hgt: runtime optimization

src/Lib/HGT/hgt.cxx

@@ -58,16 +58,12 @@ TGHgt::TGHgt( int _res )
     hgt_resolution = _res;
 
     data = new short int[MAX_HGT_SIZE][MAX_HGT_SIZE];
-    output_data = new short int[MAX_HGT_SIZE][MAX_HGT_SIZE];
+    read_buffer = new short int[MAX_HGT_SIZE];
 }
 
 
-TGHgt::TGHgt( int _res, const SGPath &file )
+TGHgt::TGHgt( int _res, const SGPath &file ) : TGHgt( _res )
 {
-    hgt_resolution = _res;
-    data = new short int[MAX_HGT_SIZE][MAX_HGT_SIZE];
-    output_data = new short int[MAX_HGT_SIZE][MAX_HGT_SIZE];
-
     TGHgt::open( file );
 }
 
@@ -164,16 +160,21 @@ TGHgt::load( ) {
         return false;
     }
 
-    short int *var;
+    
     for ( int row = size - 1; row >= 0; --row ) {
-        for ( int col = 0; col < size; ++col ) {
+        if ( gzfread( (voidp)read_buffer, 2, size, fd ) != (unsigned)size ) {
-            var = &data[col][row];
+            return false;
-            if ( gzread ( fd, var, sizeof(short) ) != sizeof(short) ) {
+        }
-                return false;
+
-            }
+        // convert to column-major
-            if ( sgIsLittleEndian() ) {
+        for ( int col = 0; col < size; ++col )
-                sgEndianSwap( (unsigned short int*)var);
+            data[col][row] = *(read_buffer + col);
-            }
+    }
+
+    if (sgIsLittleEndian()) {
+        auto pData = (unsigned short *)data;
+        for (int i = 0; i < rows * cols; ++i) {
+            sgEndianSwap(pData++);
         }
     }
 
@@ -181,9 +182,8 @@ TGHgt::load( ) {
 }
 
 
-
 TGHgt::~TGHgt() {
     // printf("class TGSrtmBase DEstructor called.\n");
     delete [] data;
-    delete [] output_data;
+    delete [] read_buffer;
 }

src/Lib/HGT/hgt.hxx

@@ -53,7 +53,7 @@ private:
     
     // pointers to the actual grid data allocated here
     short int (*data)[MAX_HGT_SIZE];
-    short int (*output_data)[MAX_HGT_SIZE];
+    short int *read_buffer;
 
 public: