I am trying to run this code written by my professor. Unfortunately, when I compile and run the code, the results:
INCLUDE Irvine32.inc
.data
ARRAY_SIZE = 1000
FILL_VAL EQU 0FFh
hHeap HANDLE ? ;Handle to the process heap
pArray DWORD ? ;pointer to block of memory
newHeap DWORD ? ;handle to new heap
str1 BYTE "Heap size is: ",0
GetProcessHeap PROTO
.code
main PROC
INVOKE GetProcessHeap ;get handle prog's heap
.IF eax = NULL ;If failed, display message
call WriteWindowsMsg
jmp quit
.ELSE
mov hHeap, eax ;success
.ENDIF
call allocate_array
jnc arrayOk ;failed (CF = 1)?
call WriteWindowsMsg
call Crlf
jmp quit
arrayOk:
call fill_array
call display_array
call Crlf
;free the array
INVOKE HeapFree, hHeap, 0, pArray
quit:
exit
main ENDP
;-------------------------------------------------------
allocate_array PROC USES eax
;
;Dynamically allocates space for the array
;Receives: EAX = handle to the program heap
;Returns: CF = 0 if the memory allocation succeeds
;-------------------------------------------------------
INVOKE HeapAlloc, hHeap, HEAP_ZERO_MEMORY, ARRAY_SIZE
.IF eax == NULL
stc ;return with CF = 1
.ELSE
mov pArray, eax ;save the pointer
clc ;return with CF = 0
.ENDIF
ret
allocate_array ENDP
;--------------------------------------------------------
fill_array PROC USES ecx edx esi
;
;Fills all array positions with a single character
;Receives: nothing
;Returns: nothing
;---------------------------------------------------------
mov ecx, ARRAY_SIZE ;loop counter
mov esi, pArray ;point to the array
L1: mov BYTE PTR [esi], FILL_VAL ;fill each byte
inc esi ;next location
loop L1
ret
fill_array ENDP
;---------------------------------------------------------
display_array PROC USES eax ebx ecx esi
; Displays the array
; Receives: nothing
; Returns: nothing
mov ecx, ARRAY_SIZE ;loop counter
mov esi, pArray ;point to the array
L1: mov al, [esi] ;get a byte
mov ebx, TYPE BYTE
call WriteHexB ;display it
inc esi ;next location
loop L1
ret
display_array ENDP
END main
The following results:
bobnew.asm(41) : error A2006: undefined symbol : HeapFree
bobnew.asm(56) : error A2006: undefined symbol : HeapAlloc
bobnew.asm(22) : error A2006: undefined symbol : WriteWindowsMsg
bobnew.asm(30) : error A2006: undefined symbol : WriteWindowsMsg
bobnew.asm(97) : error A2006: undefined symbol : WriteHexB
Can someone explain why. Thanks. I am also curious to how Heap memory Allocation and how Invoke and Handlers and Proto works together. I understand that heap is memory set aside for dynamic memory allocation and unlike stack, there's no set pattern to how memory is allocated or deallocated. You can allocate and deallocate at any time randomly and free those allocated memory any time. Also, unlike stack, heap memory must be manually destroyed to prevent memory.
How are you building the executable?
In order to use functions like HeapFree, you need to link with kernel32. How to do this can vary by which linker you're using. In MASM this may mean writing
include \masm32\include\kernel32.inc
includelib \masm32\lib\kernel32.lib