oop oops

[flipflop]

Hi i'm new to the forum and im struggling to find a solution to a problem im having

i have been trying to create structs and call them correctly however i dont seem to be able to get it to compile
i could do with a few links to tutorials that cover this or an example that i can follow to see where im going wrong

i need a struct that is recursive eg

Code Select Expand


mystruct STRUCT DWORD
next mystruct ?
value DWORD ?
mystruct ENDS


have i made any mystakes here?
i also would like an example of the code that can set both values correctly and pass these values correctly to other procs

please help i haven't done any coding in assembler for years and its all changed.

p.s. know any good profilers debuggers that display your own source as they step through the programs?

cheers flipflop

[qWord]

you can not use a structure inside it's definition:

Code Select Expand

mystruct STRUCT DWORD
next PVOID ?
value DWORD ?
mystruct ENDS

[flipflop]

if that is the case how would i go about creating a dynamic tree or list

[qWord]

if that is the case how would i go about creating a dynamic tree or list

as shown: use pointers

Code Select Expand

mystruct STRUCT DWORD
next PVOID ?  ; pointer to next node/element. PVOID == DWORD == 32Bit
value DWORD ?
mystruct ENDS

[flipflop]

cheers

ill give that a try

[flipflop]

ok so i have my struct

Code Select Expand


mystruct STRUCT DWORD
next PVOID ?
value DWORD ?
mystruct ENDS

and im setting the value using

Code Select Expand



initmystruct proc mystruct:PVOID
    mov eax,mystruct
    mov (mystruct PTR [eax]).value,0
    mov (mystruct PTR [eax]).next,0
    ret
initmystruct endp


this compiles but crashes
ive read some where that the angle brackets make no difference :red

[qWord]

The code is OK - propably you are passing an invalid pointer to the function.
You may show us your full code.

[bomz]

.386

.model flat, stdcall
option casemap :none

include \MASM32\INCLUDE\windows.inc
include \MASM32\INCLUDE\user32.inc
include \MASM32\INCLUDE\kernel32.inc
includelib \MASM32\LIB\user32.lib
includelib \MASM32\LIB\kernel32.lib

initmystruct proto :DWORD

mystruct STRUCT
next PVOID ?
value DWORD ?
mystruct ENDS

.data

.data?

.code
start:

invoke ExitProcess,0

initmystruct proc mystruct1:PVOID
    assume eax:ptr mystruct
   mov eax, mystruct1
    mov [eax].value,0
    mov [eax].next,0
   assume eax:nothing
    ret
initmystruct endp

end start

[flipflop]

thankyou bomz
much better than what i had wrote. very helpful

Code Select Expand

scanner proc bufferptr:DWORD,buffersize:DWORD
    LOCAL mystruct :PVOID
    invoke initmystruct,mystruct
    .....more code that does not get executed.......
    ret
scanner endp


this is the code fragment that causes the crash (i put print statements all through my code to find this)

[clive]

this is the code fragment that causes the crash (i put print statements all through my code to find this)

Presumably because you need to be passing the address of an actual structure to fill, not a pointer to a pointer, or an empty pointer.

[bomz]

This in form which make code much READABLE, but mean this:

initmystruct proc mystruct1:PVOID
   mov dword ptr[mystruct1],0
   mov dword ptr[mystruct1+4],0
   ret
initmystruct endp

[qWord]

Your variable mystruct (which has the same name as the structure?), is not initialized.

Code Select Expand

...
LOCAL pMystruct:PVOID
mov pMyStruct,alloc(SIZEOF MYSTRUCT) ; allocate new structure
invoke initmystruct,pMyStruct
...
or

Code Select Expand

...
LOCAL Mystruct:MYSTRUCT
invoke initmystruct,ADDR Mystruct  ; pass pointer to structure
...

MASM has several syntax variantion for accessing structure members through pointers. A common way is: [register].STRUCTURENAME.member

[flipflop]

cheers brilliant just what i was looking for very helpful indeed thankyou everyone for replies  :U