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

;-------------------------decdoubl routine begins--------------------------+
; from BLUEBOOK OF ASSEMBLY ROUTINES FOR IBM PC & XT.
; page : 103
;
; NAME DECDOUBL
;
; ROUTINE FOR Doubling A Temporary Decimal Floating Point Number
;
; FUNCTION: This routine multiplies a temporary decimal floating point
; number by two.
;
; INPUT: Upon ebtry DS:DI points to a temporary decimal floating point
; number.
;
; OUTPUT: Upon exit the number has been doubled.
;
; REGISTERS USED: AX, CX and DI are modified.
;
; SEGMENTS REFERENCED: The data segment contains storage for the temporary
; decimal floating poiint number.
;
; ROUTINES CALLED: None
;
; SPECIAL NOTES: This is a near procedure called by FPOUT
;
; ROUTINE TO MULTIPLY TEMPORARY DECIMAL FLOATING POINT NUMBER BY 2 - RESULT
; NOT NORMALIZED.
;
decdoubl proc near
;
mov cx,25 ; for a count of 25
mov ah,0 ; clear previous carry
;
decdoubl1:
mov al,[di] ; get digit
sal al,1 ; multip0ly by 2
and al,ah ; add the carry
aam ; adjust for decimal multiplication
mov [di],al ; put the byte back
inc di ; point to next byte
loop decdoubl1
;
ret ; return
;
decdoubl endp
;-------------------------decdoubl routine ends---------------------------+