C / C++ / MFC

//////////////////////////////////////////////////////////////////////////
// 
// Speaker beep using direct IO
// Source: http://courses.ece.uiuc.edu/ece291/books/labmanual/io-devices-speaker.html
//
//////////////////////////////////////////////////////////////////////////
 
void TD_Hlp_SoundNote(short nNoteIndex, short duration) {
 
#if defined(_X86_)
    int notes[] = { 9121, 8609,
            8126, 7670, 7239, 6833,  6449, 6087,  5746, 5423,
            5119, 4831,  4560,  4304, 4063,  3834, 3619, 3416,
            3224, 3043,  2873, 2711 , 2559, 2415, 2280,  2152, 
            2031,  1917, 1809, 1715,  1612, 1521,  1436, 1355,  
            1292, 1207,  1140 
    };
 
    short note = notes[nNoteIndex];
 
    _asm {
        mov     al, 182;         // Prepare the speaker for the
        out     43h, al;         //  note.
        mov     ax, note;        // Frequency number (in decimal) (was 4560)
                                 //  for middle C.
        out     42h, al;         // Output low byte.
        mov     al, ah;          // Output high byte.
        out     42h, al; 
        in      al, 61h;         // Turn on note (get value from
                                 //  port 61h).
        or      al, 00000011b;   // Set bits 1 and 0.
        out     61h, al;         // Send new value.
        mov     bx, duration;    // Pause for duration of note. (was 25)
pause1:
        mov     cx, 65535;
pause2:
        dec     cx;
        jne     pause2;
        dec     bx;
        jne     pause1;
        in      al, 61h;         // Turn off note (get value from
                                 //  port 61h).
        and     al, 11111100b;   // Reset bits 1 and 0.
        out     61h, al;         // Send new value.
    }
 
#else
#pragma message("TDHlpFns.c: i386 specific speaker code removed")
#endif // defined(i386)