DOSSEG
      .MODEL SMALL
      .STACK 200h
      .CODE
      .386
      ASSUME CS:@CODE, DS:@CODE
      Ideal

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OldInt  dd  ?

BaseAddress dw 220h

MixedSeg  dw  ?
SampleSeg dw  ?
SampleOff dw  0

FileName  db  "jamhot.sam",0   ;you need to put your filename here...
SamLength dw  ?

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PROC TurnOffSpeaker NEAR
    mov     al,0d3h         ;turn off speaker
    call    Sendcommand
    ret
ENDP TurnOffSpeaker

    ;al = command
PROC SendCommand NEAR
    push    dx
    push    ax
    mov     dx,[cs:BaseAddress]
    add     dx,0ch
sendcommandloop:
    in      al,dx
    or      al,al
    js      sendcommandloop
    pop     ax
    out     dx,al
    pop     dx
    ret
ENDP SendCommand

PROC TurnOnSpeaker NEAR
    mov     al,0d1h
    call    SendCommand
    ret
ENDP TurnOnSpeaker

    ;input- none 
    ;output al=0 successful
    ;       al=1 unsuccessful
    ;Destroys AX,DX,CX
    ;
PROC DspReset NEAR
    mov     dx,[cs:baseaddress]
    add     dx,06h
    mov     al,1
    out     dx,al
    mov     cx,1000
    push    di
    rep     lodsb         ;wait for at least 3µS
    pop     di
    xor     al,al
    out     dx,al

    add     dx,8          ;check status (22eh)
    mov     cx,12000
waitforstat:
    in      al,dx
    dec     cx
    je      errorstat
    or      al,al
    js      WaitForStat

    mov     cx,10000
    sub     dx,4          ;(22ah)      
waitforstat2:
    in      al,dx
    dec     cx
    je      errorstat
    cmp     al,0aah
    jne     waitforstat2
    mov     al,0
    ret
errorstat:
    mov     al,1
    ret
ENDP DspReset

PROC SetUpInterrupt NEAR
    pusha
    push    ds

    mov   ax,0
    mov   ds,ax
    mov   bx,8*4                  ;interrupt 8
    mov   ax,[ds:bx]
    mov   [Word LOW  cs:OldInt],ax
    mov   ax,[ds:bx+2]
    mov   [Word HIGH cs:OldInt],ax

    cli
    mov   [Word ds:bx],offset TimerInt
    mov   [ds:bx+2],cs

    mov   al,36h
    out   43h,al                  ; timer program

    mov   ax,1193180/8000         ; # of ticks between interrupts
                                  ; Clock Freq / HZ
    out   40h,al
    mov   al,ah
    out   40h,al
    sti

    pop     ds
    popa
    ret
ENDP SetUpInterrupt
  
PROC RemoveInterrupt NEAR
    pusha
    push    ds
    
    cli
    mov ax,0
    mov ds,ax
    mov bx,8*4
    mov ax,[Word cs:OldInt]
    mov [ds:bx],ax
    mov ax,[Word cs:OldInt+2]
    mov [ds:bx+2],ax
    mov al,36h
    out 43h,al
    xor al,al
    out 40h,al
    out 40h,al
    sti
    
    pop     ds
    popa
    ret
ENDP  RemoveInterrupt

PROC TimerInt FAR
    pusha
    push    fs
    
    mov     fs,[cs:SampleSeg]
    mov     di,[cs:SampleOff]
    
    mov     al,10h + 0b            ;Direct 8-bit DAC command
    call    SendCommand

    mov     al,[fs:di]
    add     al,128            ;change SAM data (-128 to 127) to SB data 0-255
    call    SendCommand
    
    inc     [cs:SampleOff]
    mov     ax,[CS:SamLength]
    cmp     [cs:SampleOff],ax
    jb      @@NotOver
    mov     [cs:SampleOff],0

@@NotOver:
    mov     al,20h      ;acknowledge hardware interrupt
    out     20h,al

    pop     fs
    popa
    iret
ENDP TimerInt

  ; returns -1 if load not successful
PROC  LoadSample NEAR
    pusha
    push    ds

    mov     ax,cs
    mov     ds,ax
    mov     dx,offset FileName
    mov     ax,3D00h        ;open the file
    int     21h
    jc      @@Error

    mov     bx,ax
    xor     dx,dx             ;load at offset 0
    mov     cx,0ffffh         ;read in a whole segments worth
    mov     ds,[cs:SampleSeg]
    mov     ax,3F00h          ; Load in the sample
    int     21h

    mov     [cs:SamLength],ax

    mov     ax,3E00h          ;close the file
    int     21h

    ;*******  HERE'S THE PART WHERE THE SAMPLES ARE MIXED ! *******
    push    es
    mov     es,[cs:MixedSeg]
    mov     cx,[cs:SamLength]
    mov     bp,cx

    mov     di,1500
    mov     si,0
MixLoop:
    
    mov     al,[ds:si]
    sar     al,1        ;divide by 2, cause we're mixing 2 samples together
    mov     [es:si],al

    mov     al,[ds:di]
    sar     al,1
    add     [es:si],al

    inc     si
    inc     di
    cmp     di,bp
    jb      NotExceeded
    mov     di,0
NotExceeded:
    loop    MixLoop

    mov     [cs:SampleSeg],es

    pop     es
    pop     ds
    popa
    xor     ax,ax
    ret

@@Error:
    pop     ds
    popa
    mov     ax,-1
    ret
ENDP  LoadSample

────────────────────────────────────────────────────────────────────────────

START:
    mov   bx,ss
    add   bx,20h            ;put sample right after stack
    mov   [cs:SampleSeg],bx
    add   bx,1000h
    mov   [cs:MixedSeg],bx

    call  LoadSample
    or    al,al
    jne   ByeBye

    call  DspReset
    call  TurnOnSpeaker
    call  SetUpInterrupt    ;starts going after this line

    mov   ah,0
    int   16h               ;wait for a keypress
    
    call  RemoveInterrupt
    call  TurnOffSpeaker

ByeBye:    
    mov   ax,4c00h
    int   21h

END START