Power-Programmierung/CD1.mdf/magazine/pcmagazi/1991/08/ballgame.c

Text File | 1991-01-04 | 5KB | 211 lines

[[Code Box]]
[[BALLGAME.C, COMPLETE LISTING, INCLUDE MAGNET LOGO]]



#include <conio.h>
#include <dos.h>

/* The following are the frequencies for each note.  An S following the note
   means that the note is a sharp (#). */
#define S     0.0 /* Silence */
#define C1  261.63
#define CS1 277.18
#define D1  293.66
#define DS1 311.13
#define E1  329.63
#define F1  349.23
#define FS1 369.99
#define G1  392.0
#define GS1 415.3
#define A1  440.0
#define AS1 466.16
#define B1  493.88
#define C2  523.25
#define CS2 554.37
#define D2  587.33
#define DS2 622.25
#define E2  659.26
#define F2  698.46
#define FS2 739.99
#define G2  783.99
#define GS2 830.61
#define A2  880.0
#define AS2 932.33
#define B2  987.77

/* The following are the durations of the notes.  To make the song go faster,
   make the definition of E smaller.  To make the song go slower, make the
   definition of E larger.  A P in the second position of the name means that
   this note is half again as large as the one preceding it. */
#define E  0.125    // Eighth note
#define EP (E*1.5)  // dotted 8th
#define Q  (E*2.0)  // quarter note
#define QP (E*3.0)  // dotted quarter
#define H  (Q*2.0)  // half note
#define HP (Q*3.0)  // dotted half
#define W  (H*2.0)  // whole note
#define WP (H*3.0)  // dotted whole

/* The following define the duration of each note (or conversely, the amount
   of silence between notes. */
#define LEGATO  1.0
#define NORMAL  0.875
#define STACCATO 0.75

/* Changing this definition changes the duration of the notes for the entire
   song. */
#define NOTE_DUR NORMAL

/* How much must we speed up the timer.  The value works fine for the tempo
   I've defined here.  If you play a faster song, you might consider
   increasing this value. */
#define CLOCK_INC 4

#define NUM_NOTES 61
static double notes[NUM_NOTES] =
    {
C1, C2, A1, G1, E1, G1, D1,
C1, C2, A1, G1, E1, G1, GS1,
A1, GS1, A1, E1, F1, G1, A1, F1, D1,
A1, A1, A1, B1, C2, D2, B1, A1, G1, F1, D1,
C1, C2, A1, G1, E1, G1, D1,
C1, D1, E1, F1, G1, A1, A1, B1,
C2, C2, C2, B1, A1, G1, FS1, G1, A1, B1, C2
    };
static double sizes[NUM_NOTES] =
    {
H, Q, Q, Q, Q, HP, HP,
H, Q, Q, Q, Q, W, Q,
Q, Q, Q, Q, Q, Q, H, Q, HP,
H, Q, Q, Q, Q, Q, Q, Q, Q, Q, Q,
H, Q, Q, Q, Q, HP, HP,
H, Q, Q, Q, Q, W, Q, Q,
HP, HP, Q, Q, Q, Q, Q, Q, HP, HP, W
    };

volatile long click = 0;
void (interrupt far *orig_int)(void);  /* function pointer to the original interrupt
*/

void init_clock(void);
void reset_clock(void);
void sleep(double how_long);
void sound(double freq, double duration);

void main(void)
    {
    int i;

    init_clock();
    for(i = 0; i < NUM_NOTES; i++)
        sound(notes[i], sizes[i]);
    reset_clock();
    }

void interrupt far new_int(void)
    {
    if((++click % CLOCK_INC) == 0)
        (*orig_int)();
    outp(0x20, 0x20);
    }

void init_clock(void)
    {
    /*
         Increase the 8253 timer's channel 0 output by a factor of CLOCK_INC.
    */

    union
        {
        long divisor;
        unsigned char c[2];
        } count;

    /* Install the new interrupt routine. */

    orig_int = _dos_getvect(0x08);
    _dos_setvect(0x08, new_int);

    /* Increase the timer speed. */
    count.divisor = (long)65536 / CLOCK_INC;
    outp(0x43, 0x36);  /* tell 8253 that count is coming */
    outp(0x40, count.c[0]);  /* send low-order byte */
    outp(0x40, count.c[1]);  /* send high-order byte */
    }

void reset_clock(void)
    {
/*
     Return clock to it's original speed.
*/

/* Reinstall the old interrupt routine. */
    _dos_setvect(0x08, orig_int);

    /* Slow down the clock. */
    outp(0x43, 0x36);  /* tell 8253 that count is coming */
    outp(0x40, (char)0);  /* send low-order byte */
    outp(0x40, (char)0);  /* send high-order byte */
    }

void sleep(double how_long)
    {
    long i,
         orig,
         new;

    orig = click;
    i = (long)((how_long * (18.2 * CLOCK_INC)) + orig);
    new = click;
    while(new < i)
        new = click;
    }

void sound(double freq, double duration)
    {
    /*
        Beep the speaker using the specified frequency.
    */

    double off,
           play;
    union
        {
        long divisor;
        unsigned char c[2];
        } count;
    int p;

    play = duration * NOTE_DUR;
    off = duration - play;

    if(freq != S)
        count.divisor = (long)(1193180 / freq);  /* compute the proper count */
    else
        count.divisor = 0;
    outp(0x43, 0xb6);  /* tell 8253 that count is coming */
    outp(0x42, count.c[0]);  /* send low-order byte */
    outp(0x42, count.c[1]);  /* send high-order byte */
    p = inp(0x61);  /* get existing bit pattern */
    if(freq != S)
        outp(0x61, p | 3);  /* turn on bits 0 and 1 */
    else
        outp(0x61, p);

    sleep(play);

    outp(0x61, p);  /* restore original bits to turn off speaker */

    sleep(off);
    }









Figure D: Executing this program will play "Take Me Out to the Ball Game". To play music on a PC the 8253 timer chip must be reprogrammed; BALLGAME causes it to run four times faster than normal. However, it is written so as not to affect the time-of-day clock.