Path: utzoo!attcan!uunet!aplcen!wb3ffv!ka3ovk!irscscm!mlake
From: mlake@irscscm.UUCP (Marshall Lake)
Newsgroups: comp.sys.atari.st.tech
Subject: Using Timer A to replay a sample
Message-ID: <1990Sep24.122920.15704@irscscm.UUCP>
Date: 24 Sep 90 12:29:20 GMT
Reply-To: mlake@irscscm.UUCP (Marshall Lake)
Organization: Internal Revenue Service, Washington, DC
Lines: 100


I have a programming problem and I'm hoping someone here can help me.

I am attempting to play back a sample via timer A while allowing other
things to go on as it plays.  When the program attempts to start the
actual playback it blows, sometimes displaying 4 bombs and sometimes
6.  I have also tried to place the interrupt code into the main flow
of the program to see what would happen.  The bombs don't occur but
nothing is emitted by the sound chip either.  What am I doing wrong?

The code follows:

#include <osbind.h>
#include <xbios.h>

long *buff_cnt, *buff_end, *sound_chip = 0xff8800, *gi_write = 0xff8802;
char *trumpet_sound;
int snd_value,
    snd_out[1025] = { <table of values same as in other programs
                       that play back samples>  };

do_snd () {
    if (buff_cnt > buff_end)
        return;

    snd_value = (*buff_cnt + 128) * 8;*/
    *sound_chip = snd_out[snd_value];
    *sound_chip = snd_out[snd_value + 4];

    buff_cnt++;
}

play (addr)
char *addr;
{
    buff_cnt = addr;
    buff_end = addr + 58965L;
}

set_snd_chip () {
    *sound_chip = 0;
    *gi_write = 0;
    *sound_chip = 1;
    *gi_write = 0;
    *sound_chip = 2;
    *gi_write = 0;
    *sound_chip = 3;
    *gi_write = 0;
    *sound_chip = 4;
    *gi_write = 0;
    *sound_chip = 5;
    *gi_write = 0;
    *sound_chip = 7;
    *gi_write = 255;
    *sound_chip = 8;
    *gi_write = 0;
    *sound_chip = 9;
    *gi_write = 0;
    *sound_chip = 10;
    *gi_write = 0;
}

main () {
    char *save_ssp;
    int counter, read_handle;

    if ((trumpet_sound = (char *) Malloc (58 * 1024L)) == 0) {
        printf ("\n\n NOT ENOUGH MEMORY \n\n");
        exit ();
    }
    if ((read_handle = Fopen ("trumpet.spl", 0)) < 0) {
        printf ("\n Cannot find trumpet.spl \n");
        exit ();
    }
    Fread (read_handle, 58965L, trumpet_sound);
    Fclose (read_handle);

    buff_cnt = 1L;
    buff_end = 0L;

    Supexec (&set_snd_chip);
    save_ssp = Super (0L);
    Xbtimer (0, 7, 0, &do_snd);

    play (trumpet_sound);

    counter = 0;
    while (1) {
        if (counter == 30000)
            break;
        printf ("counter = %d\n", counter++);
    }

    Xbtimer (0, 0, 0, &do_snd);
    Super (save_ssp);
}
-- 
Marshall Lake
mlake@irscscm.UUCP
...!uunet!media!ka3ovk!irscscm!mlake