLeft[voicept->ch])>>7;
- dR += (sample*chPanRight[voicept->ch])>>7;
+ dL += sample;
+ sample *= chPan[voicept->ch];
+ dR += sample;
}
voicept++;
}
- *mixL=dL;
- *mixR=dR;
+ dL = (dL << 7) - dR;
+
+ *mixL=dL >> 7;
+ *mixR=dR >> 7;
/* TODO: Automatic Gain Control, anyone? */
/* Or, should this be implemented on the DSP's output volume instead? */
- return; /* No more ghetto lowpass filter.. linear intrpolation works well. */
+ return; /* No more ghetto lowpass filter. Linear interpolation works well. */
}
static inline struct Event * getEvent(struct Track * tr, int evNum)