Owen Edwards / TwosComplement

Handle two\'s complement numbers.

Diff: SignExtend.cpp

Revision:
0:b495118be5a7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SignExtend.cpp	Thu Jan 20 20:01:36 2011 +0000
@@ -0,0 +1,17 @@
+#include "mbed.h"
+#include "assert.h"
+
+int SignExtend( int value, const int bit_width )
+{
+    assert( ( bit_width > 1) && ( bit_width < (8*sizeof(int)) ) );
+
+    value &= ( (1<<(bit_width)) - 1 ); /* Clear out any extra MSB data */
+
+    if ( ( value & ( 1 << (bit_width-1) ) ) != 0 )
+    {
+        /* value IS negative */
+        value -= (1<<bit_width);
+    }
+
+    return value;
+}