[R-gregmisc-users] SF.net SVN: r-gregmisc: [1144] trunk/SASxport/src/reverse.c

[<wa...@us...>]

Revision: 1144
          http://r-gregmisc.svn.sourceforge.net/r-gregmisc/?rev=1144&view=rev
Author:   warnes
Date:     2007-08-14 23:04:57 -0700 (Tue, 14 Aug 2007)

Log Message:
-----------
Restore reverse.c

Added Paths:
-----------
    trunk/SASxport/src/reverse.c

Copied: trunk/SASxport/src/reverse.c (from rev 1136, trunk/SASxport/src/reverse.c)
===================================================================
--- trunk/SASxport/src/reverse.c	                        (rev 0)
+++ trunk/SASxport/src/reverse.c	2007-08-15 06:04:57 UTC (rev 1144)
@@ -0,0 +1,83 @@
+#include "writeSAS.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#import  <assert.h>
+#import  <sys/types.h>
+
+/* reverse: convert current byte order to little endian */
+void reverse( u_char *intp, size_t size)
+{
+  static u_char endianTest[2] =   {0x01,0x00};
+  size_t i;
+  u_char tmp;
+
+#if !defined(BIG_ENDIAN) && !defined(LITTLE_ENDIAN)
+  /* Test if we are on a big endian or little endian platform */
+  if( (short) *endianTest == 1 ) 
+    {  
+      /* Little Endian */
+      /* Do nothing    */
+      return;  
+    }
+#endif
+
+  /* Big Endian */
+  /* Swap bytes */
+  for(i=0; i < size/2; i++)
+    {
+      tmp = (u_char) intp[i];
+      intp[i] = intp[size-i-1];
+      intp[size-i] = tmp;
+    }
+  
+  return;
+}
+
+
+/* test code */
+void test_reverse()
+{
+  u_char  byte_pattern[1] = { 0x00 };
+  u_char  byte_value      = 0x00;
+  
+  u_char  short_pattern[2] = { 0x00, 0x01 };  /* NB: little endian byte pattern */
+  short   short_value       = 0x0100;          /* NB: hex is written big endian */
+  
+  u_char  int_pattern[4]   = { 0x0, 0x01, 0x02, 0x03 };
+  int     int_value        = 0x03020100; 
+
+  u_char  long_pattern[4]  = { 0x0, 0x01, 0x02, 0x03 };
+  long    long_value       = 0x03020100; 
+
+  /* Do the reverse, then test */
+
+  /* byte */
+  REVERSE( &byte_value, sizeof(u_char) );
+  assert( (u_char) *byte_pattern == byte_value );
+
+  /* short */
+  REVERSE( &short_value, sizeof(short) );
+  assert( *((short *) short_pattern) == short_value );
+
+  /* int */
+  REVERSE( &int_value, sizeof(int) );
+  assert( *((int *) int_pattern) == int_value );
+
+  /* long */
+  REVERSE( &long_value, sizeof(long) );
+  assert( *((long*) long_pattern) == long_value );
+
+}
+
+
+#ifdef DO_TEST
+int main(int argc, u_char *argv)
+{
+  test_reverse();
+}
+
+
+
+#endif


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