1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
|
/* Memorybuffer2Texture.c -- Minimal example of how to
* pass a pointer to a memory buffer to Psychtoolbox,
* so that one can create a texture out of its content.
*
* This simple example creates a 640 x 480 pixels color
* image in a memory buffer and returns a pointer to it
* to Matlab, encoded as a double value: The way we encode
* the pointer as double may look clumsy, but it guarantees
* that it works even on 64-Bit systems.
*
* Compile with: mex Memorybuffer2Texture.c
* Then run Memorybuffer2TextureDemo.m
*
* Written by Mario Kleiner.
*/
#include "mex.h"
/* Byte array with 640 x 480 RGB pixels */
unsigned char rawimage[640 * 480 * 3];
/* Definition of a 64-bit number: Operating system dependend: */
#ifndef __WIN32__
/* Unix style: */
typedef unsigned long long psych_uint64;
#else
/* Microsoft Windows style: */
typedef LONG psych_uint64;
#endif
/* Convert a memory address pointer into a double value: */
double PtrToDouble(void* ptr)
{
volatile psych_uint64 ival = (psych_uint64) ptr;
volatile double* dptr = (double*) &ival;
volatile double outval = *dptr;
return(outval);
}
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray*prhs[])
{
int x,y, pos;
double dblimgptr;
static int counter = 0;
/* Fill our rawimage image array with content: */
pos = 0;
for(y=0; y<480; y++)
for (x=0; x<640; x++) {
/* Red channel: */
rawimage[pos++] = (unsigned char) x;
/* Green channel: */
rawimage[pos++] = (unsigned char) y;
/* Blue channel: */
rawimage[pos++] = (unsigned char) 0;
}
/* Convert our memory pointer to something Psychtoolbox
understands, i.e., convert it into a double value:
*/
dblimgptr = PtrToDouble((void*) &rawimage);
/* Return double-encoded pointer to Matlab: */
plhs[0]=mxCreateDoubleMatrix(1, 1, mxREAL);
*mxGetPr(plhs[0]) = dblimgptr;
/* Little extra test: Return an incrementing counter value */
/* to caller, but in input argument 1, to check if this trick works. */
if (nrhs > 0) {
*mxGetPr(prhs[0]) = (double) counter++;
}
}
|
