Loop over multiple arrays simultaneously: Difference between revisions

=={{header|8086 Assembly}}==

The 8086 processor has two index registers <code>si</code> and <code>di</code>,

and an address register <code>bx</code>. (There is also the base pointer <code>bp</code>,

which is used to point to the stack segment, and is not used here.)

When addressing memory, the 8086 can automatically add up: 1) one of <code>bx</code> or

<code>bp</code>, plus 2) one of <code>si</code> or <code>di</code>, plus 3)

a direct address.

This code uses <code>si</code> to keep track of the current index, and loads the

base addresses of the arrays into <code>bx</code> one by one.

<lang asm> cpu 8086

bits 16

org 100h

section .text

mov ah,2 ; Tell MS-DOS to print characters

xor si,si ; Clear first index register (holds _i_)

outer: mov di,As ; Put array-of-arrays in second index register

mov cx,Aslen ; Put length in counter register

inner: mov bx,[di] ; Load array pointer into BX (address) register

mov dl,[bx+si] ; Get SI'th element from array

int 21h ; Print character

inc di ; Go to next array (pointers are 2 bytes wide)

inc di

loop inner ; For each array

mov dl,13 ; Print newline

int 21h

mov dl,10

int 21h

inc si ; Increment index register

cmp si,Alen ; If it is still lower than the array length

jb outer ; Print the next items

ret

section .data

;;; Arrays

A1: db 'a','b','c'

A2: db 'A','B','C'

A3: db '1','2','3'

Alen: equ $-A3 ; Length of arrays (elements are bytes)

;;; Array of arrays

As: dw A1,A2,A3

Aslen: equ ($-As)/2 ; Length of array of arrays (in words)</lang>

{{out}}

<pre>aA1

bB2

cC3

</pre>