How to copy one string to another? 2

[zorica]

I need some help with string coping. How to write 32 bit code and copy string1 (e.g. "I am a student&quotto an empty string2.

 

[datac5155]

If you know the length of the string to copy all you need to do is use movsb.

cld
ESI = place to copy to
DS:SI = place copying from
CX = # of characters to copy
REP movsb = Repeat mov until CX = 0

Hope this helps you.

"It is the struggle itself that is most important. It does not matter that we will never reach our ultimate goal." DataC5155

"...NO FATE..."

 

[AmkG]

For 32-bit code, assuming flat model, the above are:

edi = place to copy to
esi = place to copy from
ecx = length of string (in bytes)
REP MOVSB ;REPeat: MOVe a String by Bytes

or better yet:
edi = place to copy to
esi = place to copy from
ecx = length of string (in bytes)
;we'll be needing it later on
push ecx
;we will move the string by DWORDS so divide length
;(in bytes) by 4 to get length in DWORDS
shr ecx,2
rep movsd ; REPeat: MOVe a String by Dwords
;however any extra bytes that don't fit into a DWORD will
;not get copied yet, so copy them too...
pop ecx
and ecx,03h
;if there are no extra bytes to copy, leave.
cmp ecx,0
je exit
rep movsb ;copy extra bytes that don't fit into a dword

"Information has a tendency to be free. Which means someone will always tell you something you don't want to know."

 

[datac5155]

Show Off
You have to leave SOME of the work up to them.
But you got me on the E's. I missed the 32-Bit Part the first time I read the question. DataC5155

"...NO FATE..."

 

[AmkG]

That's what I like about this forum... I can always show off to n00bs!!!

"Information has a tendency to be free. Which means someone will always tell you something you don't want to know."