Category : Miscellaneous Language Source Code
Archive   : DIGITIZE.ZIP
Filename : PLAY.ASM

COUNTR EQU 72 ;16572 HZ

TCADRC EQU 43H
TCADRD EQU 40H

TCMODE EQU 34H
TC2MODE EQU 0B8H

PPIADR EQU 61H
NORMPPI EQU 48H

;-------------------------------------------

STK SEGMENT STACK
DW 128 DUP (0)
STK ENDS

;-------------------------------------------

CODE SEGMENT PARA
ASSUME CS:CODE,DS:CODE,SS:STK
ASSUME ES:NOTHING

;-------------------------------------------

FILELEN DW 0
HANDLE DW 0
MSG2 DB 'Disk error',0DH,0AH,24H

;-------------------------------------------

START:

CALL PARSESGL

;set DS and ES

PUSH CS
POP DS
PUSH CS
POP ES

;open the file

MOV DX,OFFSET PARM
MOV AX,3D00H
INT 21H
JNC L1
JMP DSKERR
L1: MOV HANDLE,AX

;read the file

PUSH DS
MOV BX,HANDLE
MOV AX,HIMEM
MOV DS,AX
ASSUME DS:NOTHING
MOV DX,0
MOV CX,0FFFFH
MOV AH,3FH
INT 21H
POP DS
ASSUME DS:CODE
JNC L2
JMP DSKERR
L2: MOV FILELEN,AX

;close the file

MOV BX,HANDLE
MOV AH,3EH
INT 21H

;get vector of timer current timer interrupt

MOV AX,3508H
INT 21H
MOV WORD PTR OLDTMRINT,BX
MOV WORD PTR OLDTMRINT+2,ES

;mask timer interrupt

IN AL,21H
OR AL,01H
OUT 21H,AL

;plug in the local timer interrupt routine

MOV DX,OFFSET TIMERINT
MOV AX,2508H
INT 21H

;rev up timer

MOV AL,TCMODE
OUT TCADRC,AL
MOV AX,COUNTR
OUT TCADRD,AL
MOV AL,AH
OUT TCADRD,AL

;set DS

ASSUME DS:NOTHING
MOV AX,HIMEM
MOV DS,AX

;initialize registers

MOV BP,0
MOV BX,0
MOV CH,[BX]
MOV AH,0
MOV DX,PPIADR

;unmask timer interrupt

IN AL,21H
AND AL,0FEH
OUT 21H,AL
STI

;test for done

TFD:
OR BP,BP
JE TFD

;mask timer interrupt

CLI
IN AL,21H
OR AL,01H
OUT 21H,AL
STI

;fix DS

MOV AX,CS
MOV DS,AX
ASSUME DS:CODE

;fix timer

MOV AL,TCMODE
OUT TCADRC,AL
MOV AL,0
OUT TCADRD,AL
OUT TCADRD,AL

;restore original timer interrupt vector

PUSH DS
LDS DX,CS:OLDTMRINT
MOV AX,2508H
INT 21H
POP DS

;unmask timer interrupt

IN AL,21H
AND AL,0FEH
OUT 21H,AL


;figure out how long the system 18.2 Hz
; timer has been off

MOV AX,COUNTR
SHL AX,1
SHL AX,1
SHL AX,1
MOV CX,FILELEN
MUL CX

;adjust the BIOS time of day to catch up

PUSH ES
MOV AX,40H
MOV ES,AX
MOV BX,6CH
CLI
ADD ES:[BX],DX
ADC WORD PTR ES:[BX+2],0
CMP WORD PTR ES:[BX+2],18H
JB BIOSFIXED
JA WRAP
CMP WORD PTR ES:[BX],0B0H
JB BIOSFIXED
WRAP: SUB WORD PTR ES:[BX],0B0H
SBB WORD PTR ES:[BX+2],18H
BIOSFIXED: STI
POP ES

;exit

MOV AX,4C00H
INT 21H

;disk error message

DSKERR:
MOV AX,CS
MOV DS,AX
MOV DX,OFFSET MSG2
MOV AH,9
INT 21H
MOV AX,4C01H
INT 21H

;-------------------------------------------

;timer interrupt routine

ASSUME DS:NOTHING,ES:NOTHING
ASSUME SS:NOTHING

EVEN

OLDTMRINT DD 0

TIMERINT PROC FAR

OR BP,BP
JNZ TMRINT1

SUB AL,AL
RCL CH,1
RCL AL,1
RCL AL,1
OR AL,NORMPPI
OUT DX,AL

INC AH
CMP AH,8
JNE TMRINT1
SUB AH,AH

INC BX
MOV CH,[BX]
CMP BX,FILELEN
JNZ TMRINT1
INC BP

TMRINT1:
MOV AL,20H
OUT 20H,AL
IRET

TIMERINT ENDP

;-------------------------------------------

PARM DB 128 DUP (0)

SPECERRMSG DB 'File specification'
DB ' error',0DH,0AH,24H

;it is assumed that DS and ES both point
; to the PSP.

PARSESGL PROC

CLD
MOV DI,80H
MOV CL,[DI]
SUB CH,CH
INC DI

CMP CX,1
JBE PARSS4

;find first non-blank character

MOV AL,20H
REPE SCASB
JNE PARSS2
PARSS4: PUSH CS
POP DS
MOV DX,OFFSET SPECERRMSG
MOV AH,9
INT 21H
MOV AX,4C01H
INT 21H

;find next blank character or end

PARSS2:
DEC DI
INC CX
MOV BX,DI
REPNE SCASB

;save parameter

JCXZ PARSS3
DEC DI
PARSS3: PUSH CX
PUSH DI
PUSH ES
PUSH CS
POP ES
MOV CX,DI
SUB CX,BX
MOV SI,BX
MOV DI,OFFSET PARM
REP MOVSB
POP ES
POP DI
POP CX

RET

PARSESGL ENDP

;-------------------------------------------

CODE ENDS

;-------------------------------------------

HIMEM SEGMENT PARA
HIMEM ENDS

END START