Notes

.model small

initds macro mov ax,@data ; Initializing the Data Segment mov ds,ax ; it is ds, not dx endm

printf macro msg lea dx,msg ; Load the Effective Address to DX mov ah,9 ; Function Number is 9 int 21h ; Using DOS interrupt 21h endm

putchar macro char mov dl,char ; load the printable character's HEX value in DL mov ah,2 ; Function Number is 9 int 21h ; Using DOS interrupt 21h endm

exit macro mov ah,4ch ; to terminate int 21h endm

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; .data array dw 1122h,2345h,3333h,4455h,6666h ; 16 bit array len dw ($-array)/2 ; len = (last_index - first_index)/2 search equ 2345h ; key to Search foundmsg db 'Element found at position : $' position db 0 ; now it’s 0, later we shall put notfoundmsg db 'Element not found $' .code initds ; Initializing Data Segment (call that macro) mov bx,1 ; low mov dx,len ; high mov cx,search ; key again: cmp bx,dx ; while(low<high) ja failure ; if (low>high) then its not found case. mov ax,bx add ax,dx ; low+high shr ax,1 ; (low+high) /2 mov si,ax ; have an index


dec si ; adjust the index (pointing to the mid) add si,si ; for 16 bit data cmp cx,array[si] ; if(key==array[mid]) jae bigger ; search in the RIGHT part of the array dec ax ; dec high (search in the LEFT part of the array) mov dx,ax ; make this as new high jmp again ; continue searching bigger: je success ; found case inc ax ; inc low mov bx,ax ; make this as new low jmp again ; continue searching success: add al,30h ; add 30h (or '0') to the position(AL) ; (just to convert to ascii) mov position,al ; move the position to our variable printf foundmsg ; printing found message putchar position ; printing found position exit ; you are done, so bye bye! failure: printf notfoundmsg ; printing not found message exit ; bye! end