Added support for byte swapping based on endianess. Note the assumption is

that files are stored in little endian order so if reads or writes are done
from a big endian machine, the contents must be byte swapped.

simgear/io/lowlevel.cxx

@@ -33,193 +33,346 @@ void sgClearWriteError() { write_error = false; }
 int sgReadError() { return  read_error ; }
 int sgWriteError() { return write_error ; }
 
+static const int sgEndianTest = 1;
+#define sgIsLittleEndian (*((char *) &sgEndianTest ) != 0)
+#define sgIsBigEndian    (*((char *) &sgEndianTest ) == 0)
 
+static inline void sgEndianSwap(unsigned short *x) {
+    *x =
+        (( *x >>  8 ) & 0x00FF ) | 
+        (( *x <<  8 ) & 0xFF00 ) ;
+}
+  
+static inline void sgEndianSwap(unsigned int *x) {
+    *x =
+        (( *x >> 24 ) & 0x000000FF ) | 
+        (( *x >>  8 ) & 0x0000FF00 ) | 
+        (( *x <<  8 ) & 0x00FF0000 ) | 
+        (( *x << 24 ) & 0xFF000000 ) ;
+}
+  
+static inline void sgEndianSwap(unsigned long long *x) {
+    *x =
+        (( *x >> 56 ) & 0x00000000000000FFULL ) | 
+        (( *x >> 40 ) & 0x000000000000FF00ULL ) | 
+        (( *x >> 24 ) & 0x0000000000FF0000ULL ) | 
+        (( *x >>  8 ) & 0x00000000FF000000ULL ) | 
+        (( *x <<  8 ) & 0x000000FF00000000ULL ) | 
+        (( *x << 24 ) & 0x0000FF0000000000ULL ) |
+        (( *x << 40 ) & 0x00FF000000000000ULL ) |
+        (( *x << 56 ) & 0xFF00000000000000ULL ) ;
+}
+  
 void sgReadChar ( gzFile fd, char *var )
 {
-    if ( gzread ( fd, var, sizeof(char) ) == sizeof(char) ) return ;
+    if ( gzread ( fd, var, sizeof(char) ) != sizeof(char) ) {
-    read_error = true ;
+        read_error = true ;
+    }
 }
 
 
 void sgWriteChar ( gzFile fd, const char var )
 {
-    if ( gzwrite ( fd, (void *)(&var), sizeof(char) ) == sizeof(char) ) return ;
+    if ( gzwrite ( fd, (void *)(&var), sizeof(char) ) != sizeof(char) ) {
-    write_error = true ;
+        write_error = true ;
+    }
 }
 
 
 void sgReadFloat ( gzFile fd, float *var )
 {
-    if ( gzread ( fd, var, sizeof(float) ) == sizeof(float) ) return ;
+    if ( gzread ( fd, var, sizeof(float) ) != sizeof(float) ) {
-    read_error = true ;
+        read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        sgEndianSwap( (unsigned int*)var);
+    }
 }
 
 
 void sgWriteFloat ( gzFile fd, const float var )
 {
-    if ( gzwrite ( fd, (void *)(&var), sizeof(float) ) == sizeof(float) )
+    if ( sgIsBigEndian ) {
-	return ;
+        sgEndianSwap( (unsigned int*)&var);
-    write_error = true ;
+    }
+    if ( gzwrite ( fd, (void *)(&var), sizeof(float) ) != sizeof(float) ) {
+        write_error = true ;
+    }
 }
 
 
 void sgReadDouble ( gzFile fd, double *var )
 {
-    if ( gzread ( fd, var, sizeof(double) ) == sizeof(double) ) return ;
+    if ( gzread ( fd, var, sizeof(double) ) != sizeof(double) ) {
-    read_error = true ;
+        read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        sgEndianSwap( (unsigned long long*)var);
+    }
 }
 
 
 void sgWriteDouble ( gzFile fd, const double var )
 {
-    if ( gzwrite ( fd, (void *)(&var), sizeof(double) ) == sizeof(double) )
+    if ( sgIsBigEndian ) {
-	return ;
+        sgEndianSwap( (unsigned long long*)&var);
-    write_error = true ;
+    }
+    if ( gzwrite ( fd, (void *)(&var), sizeof(double) ) != sizeof(double) ) {
+        write_error = true ;
+    }
 }
 
 
 void sgReadUInt ( gzFile fd, unsigned int *var )
 {
-    if ( gzread ( fd, var, sizeof(unsigned int) ) == sizeof(unsigned int) )
+    if ( gzread ( fd, var, sizeof(unsigned int) ) != sizeof(unsigned int) ) {
-	return ;
+        read_error = true ;
-    read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        sgEndianSwap( (unsigned int*)var);
+    }
 }
 
 
 void sgWriteUInt ( gzFile fd, const unsigned int var )
 {
+    if ( sgIsBigEndian ) {
+        sgEndianSwap( (unsigned int*)&var);
+    }
     if ( gzwrite ( fd, (void *)(&var), sizeof(unsigned int) )
-	 == sizeof(unsigned int) )
+	 != sizeof(unsigned int) )
-	return ;
+    {
-    write_error = true ;
+        write_error = true ;
+    }
 }
 
 
 void sgReadInt ( gzFile fd, int *var )
 {
-    if ( gzread ( fd, var, sizeof(int) ) == sizeof(int) ) return ;
+    if ( gzread ( fd, var, sizeof(int) ) != sizeof(int) ) {
-    read_error = true ;
+        read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        sgEndianSwap( (unsigned int*)var);
+    }
 }
 
 
 void sgWriteInt ( gzFile fd, const int var )
 {
-    if ( gzwrite ( fd, (void *)(&var), sizeof(int) ) == sizeof(int) ) return ;
+    if ( sgIsBigEndian ) {
-    write_error = true ;
+        sgEndianSwap( (unsigned int*)&var);
+    }
+    if ( gzwrite ( fd, (void *)(&var), sizeof(int) ) != sizeof(int) ) {
+        write_error = true ;
+    }
 }
 
 
 void sgReadLong ( gzFile fd, long int *var )
 {
-    if ( gzread ( fd, var, sizeof(long int) ) == sizeof(long int) ) return ;
+    if ( gzread ( fd, var, sizeof(long int) ) != sizeof(long int) ) {
-    read_error = true ;
+        read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        sgEndianSwap( (unsigned int*)var);
+    }
 }
 
 
 void sgWriteLong ( gzFile fd, const long int var )
 {
-    if ( gzwrite ( fd, (void *)(&var), sizeof(long int) ) == sizeof(long int) )
+    if ( sgIsBigEndian ) {
-	return ;
+        sgEndianSwap( (unsigned int*)&var);
-    write_error = true ;
+    }
+    if ( gzwrite ( fd, (void *)(&var), sizeof(long int) )
+         != sizeof(long int) )
+    {
+        write_error = true ;
+    }
+}
+
+
+void sgReadLongLong ( gzFile fd, long long int *var )
+{
+    if ( gzread ( fd, var, sizeof(long long int) ) != sizeof(long long int) ) {
+        read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        sgEndianSwap( (unsigned long long int*)var);
+    }
+}
+
+
+void sgWriteLongLong ( gzFile fd, const long long int var )
+{
+    if ( sgIsBigEndian ) {
+        sgEndianSwap( (unsigned long long*)&var);
+    }
+    if ( gzwrite ( fd, (void *)(&var), sizeof(long long int) )
+         != sizeof(long long int) )
+    {
+        write_error = true ;
+    }
 }
 
 
 void sgReadUShort ( gzFile fd, unsigned short *var )
 {
-    if ( gzread ( fd, var, sizeof(unsigned short) ) == sizeof(unsigned short) )
+    if ( gzread ( fd, var, sizeof(unsigned short) ) != sizeof(unsigned short) ){
-	return ;
+        read_error = true ;
-    read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        sgEndianSwap( (unsigned short int*)var);
+    }
 }
 
 
 void sgWriteUShort ( gzFile fd, const unsigned short var )
 {
+    if ( sgIsBigEndian ) {
+        sgEndianSwap( (unsigned short*)&var);
+    }
     if ( gzwrite ( fd, (void *)(&var), sizeof(unsigned short) )
-	 == sizeof(unsigned short) )
+	 != sizeof(unsigned short) )
-	return ;
+    {
-    write_error = true ;
+        write_error = true ;
+    }
 }
 
 
 void sgReadShort ( gzFile fd, short *var )
 {
-    if ( gzread ( fd, var, sizeof(short) ) == sizeof(short) ) return ;
+    if ( gzread ( fd, var, sizeof(short) ) != sizeof(short) ) {
-    read_error = true ;
+        read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        sgEndianSwap( (unsigned short int*)var);
+    }
 }
 
 
 void sgWriteShort ( gzFile fd, const short var )
 {
-    if ( gzwrite ( fd, (void *)(&var), sizeof(short) ) == sizeof(short) ) return ;
+    if ( sgIsBigEndian ) {
-    write_error = true ;
+        sgEndianSwap( (unsigned short*)&var);
+    }
+    if ( gzwrite ( fd, (void *)(&var), sizeof(short) ) != sizeof(short) ) {
+        write_error = true ;
+    }
 }
 
 
 void sgReadFloat ( gzFile fd, const unsigned int n, float *var )
 {
-    if ( gzread ( fd, var, sizeof(float) * n ) == (int)(sizeof(float) * n) )
+    if ( gzread ( fd, var, sizeof(float) * n ) != (int)(sizeof(float) * n) ) {
-	return ;
+        read_error = true ;
-    read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned int*)var++);
+        }
+    }
 }
 
 
 void sgWriteFloat ( gzFile fd, const unsigned int n, const float *var )
 {
+    if ( sgIsBigEndian ) {
+        float *swab = new float[n];
+        float *ptr = swab;
+        memcpy( swab, var, sizeof(float) * n );
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned int*)ptr++);
+        }
+        var = swab;
+    }
     if ( gzwrite ( fd, (void *)var, sizeof(float) * n )
-	 == (int)(sizeof(float) * n) )
+	 != (int)(sizeof(float) * n) )
-	return ;
+    {
-    write_error = true ;
+        write_error = true ;
+    }
 }
 
 void sgReadDouble ( gzFile fd, const unsigned int n, double *var )
 {
-    if ( gzread ( fd, var, sizeof(double) * n ) == (int)(sizeof(double) * n) )
+    if ( gzread ( fd, var, sizeof(double) * n ) != (int)(sizeof(double) * n) ) {
-	return ;
+        read_error = true ;
-    read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned long long*)var++);
+        }
+    }
 }
 
 
 void sgWriteDouble ( gzFile fd, const unsigned int n, const double *var )
 {
+    if ( sgIsBigEndian ) {
+        double *swab = new double[n];
+        double *ptr = swab;
+        memcpy( swab, var, sizeof(double) * n );
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned long long*)ptr++);
+        }
+        var = swab;
+    }
     if ( gzwrite ( fd, (void *)var, sizeof(double) * n )
-	 == (int)(sizeof(double) * n) ) return ;
+	 != (int)(sizeof(double) * n) )
-    write_error = true ;
+    {
+        write_error = true ;
+    }
 }
 
 void sgReadBytes ( gzFile fd, const unsigned int n, void *var ) 
 {
-    if ( n == 0)
+    if ( n == 0) return;
-	return;
+    if ( gzread ( fd, var, n ) != (int)n ) {
-    if ( gzread ( fd, var, n ) == (int)n ) 
+        read_error = true ;
-	return ;
+    }
-    read_error = true ;
 }
 
 void sgWriteBytes ( gzFile fd, const unsigned int n, const void *var ) 
 {
-    if ( n == 0)
+    if ( n == 0) return;
-	return;
+    if ( gzwrite ( fd, (void *)var, n ) != (int)n ) {
-    if ( gzwrite ( fd, (void *)var, n ) == (int)n ) 
+        write_error = true ;
-	return ;
+    }
-    write_error = true ;
 }
 
 
 void sgReadUShort ( gzFile fd, const unsigned int n, unsigned short *var )
 {
     if ( gzread ( fd, var, sizeof(unsigned short) * n )
-	 == (int)(sizeof(unsigned short) * n) )
+	 != (int)(sizeof(unsigned short) * n) )
-	return ;
+    {
-    read_error = true ;
+        read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned short int*)var++);
+        }
+    }
 }
 
 
 void sgWriteUShort ( gzFile fd, const unsigned int n, const unsigned short *var )
 {
+    if ( sgIsBigEndian ) {
+        unsigned short *swab = new unsigned short[n];
+        unsigned short *ptr = swab;
+        memcpy( swab, var, sizeof(unsigned short) * n );
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned short*)ptr++);
+        }
+        var = swab;
+    }
     if ( gzwrite ( fd, (void *)var, sizeof(unsigned short) * n )
-	 == (int)(sizeof(unsigned short) * n) )
+	 != (int)(sizeof(unsigned short) * n) )
-	return ;
+    {
-    write_error = true ;
+        write_error = true ;
+    }
 }
 
 
@@ -227,36 +380,68 @@ void sgWriteUShort ( gzFile fd, const unsigned int n, const unsigned short *var
 void sgReadShort ( gzFile fd, const unsigned int n, short *var )
 {
     if ( gzread ( fd, var, sizeof(short) * n )
-	 == (int)(sizeof(short) * n) )
+	 != (int)(sizeof(short) * n) )
-	return ;
+    {
-    read_error = true ;
+        read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned short int*)var++);
+        }
+    }
 }
 
 
 void sgWriteShort ( gzFile fd, const unsigned int n, const short *var )
 {
+    if ( sgIsBigEndian ) {
+        short *swab = new short[n];
+        short *ptr = swab;
+        memcpy( swab, var, sizeof(short) * n );
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned short*)ptr++);
+        }
+        var = swab;
+    }
     if ( gzwrite ( fd, (void *)var, sizeof(short) * n )
-	 == (int)(sizeof(short) * n) )
+	 != (int)(sizeof(short) * n) )
-	return ;
+    {
-    write_error = true ;
+        write_error = true ;
+    }
 }
 
 
 void sgReadUInt ( gzFile fd, const unsigned int n, unsigned int *var )
 {
     if ( gzread ( fd, var, sizeof(unsigned int) * n )
-	 == (int)(sizeof(unsigned int) * n) )
+	 != (int)(sizeof(unsigned int) * n) )
-	return ;
+    {
-    read_error = true ;
+        read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned int*)var++);
+        }
+    }
 }
 
 
 void sgWriteUInt ( gzFile fd, const unsigned int n, const unsigned int *var )
 {
+    if ( sgIsBigEndian ) {
+        unsigned int *swab = new unsigned int[n];
+        unsigned int *ptr = swab;
+        memcpy( swab, var, sizeof(unsigned int) * n );
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned int*)ptr++);
+        }
+        var = swab;
+    }
     if ( gzwrite ( fd, (void *)var, sizeof(unsigned int) * n )
-	 == (int)(sizeof(unsigned int) * n) )
+	 != (int)(sizeof(unsigned int) * n) )
-	return ;
+    {
-    write_error = true ;
+        write_error = true ;
+    }
 }
 
 
@@ -264,18 +449,34 @@ void sgWriteUInt ( gzFile fd, const unsigned int n, const unsigned int *var )
 void sgReadInt ( gzFile fd, const unsigned int n, int *var )
 {
     if ( gzread ( fd, var, sizeof(int) * n )
-	 == (int)(sizeof(int) * n) )
+	 != (int)(sizeof(int) * n) )
-	return ;
+    {
-    read_error = true ;
+        read_error = true ;
+    }
+    if ( sgIsBigEndian ) {
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned int*)var++);
+        }
+    }
 }
 
 
 void sgWriteInt ( gzFile fd, const unsigned int n, const int *var )
 {
+    if ( sgIsBigEndian ) {
+        int *swab = new int[n];
+        int *ptr = swab;
+        memcpy( swab, var, sizeof(int) * n );
+        for ( unsigned int i = 0; i < n; ++i ) {
+            sgEndianSwap( (unsigned int*)ptr++);
+        }
+        var = swab;
+    }
     if ( gzwrite ( fd, (void *)var, sizeof(int) * n )
-	 == (int)(sizeof(int) * n) )
+	 != (int)(sizeof(int) * n) )
-	return ;
+    {
-    write_error = true ;
+        write_error = true ;
+    }
 }
 
 

simgear/io/lowlevel.hxx

@@ -39,6 +39,9 @@
 #include <plib/sg.h>
 
 
+// Note that output is written in little endian form (and converted as
+// necessary)
+
 void sgReadChar ( gzFile fd, char *var ) ;
 void sgWriteChar ( gzFile fd, const char var ) ;
 void sgReadFloat ( gzFile fd, float *var ) ;
@@ -51,6 +54,8 @@ void sgReadInt ( gzFile fd, int *var ) ;
 void sgWriteInt ( gzFile fd, const int var ) ;
 void sgReadLong ( gzFile fd, long int *var ) ;
 void sgWriteLong ( gzFile fd, const long int var ) ;
+void sgReadLongLong ( gzFile fd, long long int *var ) ;
+void sgWriteLongLong ( gzFile fd, const long long int var ) ;
 void sgReadUShort ( gzFile fd, unsigned short *var ) ;
 void sgWriteUShort ( gzFile fd, const unsigned short var ) ;
 void sgReadShort ( gzFile fd, short *var ) ;

simgear/io/socktest.cxx

@@ -1,9 +1,26 @@
 #include <unistd.h>
 
 #include "sg_socket.hxx"
+#include "lowlevel.hxx"
+
+static const int sgEndianTest = 1;
+#define sgIsLittleEndian (*((char *) &sgEndianTest ) != 0)
+#define sgIsBigEndian    (*((char *) &sgEndianTest ) == 0)
 
 int main() {
 
+    if ( sgIsLittleEndian ) {
+       cout << "this machine is little endian\n";
+    }
+
+    if ( sgIsBigEndian ) {
+       cout << "this machine is big endian\n";
+    }
+
+    cout << "short = " << sizeof(unsigned short) << endl;
+    cout << "int = " << sizeof(unsigned int) << endl;
+    cout << "long long = " << sizeof(long long) << endl;
+
     SGSocket s( "", "5500", "tcp" );
 
     if ( !s.open( SG_IO_BI ) ) {