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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

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@14983 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Nils Wallménius 2007-10-04 19:36:42 +00:00
parent cc5b50b231
commit e1940b87b0
5 changed files with 20 additions and 27 deletions
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3
apps/plugins/midi/midiutil.c
View file

@ -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 */

3
apps/plugins/midi/midiutil.h
View file

@ -152,8 +152,7 @@ void * my_malloc(int size);
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 */

11
apps/plugins/midi/sequencer.c
View file

@ -46,15 +46,6 @@ static inline void setVol(int ch, int vol)
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 @@ static void sendEvent(struct Event * ev)
}
case CTRL_PANNING:
{
setPan((status_low), d2);
chPan[status_low]=d2;
return;
}
}

5
apps/plugins/midi/synth.c
View file

@ -62,10 +62,9 @@ int initSynth(struct MIDIfile * mf, char * filename, char * drumConfig)
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++)
{

25
apps/plugins/midi/synth.h
View file

@ -25,7 +25,7 @@ static inline void synthSample(int * mixL, int * mixR)
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 @@ static inline void synthSample(int * mixL, int * mixR)
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 @@ static inline void synthSample(int * mixL, int * mixR)
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)