Category : Assembly Language Source Code
Archive   : ASM-SUBR.ZIP
Filename : OCT16IN

;-------------------------oct16in routine begins--------------------------+
; from BLUEBOOK OF ASSEMBLY ROUTINES FOR IBM PC & XT.
; page : 45
;
; NAME OCT16IN
; ROUTINE FOR conversion from ASCII octal to 16-bit Binary
;
; FUNCTION: This routine accepts an octal number from the standard input
; device and converts it to internal 16-bit binary form.
; INPUT: The individual digits of the octal number are received in ASCII
; through a call to a standard I/O routine. The valid digits are 0 - 7.
; An ASCII code other than for a valid digit will terminate the routine.
;
; OUTPUT: A 16-bit binary number is returned in the DX register.
; REGISTERS USED: Only DX is modified. It returns the result.
; SEGMENTS REFERENCED: None
; ROUTINES CALLED: STDIN
; SPECIAL NOTES: None
;
; ROUTINE TO CONVERT FROM ASCII OCTAL TO INTERNAL 16-BIT BINARY
;
oct16in proc far
;
push cx ; save registers
push ax
;
mov dx,0 ; initialize DX
;
oct16in1:
call stdin ; a digit comes in in AL
sub al,30h ; reduce from ASCII
jl oct16in2 ; check if too low
cmp al,7
jg oct16in2 ; check if too high
cbw ; convert to word
;
mov cl,3
sal dx,cl ; shift dx left once
add dx,ax ; add in digit
jmp oct16in1
;
oct16in2:
;
pop ax ; restore registers
pop cx
ret ; return
;
oct16in endp
;-------------------------oct16in routine ends---------------------------+