3D allocation efficient for 1D and 2D models

fdelmodc3D/alloc3D.c

+#include <stdlib.h>
+#include"fdelmodc3D.h"
+
+/* Copyright (c) Colorado School of Mines, 2011.*/
+/* All rights reserved.                       */
+
+/* allocate a 3-d array of floats */
+float ***alloc3float(modPar mod)
+{
+    size_t i3,i2,n1,n2,n3,size;
+    float ***p;
+
+	n1 = mod.naz;
+	n2 = mod.nax;
+	n3 = mod.nay;
+	size = sizeof(float);
+
+/* allocate pointer arrays of n3 and n2 */
+    if ((p=(float***)malloc(n3*sizeof(float**)))==NULL)
+        return NULL;
+    if ((p[0]=(float**)malloc(n3*n2*sizeof(float*)))==NULL) {
+        free(p);
+        return NULL;
+    }
+
+/* allocate data size and assign pointers to n1, n2 and n3 */
+	if (mod.nfx==1 && mod.nfy==1 ) { // 1D model 
+		fprintf(stderr,"Allocating 1D model \n");
+        if ((p[0][0]=(float*)malloc(n1*size))==NULL) {
+            free(p);
+            return NULL;
+        }
+        for (i3=0; i3<n3; i3++) {
+            p[i3] = p[0];
+            for (i2=0; i2<n2; i2++)
+                p[i3][i2] = (float*)p[0][0];
+        }
+	}
+	else if (mod.nfy==1) { // 2D model
+		fprintf(stderr,"Allocating 2D model \n");
+        if ((p[0][0]=(float*)malloc(n2*n1*size))==NULL) {
+            free(p);
+            return NULL;
+        }
+        for (i3=0; i3<n3; i3++) {
+            p[i3] = p[0];
+            for (i2=0; i2<n2; i2++)
+                p[i3][i2] = (float*)p[0]+n1*i2;
+        }
+	}
+	else { // 3D model 
+		fprintf(stderr,"Allocating 3D model \n");
+        if ((p[0][0]=(float*)malloc(n3*n2*n1*size))==NULL) {
+            free(p[0]);
+            free(p);
+            return NULL;
+        }
+        for (i3=0; i3<n3; i3++) {
+            p[i3] = p[0]+n2*i3;
+            for (i2=0; i2<n2; i2++)
+                p[i3][i2] = (float*)p[0][0]+n1*(i2+n2*i3);
+        }
+	}
+    return p;
+}
+
+void free3float(float ***p)
+{
+    free(p[0][0]);
+    free(p[0]);
+    free(p);
+}
+