MIDI: Optimize the new pitch bending code for a small speedup.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@15160 a1c6a512-1295-4272-9138-f99709370657

4 files changed, 27 insertions, 98 deletions

diff --git a/apps/plugins/midi/midiutil.c b/apps/plugins/midi/midiutil.c
index 8cf8ffcde6..92ab8db8d6 100644
--- a/apps/plugins/midi/midiutil.c
+++ b/apps/plugins/midi/midiutil.c
@@ -25,7 +25,10 @@ int chVol[16] IBSS_ATTR;       /* Channel volume                */
 int chPan[16] IBSS_ATTR;       /* Channel panning               */
 int chPat[16] IBSS_ATTR;                  /* Channel patch                 */
 int chPW[16] IBSS_ATTR;                   /* Channel pitch wheel, MSB only */
-int chPBDepth[16] IBSS_ATTR;                   /* Channel pitch wheel, MSB only */
+int chPBDepth[16] IBSS_ATTR;              /* Channel pitch bend depth */
+int chPBNoteOffset[16] IBSS_ATTR;       /* Pre-computed whole semitone offset */
+int chPBFractBend[16] IBSS_ATTR;        /* Fractional bend applied to delta */
+
 
 struct GPatch * gusload(char *);
 struct GPatch * patchSet[128];
diff --git a/apps/plugins/midi/midiutil.h b/apps/plugins/midi/midiutil.h
index 911774440e..30f0009dc7 100644
--- a/apps/plugins/midi/midiutil.h
+++ b/apps/plugins/midi/midiutil.h
@@ -34,8 +34,7 @@
                  mainly because they have to use 44100Hz sample rate */
 #define MAX_VOICES 16
 #else
-#define MAX_VOICES 24 /* Note: 24 midi channels is the minimum general midi
-                         spec implementation */
+#define MAX_VOICES 24 /* Note: 24 midi channels is the minimum general midi spec implementation */
 #endif /* CPU_PP */
 
 #else	/* Simulator requires 44100Hz, and we can afford to use more voices */
@@ -98,19 +97,6 @@ struct MIDIfile
     int numPatches;
 };
 
-/*
-struct SynthObject
-{
-    struct GWaveform * wf;
-    unsigned int delta;
-    unsigned int decay;
-    unsigned int cp;
-    unsigned char state, loopState, loopDir;
-    unsigned char note, vol, ch, isUsed;
-    int curRate, curOffset, targetOffset;
-    unsigned int curPoint;
-};
-*/
 
 struct SynthObject
 {
@@ -161,6 +147,10 @@ extern int chPan[16];       /* Channel panning               */
 extern int chPat[16];       /* Channel patch                 */
 extern int chPW[16];        /* Channel pitch wheel, MSB only */
 extern int chPBDepth[16];   /* Channel pitch bend depth (Controller 6 */
+extern int chPBNoteOffset[16] IBSS_ATTR;       /* Pre-computed whole semitone offset */
+extern int chPBFractBend[16] IBSS_ATTR;        /* Fractional bend applied to delta */
+
+
 
 extern struct GPatch * gusload(char *);
 extern struct GPatch * patchSet[128];
diff --git a/apps/plugins/midi/sequencer.c b/apps/plugins/midi/sequencer.c
index 638c9ba43a..4c9520f91d 100644
--- a/apps/plugins/midi/sequencer.c
+++ b/apps/plugins/midi/sequencer.c
@@ -52,32 +52,19 @@ static inline void setPatch(int ch, int pat)
 }
 
 
+
 /*
- * Pitch Bend table, Computed by
- * for i=0:127, fprintf('%d,', round(2^16*2^((i-64)/384))); end
- * (When typed into Matlab)
- * 16 bit pitch bend table
-*/
-/*
-long pitchTbl[]=
-{
-   58386,58491,58597,58703,58809,58915,59022,59128,59235,59342,59449,59557,
-   59664,59772,59880,59988,60097,60205,60314,60423,60532,60642,60751,60861,
-   60971,61081,61191,61302,61413,61524,61635,61746,61858,61970,62081,62194,
-   62306,62419,62531,62644,62757,62871,62984,63098,63212,63326,63441,63555,
-   63670,63785,63901,64016,64132,64248,64364,64480,64596,64713,64830,64947,
-   65065,65182,65300,65418,65536,65654,65773,65892,66011,66130,66250,66369,
-   66489,66609,66730,66850,66971,67092,67213,67335,67456,67578,67700,67823,
-   67945,68068,68191,68314,68438,68561,68685,68809,68933,69058,69183,69308,
-   69433,69558,69684,69810,69936,70062,70189,70316,70443,70570,70698,70825,
-   70953,71082,71210,71339,71468,71597,71726,71856,71985,72115,72246,72376,
-   72507,72638,72769,72901,73032,73164,73297,73429
-};
-*/
+    This is the new pitch bend table. There are 512 entries.
+    The middle entry is exactly 65536 - no bending.
 
+    The range of the table is one semitone /in either direction/
+    Ie, one semitone from the center.
 
-/* 512 entries here */
-/*
+    Bends beyond this can be achieved by first offsetting the index
+    into the GUS frequency table by the appropriate number of semitones,
+    and then using this table to bend the rest of the way.
+
+    Generated using Matlab code:
     for i=0:512, fprintf('%d,', round(2^16*2^((i-256)/1536))); end
 */
 
@@ -125,57 +112,8 @@ const uint32_t pitchTbl[] ICONST_ATTR={
     68933,68949,68965,68980,68996,69011,69027,69042,69058,69074,69089,69105,
     69120,69136,69152,69167,69183,69198,69214,69230,69245,69261,69276,69292,
     69308,69323,69339,69355,69370,69386,69402,69417,69433
-
 };
 
-/*
-   58386,58412,58439,58465,58491,58518,58544,58571,58597,58624,58650,58676,
-   58703,58729,58756,58782,58809,58836,58862,58889,58915,58942,58968,58995,
-   59022,59048,59075,59102,59128,59155,59182,59208,59235,59262,59289,59315,
-   59342,59369,59396,59423,59449,59476,59503,59530,59557,59584,59611,59638,
-   59664,59691,59718,59745,59772,59799,59826,59853,59880,59907,59934,59961,
-   59988,60015,60043,60070,60097,60124,60151,60178,60205,60233,60260,60287,
-   60314,60341,60369,60396,60423,60450,60478,60505,60532,60560,60587,60614,
-   60642,60669,60696,60724,60751,60779,60806,60833,60861,60888,60916,60943,
-   60971,60998,61026,61054,61081,61109,61136,61164,61191,61219,61247,61274,
-   61302,61330,61357,61385,61413,61440,61468,61496,61524,61551,61579,61607,
-   61635,61663,61690,61718,61746,61774,61802,61830,61858,61886,61914,61942,
-   61970,61997,62025,62053,62081,62109,62138,62166,62194,62222,62250,62278,
-   62306,62334,62362,62390,62419,62447,62475,62503,62531,62560,62588,62616,
-   62644,62673,62701,62729,62757,62786,62814,62843,62871,62899,62928,62956,
-   62984,63013,63041,63070,63098,63127,63155,63184,63212,63241,63269,63298,
-   63326,63355,63384,63412,63441,63470,63498,63527,63555,63584,63613,63642,
-   63670,63699,63728,63757,63785,63814,63843,63872,63901,63929,63958,63987,
-   64016,64045,64074,64103,64132,64161,64190,64219,64248,64277,64306,64335,
-   64364,64393,64422,64451,64480,64509,64538,64567,64596,64626,64655,64684,
-   64713,64742,64772,64801,64830,64859,64889,64918,64947,64976,65006,65035,
-   65065,65094,65123,65153,65182,65211,65241,65270,65300,65329,65359,65388,
-   65418,65447,65477,65506,65536,65566,65595,65625,65654,65684,65714,65743,
-   65773,65803,65832,65862,65892,65922,65951,65981,66011,66041,66071,66100,
-   66130,66160,66190,66220,66250,66280,66309,66339,66369,66399,66429,66459,
-   66489,66519,66549,66579,66609,66639,66670,66700,66730,66760,66790,66820,
-   66850,66880,66911,66941,66971,67001,67032,67062,67092,67122,67153,67183,
-   67213,67244,67274,67304,67335,67365,67395,67426,67456,67487,67517,67548,
-   67578,67609,67639,67670,67700,67731,67761,67792,67823,67853,67884,67915,
-   67945,67976,68007,68037,68068,68099,68129,68160,68191,68222,68252,68283,
-   68314,68345,68376,68407,68438,68468,68499,68530,68561,68592,68623,68654,
-   68685,68716,68747,68778,68809,68840,68871,68902,68933,68965,68996,69027,
-   69058,69089,69120,69152,69183,69214,69245,69276,69308,69339,69370,69402,
-   69433,69464,69496,69527,69558,69590,69621,69653,69684,69716,69747,69778,
-   69810,69841,69873,69905,69936,69968,69999,70031,70062,70094,70126,70157,
-   70189,70221,70252,70284,70316,70348,70379,70411,70443,70475,70507,70538,
-   70570,70602,70634,70666,70698,70730,70762,70793,70825,70857,70889,70921,
-   70953,70985,71017,71049,71082,71114,71146,71178,71210,71242,71274,71306,
-   71339,71371,71403,71435,71468,71500,71532,71564,71597,71629,71661,71694,
-   71726,71758,71791,71823,71856,71888,71920,71953,71985,72018,72050,72083,
-   72115,72148,72181,72213,72246,72278,72311,72344,72376,72409,72442,72474,
-   72507,72540,72573,72605,72638,72671,72704,72736,72769,72802,72835,72868,
-   72901,72934,72967,72999,73032,73065,73098,73131,73164,73197,73230,73264,
-   73297,73330,73363,73396,73429,73462,73495,73528
-};*/
-
-
-
 
 static void findDelta(struct SynthObject * so, int ch, int note)
 {
@@ -183,16 +121,8 @@ static void findDelta(struct SynthObject * so, int ch, int note)
     struct GWaveform * wf = patchSet[chPat[ch]]->waveforms[patchSet[chPat[ch]]->noteTable[note]];
     so->wf=wf;
     unsigned int delta= 0;
-
-    int totalBend = (chPW[ch]-256) * chPBDepth[ch];
-
-    int noteOffset = totalBend >> 8;
-
-    int pitchOffset = totalBend - (noteOffset<<8);
-
-
-    delta = (((gustable[note+noteOffset]<<FRACTSIZE) / (wf->rootFreq)) * wf->sampRate / (SAMPLE_RATE));
-    delta = (delta * pitchTbl[pitchOffset+256])>> 16;
+    delta = (((gustable[note+chPBNoteOffset[ch]]<<FRACTSIZE) / (wf->rootFreq)) * wf->sampRate / (SAMPLE_RATE));
+    delta = (delta * chPBFractBend[ch])>> 16;
 
     so->delta = delta;
 }
@@ -201,6 +131,10 @@ static inline void setPW(int ch, int msb, int lsb)
 {
     chPW[ch] = msb<<2|lsb>>5;
 
+    int totalBend = (chPW[ch]-256) * chPBDepth[ch];
+    chPBNoteOffset[ch] = totalBend >> 8;
+    chPBFractBend[ch] = pitchTbl[(totalBend & 0xFF) + 256];
+
     int a=0;
     for(a = 0; a<MAX_VOICES; a++)
     {
diff --git a/apps/plugins/midi/synth.c b/apps/plugins/midi/synth.c
index f0fa93d60e..9ec5580310 100644
--- a/apps/plugins/midi/synth.c
+++ b/apps/plugins/midi/synth.c
@@ -66,6 +66,8 @@ int initSynth(struct MIDIfile * mf, char * filename, char * drumConfig)
         chPat[a]=0;              /* Ac Gr Piano                     */
         chPW[a]=256;             /* .. not .. bent ?                */
         chPBDepth[a]=2;          /* Default bend value is 2 */
+        chPBNoteOffset[a]=0;     /* No offset */
+        chPBFractBend[a]=65536; /* Center.. no bend */
     }
     for(a=0; a<128; a++)
     {