smf.c

   1 /*
   2 orgux - a just-for-fun real time synth
   3 Copyright (C) 2009  Evan Rinehart
   4
   5 This program is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU General Public License
   7 as published by the Free Software Foundation; either version 2
   8 of the License, or (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  18 */
  19
  20 /* smf */
  21
  22 #include <stdio.h>
  23 #include <string.h>
  24
  25 #include "orgux.h"
  26
  27 #define STRING_MAX 256
  28
  29 typedef unsigned char octet;
  30
  31 extern void orgux_seq_append(orgux_state* S, int tick, int type, int chan, int val1, int val2);
  32 extern void orgux_seq_sort(orgux_state* S);
  33
  34 int bytes2short(octet arr[2]){
  35   return (arr[0]<<8) | arr[1];
  36 }
  37
  38 int bytes2int(octet arr[4]){
  39   return (arr[0]<<24) | (arr[1]<<16) | (arr[2]<<8) | arr[3];
  40 }
  41
  42
  43 /* read a bunch of bytes and discard */
  44 void skip_ahead(orgux_reader* src, int count){
  45   const int W = 256;
  46   char buf[W];
  47
  48   int C = count;
  49
  50   while(C > W){
  51     src->read(buf,W,src->ud);
  52     C -= W;
  53   }
  54   src->read(buf,C,src->ud);
  55 }
  56
  57 octet read_one(orgux_reader* src){
  58   octet byte[1];
  59   src->read(byte,1,src->ud);
  60   return byte[0];
  61 }
  62
  63 int get_delta(orgux_reader* src){
  64   octet a = read_one(src);
  65   if(a<0x80){return a;}
  66
  67   octet b = read_one(src);
  68   if(b<0x80){return ((a&0x7f)<<7) | b;}
  69
  70   octet c = read_one(src);
  71   if(c<0x80){return ((a&0x7f)<<14) | ((b&0x7f)<<7) | c;}
  72
  73   octet d = read_one(src);
  74   return ((a&0x7f)<<21) | ((b&0x7f)<<14) | ((c&0x7f)<<7) | d;
  75 }
  76
  77
  78 int orgux_load_song(orgux_state* S, orgux_reader* src){
  79
  80   char buf[16];
  81   char string[STRING_MAX];
  82   int e;
  83   int n;
  84
  85   int loopstart;
  86   int loopend;
  87   int uspq;
  88
  89   /*MThd*/
  90   if(src->read(buf,4,src->ud)<0) return -1;
  91 printf("%x %x %x %x\n",buf[0],buf[1],buf[2],buf[3]);
  92   /*0x00000006*/
  93   if(src->read(buf,4,src->ud)<0) return -1;
  94 printf("%x %x %x %x\n",buf[0],buf[1],buf[2],buf[3]);
  95   /*format type: 0x0000 0x0001 or 0x0002*/
  96   if(src->read(buf,2,src->ud)<0) return -1;
  97 printf("%x %x\n",buf[0],buf[1]);
  98   /*number of tracks*/
  99   if(src->read(buf,2,src->ud)<0) return -1;
 100   int track_count = bytes2short(buf);
 101 printf("%x %x\n",buf[0],buf[1]);
 102 printf("track count = %d\n",track_count);
 103   /* time division */
 104   if(src->read(buf,2,src->ud)<0) return -1;
 105   //code to figure out time division
 106 printf("%x %x\n",buf[0],buf[1]);
 107   for(int i=0; i<track_count; i++){
 108
 109     /*MTrk*/
 110     if(src->read(buf,4,src->ud)<0) return -1;
 111 printf("%x %x %x %x\n",buf[0],buf[1],buf[2],buf[3]);
 112     /* chunk size */
 113     if(src->read(buf,4,src->ud)<0) return -1;
 114     int chunk_size = bytes2int(buf);
 115 printf("%x %x %x %x\n",buf[0],buf[1],buf[2],buf[3]);
 116 printf("chunk size = %d\n",chunk_size);
 117     int tick = 0;
 118     int end_of_track = 0;
 119     int last_type = 0x80;
 120     int last_chan = 0;
 121     while(1){
 122       int delta = get_delta(src);
 123 printf("delta = %d\n",delta);
 124       if(delta < 0) return -1;
 125       tick += delta;
 126
 127       //type and channel
 128       if(src->read(buf,1,src->ud)<0) return -1;
 129       int type = buf[0] & 0xf0;
 130       if(type >= 0x80 && type <= 0xe0){//normal event
 131         last_type = type;
 132         int chan = buf[0] & 0x0f;
 133         last_chan = chan;
 134         if(src->read(buf,2,src->ud)<0) return -1;
 135         int val1 = buf[0];
 136         int val2 = buf[1];
 137 printf("normal %x %x %x\n",type|chan,val1,val2);
 138         orgux_seq_append(S,tick,type,chan,val1,val2);
 139       }
 140       else if(type < 0x80){//running status
 141         int val1 = buf[0];
 142         if(src->read(buf,1,src->ud)<0) return -1;
 143         int val2 = buf[0];
 144 printf("running %x %x %x\n",last_type|last_chan,val1,val2);
 145         orgux_seq_append(S,tick,last_type,last_chan,val1,val2);
 146       }
 147       else if(type == 0xff){//meta event
 148         if(src->read(buf,1,src->ud)<0) return -1;
 149         type = buf[0];
 150 printf("meta event\n");
 151         int len = get_delta(src);
 152         if(len < 0) return -1;
 153
 154         switch(type){
 155           case 0x2f: printf("end of track\n"); end_of_track = 1; break;
 156           case 0x51:printf("tempo change\n");/*tempo*/
 157             if(src->read(buf,3,src->ud)<0) return -1;
 158             uspq = (buf[0]<<16) | (buf[1]<<8) | buf[0];
 159             break;
 160           case 0x58: printf("time sig\n");/*time signature*/
 161             if(src->read(buf,4,src->ud)<0) return -1;
 162             //...
 163             break;
 164           case 0x01: printf("text\n");/*text*/
 165             if(len >= STRING_MAX){skip_ahead(src, len);}
 166             else{
 167               if(src->read(string,len,src->ud)<0) return -1;
 168               string[len] = '\0';
 169               if(strncmp(string,"LoopStart",len)==0){
 170                 loopstart = tick;
 171               }
 172               else if(strncmp(string,"LoopEnd",len)==0){
 173                 loopend = tick;
 174               }
 175             }
 176
 177             break;
 178           default: skip_ahead(src,len); break;
 179         }
 180       }
 181       else{printf("sysex\n");//sysex and such...
 182         int len = get_delta(src);
 183         if(len < 0) return -1;
 184         skip_ahead(src, len);
 185       }
 186
 187       if(end_of_track) break;
 188     }
 189
 190   }
 191
 192   orgux_seq_sort(S);
 193
 194   //orgux_set_tempo();
 195   //orgux_set_loop_positions(S, loopstart, loopend);
 196
 197   return 0;
 198
 199 }
 200
 201
 202 int read_file(unsigned char* buf, int count, void* ud){
 203   FILE* f = (FILE*)ud;
 204   int n = fread(buf, 1, count, f);
 205   if(n < count){return -1;}
 206   return 0;
 207 }
 208
 209 int orgux_load_smf(orgux_state* S, char* filename){
 210   FILE* f = fopen(filename, "r");
 211   if(!f){return -1;}
 212   orgux_reader src;
 213   src.ud = f;
 214   src.read = read_file;
 215 printf("loading midi file\n");
 216   if(orgux_load_song(S, &src) < 0){fclose(f); return -1;}
 217   fclose(f);
 218   return 0;
 219 }