;wavdir.asm
FILESPEC equ "comsysex.dat"
SBPORT   equ 220h
.model tiny
.code
.186
org 100h
start:
      call dsp_reset
      jc no_blaster
      mov bl, 0D1h
      call dsp_write
      call open_file
      call hook_int8
      mov bx, 640
      call reprogram_pit
main_loop:
      cmp byte ptr finished_flag, 0
      je main_loop
      mov bx, 0FFFFh
      call reprogram_pit
      call restore_int8
no_blaster:
      ret

buffer_addr     dw      offset buffer
old_int08h      dd      ?
finished_flag   db      0
filename        db      FILESPEC, 0

int08h_handler proc far
      pusha
      cmp  byte ptr cs:finished_flag, 1
      je exit_handler
      mov di, word ptr cs:buffer_addr
      mov bl, 10h
      call dsp_write
      mov  bl, byte ptr cs:[di]
      call dsp_write
      inc di
      cmp di, offset buffer+5420
      jb not_finished
      mov byte ptr cs:finished_flag, 1
not_finished:
      mov word ptr cs:buffer_addr, di
exit_handler:
      mov al, 20h
      out 20h, al
      popa
      iret
int08h_handler endp

dsp_reset proc near
      mov dx, SBPORT+6
      mov al, 1
      out dx, al
      mov cx, 40
dsploop:
      in al, dx
      loop dsploop
      mov al, 0
      out dx, al
      add dx, 8
      mov cx, 100
check_port:
      in al, dx
      and al, 80h
      jz port_not_ready
      sub dx, 4
      in al, dx
      add dx, 4
      cmp al, 0AAh
      je good_reset
port_not_ready:
      loop check_port
bad_reset:
      stc
      ret
good_reset:
      clc
      ret
dsp_reset endp

dsp_write proc near
      mov dx, SBPORT+0Ch
write_loop:
      in al, dx
      and al, 80h
      jnz write_loop
      mov al, bl
      out dx, al
      ret
dsp_write endp

reprogram_pit proc near
      cli
      mov al, 00110110b
      out 43h, al
      mov al, bl
      out 40h, al
      mov al, bh
      out 40h, al
      sti
      ret
reprogram_pit endp

hook_int8 proc near
      mov ax, 3508h
      int 21h
      mov word ptr old_int08h, bx
      mov word ptr old_int08h+2, es
      mov ax, 2508h
      mov dx, offset int08h_handler
      int 21h
      ret
hook_int8 endp

restore_int8 proc near
      mov ax, 2508h
      lds dx, dword ptr old_int08h
      int 21h
      ret
restore_int8 endp

open_file proc near
      mov ax, 3D00h
      mov dx, offset filename
      int 21h
      jc error_exit
      mov bx, ax
      mov ah, 3Fh
      mov cx, 5420
      mov dx, offset buffer
      int 21h
      ret
error_exit:
      mov ah, 9
      mov dx, offset notopenmsg
      int 21h
      int 20h
notopenmsg   db "Ошибка при открытии файла", 0Dh, 0Ah, '$'
open_file endp

buffer:
       end      start

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