Reading a BYTE array into a DWORD array with a loop

Question

This is a question identical to previous post. The objective is to take a BYTE array of 2, 4, 6, 8 ,10 and insert them into a DWORD array via a LOOP to display them. This is my latest attempt.

INCLUDE Irvine32.inc

.data

Array1 BYTE 2,4,6,8,10
Array2 DWORD 5 dup(0)

.code
main PROC


 mov esi, OFFSET Array1  ;esi = byteArray
 mov edi, OFFSET Array2  ;edi = dwordArray
 mov ecx, 5              ;counter of loop


 DAWG:
     mov eax, [esi]   ;attempting to use movzx causes errors
     mov [edi], eax
     inc esi
     add edi, 4
     loop DAWG

Any suggestions? Trying to figure it out with my bit (pun intended) of assembly knowledge. Thanks for reading.

It indeed does. Thanks! For my knowledge, why does byte ptr make the statement work? — caboose103
– caboose103, Commented Sep 26, 2015 at 18:57
The assembler has to know, how much of [esi] is to be loaded into EAX, since there are different machine instructions for that purpose. byte ptr means: take one byte. — rkhb
– rkhb, Commented Sep 26, 2015 at 19:02

Sep Roland · Accepted Answer · 2015-09-27 19:13:28Z

3

1st solution as suggested by @rkhb is

DAWG:
 movzx eax, byte ptr [esi]
 mov   [edi], eax
 inc   esi
 add   edi, 4
 loop  DAWG

I would like to add this slightly more elegant solution:

 cld
 xor   eax, eax
DAWG:
 lodsb
 stosd
 loop  DAWG

answered Sep 27, 2015 at 19:13

Sep Roland

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