Owen Edwards
/
TwosComplement
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Diff: SignExtend.cpp
- Revision:
- 0:b495118be5a7
diff -r 000000000000 -r b495118be5a7 SignExtend.cpp
--- /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;
+}