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

;-------------------------tdecshow routine begins--------------------------+
; from BLUEBOOK OF ASSEMBLY ROUTINES FOR IBM PC & XT.
; page : 95
;
; NAME TDECSHOW
;
; ROUTINE FOR DISPLAY OF FLOATING POINT
;
; FUNCTION: This routine displays a floating point number on the std
; output device.
;
; INPUT: Upon input a number is stored in temporary decimal floating point
; form. The temporary format has a string of 25 decimal digits, a sign
; byte, and a base ten exponent which is stored in two's complement 16-bit
; binary format (Fig 5-5).
;
; OUTPUT: The individual characters of a floating point number are sent
; out the standard output device. The form of the output is: a sign char-
; acter which is blank or minus, followed by decimal digits of the mantissa
; with one imbedded decimal point to the right of the first significant
; digit. Following the mantissa is an exponent which starts with the letter
; 'E', then a sign, then a d8cimal number (Fig 5-4).
;
; REGISTERS USED: AL, CX, DX and SI are modified.
;
; SEGMENTS REFERENCED: The data segment contains the variables DECBUFF
; (25 BYTES), DECSIGN (1 byte), and DECEXP (2 bytes).
;
; ROUTINES CALLED: STDOUT, DEC16OUT
;
; SPECIAL NOTES: This is a near procedure needed by FPOUT.
;
; ROUTINE TO DISPLAY TEMPORARY DECIMAL FLOATING POINT NUMBERS
;
tdecshow proc near
;
; output the sign
cmp decsign,0 ; is the sign there ?
mov al,' ' ; space if not
je decshow1
;
; output a minus sign
mov al,'-' ; minus sign
;
tdecshow1:
call stdout ; send it out
;
tdecshow2:
; output the first digit and a decimal point
lea si,decbuff+21 ; point to the first digit
mov al,[si] ; get it
dec si ; point to next digit
add al,30h ; convert to ASCII
call stdout ; send it out
;
mov al,'.' ; ASCII decimal point
call stdout ; send it out
;
; output the rest of the decimal string
mov cx,7 ; only seven more digits
;
tdecshow3:
mov al,[si] ; get digit
dec si ; point to next digit
add al,30h ; convert to ASCII
call stdout ; send it out
loop tdecshow3 ; until all digits sent
;
mov al,'E' ; E for (E)xponent
call stdout ; send it out
;
; now the exponent
mov dx,decexp ; grab the exponent
cmp dx,0 ; check sign
mov al,'+' ; plus sign
jge tdecshow4 ; if non-negative
;
; if negative exponent
neg dx ; absolute value of exponent
mov al,'-' ; minus sign
;
tdecshow4:
call stdout ; output sign of exponent
call dec16out ; output exponent
;
ret ; return
;
tdecshow endp
;-------------------------tdecshow routine ends---------------------------+