why doesn't this work, I'm missing somthing
; Playing with array's
; Creates a 4x2 matrix of ints
; array of pointer to array's
; example 4x2 matrix
;
- ->[1][2]
; [1]->[3][4]
; [2]->[5][6]
; [3]->[7][8]
.586
.model flat, C
option casemap :none
.data
.code
;-------------------------------------------------------------------
; void matrx_ptrs(int **intmat,int rows, int cols); cpp calling function
;-------------------------------------------------------------------
matrx_ptrs proc public intmat:PTR DWORD, rows:DWORD, cols:DWORD
push eax
push ebx
push ecx
push edx
;--------------- calc size ---------------------
mov ebx, rows
imul ebx,cols
add ebx, rows
;------------------------------------------------------
mov edx, intmat ; matrix [rows][cols]
mov ecx,rows ; row counter start at end of rows
mov eax,1 ; integer value starting at one to add to matrix
.while(ecx < ebx) ; should be 4-12
mov [edx+ecx*4],eax
add eax,1
add ecx,1
.endw
pop edx
pop ecx
pop ebx
pop eax
ret
matrx_ptrs endp
end
Quote from: nibbleNbits on December 11, 2011, 12:31:50 PM;-------------------------------------------------------------------
; void matrx_ptrs(int **intmat,int rows, int cols); cpp calling function
;-------------------------------------------------------------------
matrx_ptrs proc public intmat:PTR DWORD, rows:DWORD, cols:DWORD
...
mov edx, intmat ; matrix [rows][cols]
You must dereference the pointer a second time by:
mov edx,[edx]Alternatively you can change the Cpp function:
Quote; void matrx_ptrs(int *intmat,int rows, int cols); cpp calling function
Quote from: nibbleNbits on December 11, 2011, 12:31:50 PM
;--------------- calc size ---------------------
mov ebx, rows
imul ebx,cols
add ebx, rows ; <- ???
You are calculating the number of cells and not the size.
c/cpp requires the ** notation. it works fine in c++
int val = 0;
for(int i = 0;i < rows; i++)
for(int j = 0; j < cols; j++)
{
intmat[j] = val;
val++;
}
I added mov edx, [edx] but that didn't help
mov edx, [intmat]
mov edx, [edx]
I realized that about calculating rows and not the size, poor choice of words :red
still does't work
Quote from: nibbleNbits on December 11, 2011, 01:41:51 PM
c/cpp requires the ** notation.
surely not: you can simply use an two dimensional integer array.
The following code is speculative, because I don't know the data type of
intmat:
mov edi,intmat ; -> push/pop edi
; edi = pointer to array of 'row'-pointers
xor eax,eax
mov edx,1 ; skip first row
.while edx < rows
mov esi,PDWORD ptr [edi+edx*4] ; -> push/pop esi
; esi = pointer to row[edx]
xor ecx,ecx
.while ecx < cols
; loop through all elements in row
mov SDWORD ptr [esi+ecx*4],eax
lea eax,[eax+1]
lea ecx,[ecx+1]
.endw
lea edx,[edx+1]
.endw
qWord thanks for you input and help. If I use a int[4][2] and a slightly different masm algo I can make it work just fine, however I don't alway know the size. Hence the reason for dynamic allocation using pointers, in this case pointer to pointers,
int **intmat;
intmat = new int*[rows];
for(int i= 0; i < rows; i++)
intmat = new int[cols];
anyway you algo works fine except the first row? not sure I have figured out just yet why you skipped row 1? the last (3) rows come out correct.
again thanks so much for you input
I changed mov edx,1 ; skip first row to mov edx,0 ; skip first row and all is well, almost orgasm time.
thanks again
Quote from: nibbleNbits on December 11, 2011, 03:01:37 PManyway you algo works fine except the first row? not sure I have figured out just yet why you skipped row 1? the last (3) rows come out correct.
Reading your first post, I thought that you want to skip the first row.
qWord