#include <stdio.h>
#include <stdlib.h>
typedef unsigned int ui;
char * oc, // Running cursor in buffer for collecting output
   * oe, // End of buffer
   * bb; // Befinning of buffer
// Routine ex is just an easy way out.
int ex(int d){printf("Bye %d\n", d); exit(4);}
// Deposit character in buff if there is room.
void pc(char x){if(oc==oe) ex(1); *(oc++) = x;}
// Deposit string.
void ps(char * s){while(*s) pc(*(s++));}
// Deposit binary number v in c bytes.
void pn(int c, ui v){if(c) {pn(c-1, v>>8); pc(v&255);}}
// Next two routines for depositing variable length binary numbers.
void pvlr(ui n){if(n > 127) pvlr(n>>7); pc(0x80 | n&127);}
void pvl(ui n){if(n > 127) pvlr(n>>7); pc(n&127);}
// Ensure a note down for channel 1 as running status.
static char cst=0;
static void e9(){if(cst != 9)
{pc(0x90); cst=9;}}
// Play note n for duration d.
void n(int n, int d)
  {pvl(0); // Emit dt.
  e9(); // Emit status byte if not already running.
  pc(n); // Emit note value.
  pc(64); // Standard loundess
  pvl(d*120); // dt for note duration
  pc(n); // Which note to stop
  pc(0); // loudness=0 means to stop
  }
int main(){
char * suspense; // Remember where to fill in track length.
// Get a buffer for output.
{int sp = 1000000; bb=oc = (char*)malloc(sp); if(!oc) ex(2); oe = oc+sp;}
ps("MThd"); pn(4, 6); // MIDI file header and length of next three fields.
pn(2, 1); // Format 1 file
pn(2, 1); // Just one track
pn(2, 240); // 240 ticks per quarter note.
// Introduce the music track and remember where to put its length.
ps("MTrk"); suspense = oc; pn(4, 0);
// The music:
pvl(0); pc(0xC0); pc(6); cst=12;// change voice
n(60,2); n(62,2); n(64,2); n(60,2);
n(60,2); n(62,2); n(64,2); n(60,2);
n(64,2); n(65,2); n(67,4);
n(64,2); n(65,2); n(67,4);
n(67,1); n(69,1); n(67,1); n(65,1); n(64,2); n(60,2);
n(67,1); n(69,1); n(67,1); n(65,1); n(64,2); n(60,2);
n(60,2); n(55,2); n(60,4);
n(60,2); n(55,2); n(60,4);
// The "end of track" meta-event.
pvl(0); pc(0xFF); pc(47); pvl(0);
// Fill in the now known track length.
{char*t = oc; oc = suspense; pn(4, t-(oc+4)); oc = t;}
// Next three lines: copy the buffer into the file.
{FILE * out = fopen("song.midi", "w");
{char * c; for(c = bb; c < oc; ++c) putc(*c, out);}
fclose(out);}
// release buffer.
free(bb); 
return 0;}