diff Problems/private/im2colstep.c @ 15:51b76c31c93d

(none)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Problems/private/im2colstep.c	Thu Mar 25 14:05:27 2010 +0000
@@ -0,0 +1,131 @@
+/**************************************************************************
+ *
+ * File name: im2colstep.c
+ *
+ * Ron Rubinstein
+ * Computer Science Department
+ * Technion, Haifa 32000 Israel
+ * ronrubin@cs
+ *
+ * Last Updated: 31.8.2009
+ *
+ *************************************************************************/
+
+
+#include "mex.h"
+#include <string.h>
+
+
+/* Input Arguments */
+
+#define	X_IN	 prhs[0]
+#define SZ_IN  prhs[1]
+#define S_IN   prhs[2]
+
+
+/* Output Arguments */
+
+#define	B_OUT	plhs[0]
+
+
+void mexFunction(int nlhs, mxArray *plhs[], 
+		             int nrhs, const mxArray*prhs[])
+     
+{ 
+    double *x, *b, *s;
+    mwSize sz[3], stepsize[3], n[3], ndims;
+    mwIndex i, j, k, l, m, blocknum;
+    
+    
+    /* Check for proper number of arguments */
+    
+    if (nrhs < 2 || nrhs > 3) {
+      mexErrMsgTxt("Invalid number of input arguments."); 
+    } else if (nlhs > 1) {
+      mexErrMsgTxt("Too many output arguments."); 
+    } 
+    
+    
+    /* Check the the input dimensions */ 
+    
+    ndims = mxGetNumberOfDimensions(X_IN);
+    
+    if (!mxIsDouble(X_IN) || mxIsComplex(X_IN) || ndims>3) {
+      mexErrMsgTxt("X should be a 2-D or 3-D double matrix.");
+    }
+    if (!mxIsDouble(SZ_IN) || mxIsComplex(SZ_IN) || mxGetNumberOfDimensions(SZ_IN)>2 || mxGetM(SZ_IN)*mxGetN(SZ_IN)!=ndims) {
+      mexErrMsgTxt("Invalid block size.");
+    }
+    if (nrhs == 3) {
+      if (!mxIsDouble(S_IN) || mxIsComplex(S_IN) || mxGetNumberOfDimensions(S_IN)>2 || mxGetM(S_IN)*mxGetN(S_IN)!=ndims) {
+        mexErrMsgTxt("Invalid step size.");
+      }
+    }
+    
+    
+    /* Get parameters */
+    
+    s = mxGetPr(SZ_IN);
+    if (s[0]<1 || s[1]<1 || (ndims==3 && s[2]<1)) {
+      mexErrMsgTxt("Invalid block size.");
+    }
+    sz[0] = (mwSize)(s[0] + 0.01);
+    sz[1] = (mwSize)(s[1] + 0.01);
+    sz[2] = ndims==3 ? (mwSize)(s[2] + 0.01) : 1;
+    
+    if (nrhs == 3) {
+      s = mxGetPr(S_IN);
+      if (s[0]<1 || s[1]<1 || (ndims==3 && s[2]<1)) {
+        mexErrMsgTxt("Invalid step size.");
+      }
+      stepsize[0] = (mwSize)(s[0] + 0.01);
+      stepsize[1] = (mwSize)(s[1] + 0.01);
+      stepsize[2] = ndims==3 ? (mwSize)(s[2] + 0.01) : 1;
+    }
+    else {
+      stepsize[0] = stepsize[1] = stepsize[2] = 1;
+    }
+    
+    n[0] = (mxGetDimensions(X_IN))[0];
+    n[1] = (mxGetDimensions(X_IN))[1];
+    n[2] = ndims==3 ? (mxGetDimensions(X_IN))[2] : 1;
+    
+    if (n[0]<sz[0] || n[1]<sz[1] || (ndims==3 && n[2]<sz[2])) {
+      mexErrMsgTxt("Block size too large.");
+    }
+    
+    
+    /* Create a matrix for the return argument */
+    
+    B_OUT = mxCreateDoubleMatrix(sz[0]*sz[1]*sz[2], ((n[0]-sz[0])/stepsize[0]+1)*((n[1]-sz[1])/stepsize[1]+1)*((n[2]-sz[2])/stepsize[2]+1), mxREAL);
+    
+    
+    /* Assign pointers */
+    
+    x = mxGetPr(X_IN);
+    b = mxGetPr(B_OUT);
+            
+    
+    /* Do the actual computation */
+    
+    blocknum = 0;
+    
+    /* iterate over all blocks */
+    for (k=0; k<=n[2]-sz[2]; k+=stepsize[2]) {
+      for (j=0; j<=n[1]-sz[1]; j+=stepsize[1]) {
+        for (i=0; i<=n[0]-sz[0]; i+=stepsize[0]) {
+          
+          /* copy single block */
+          for (m=0; m<sz[2]; m++) {
+            for (l=0; l<sz[1]; l++) {
+              memcpy(b + blocknum*sz[0]*sz[1]*sz[2] + m*sz[0]*sz[1] + l*sz[0], x+(k+m)*n[0]*n[1]+(j+l)*n[0]+i, sz[0]*sizeof(double));
+            }
+          }
+          blocknum++;
+          
+        }
+      }
+    }
+    
+    return;
+}