Hello,
I'm newbie in asm. I'm try to learn from the tutorial folder from masm32 SDK, and in tutorial/console/demo6/address.asm have this lines:
LOCAL cnt :DWORD ; allocate a loop counter
push esi
push edi
mov cnt, 10 ; set the number of loop iterations
mov esi, array ; put array address into ESI
When I'm trying to comment the push statements the program run perfectly without them, so why we need to write it?
Thanks,
Michael
Hi Michael,
First of all, welcome to the forum :icon14:
Pushing esi and edi on the stack keeps their values for other procedures, including those of Windows itself. More here (http://www.webalice.it/jj2006/Masm32_Tips_Tricks_and_Traps.htm) in the section The "register gets trashed" trap
Sometimes the program works without push esi + pop esi, but it just means you were lucky - you cannot rely on this behaviour. The rules are clear...
Thanks!
P.s: why I', always should answer those questions? Type the letters shown in the picture:, Was Musolini German, Italian, Russian or Chinese ?:, If English is one of the 2 main languages in Canada, what is the other ?: etc.. LOL
Hi
The other way is but, same effect
main proc uses esi edi
After compile it have you again
push esi
push edi
0040100C /$ 55 PUSH EBP
0040100D |. 8BEC MOV EBP,ESP
0040100F |. 83C4 FC ADD ESP,-4
00401012 |. 56 PUSH ESI <<<<<<<<<<
00401013 |. 57 PUSH EDI <<<<<<<<<<
00401014 |. C745 FC 0A000>MOV [LOCAL.1],0A
Quote from: mikichi on January 03, 2017, 08:47:10 AMWas Musolini German, Italian, Russian or Chinese ?:, If English is one of the 2 main languages in Canada, what is the other ?: etc.. LOL
That will stop after a few posts, don't worry :biggrin:
main proc uses esi ediWhat ragdog means is: With this shorter notation, Masm will insert the push/pop to preserve the registers. Easy and convenient. You will often see sometest proc
uses esi edi ebx arg1, arg2
Very informative! thank you again guys!