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

;-------------------------bcdout routine begins--------------------------+
; from BLUEBOOK OF ASSEMBLY ROUTINES FOR IBM PC & XT.
; page : 66
;
; NAME BCDOUT
; ROUTINE FOR conversion from BCD to ASCII decimal
;
; FUNCTION: This routine converts a 36-digit number sstored in BCD form
; to ASCII decimal form which is sent to the std I/O device.
;
; INPUT: Upon entry a 36-digit number is stored in an 18-byte BCD buffer
; called BCDBUFF in the DATAS data segment.
;
; OUTPUT: A string of ASCII digits representing a decimal number is
; stored in a buffer called TBUFF and then sent out through a standard
; output device.
;
; REGISTERS USED: No registers are modified.
; SEGMENTS REFERENCED: DATAS is a data segment containing BCDBUFF
; and TBUFF.
;
; ROUTINES CALLED: STDOUT
; SPECIAL NOTES: None
;
; ROUTINE FOR CONVERSION FROM BCD TO ASCII DECIMAL
;
bcdout proc far
;
push ds ; save registers
push si
push dx
push cx
push ax
;
; set up a data segment
mov ax,datas ; point to data segment
mov ds,ax
;
mov cx,18 ; for a count of 18
lea si,bcdbuff ; point to bcd buffer
add si,17 ; point to end of bcd buffer
mov dh,0 ; clear flag for leading zeros
;
bdcout1:
push cx ; save count
mov al,[si] ; get BCD byte
dec si ; and point to next
mov dl,al ; save it
;
; upper digit
mov cl,4 ; for a count of four
rol al,cl ; rotate byte
and al,0Fh ; just the digit
or dh,al ; leading zeros?
jz bcdout2 ; if so skip digit
add al,30h ; make it ASCII
call stdout ; send it
;
bcdout2:
pop cx ; restore count
cmp cx,1 ; last digit ?
jnz bcdout3 ; skip if not
mov dh,0FFh ; set flag if so
;
bcdout3:
push cx ; save count
;
mov al,dl ; get byte back
;
; lower digit
and al,0Fh ; just the digit
or dh,al ; leading zeros?
jz bcdout4 ; if so skip digit
add al,30h ; make is ASCII
call stdout ; send it
;
bcdout4:
;
pop cx ; restore loop count
loop bcdout1
;
pop ax ; restore registers
pop cx
pop dx
pop si
pop ds
ret ; return
;
bcdout endp
;-------------------------bcdout routine ends---------------------------+