🚀 go-pugleaf

In article <iwXX9.1384$Xh6.582263850@newssvr13.news.prodigy.com>,
 "Raymond" <ray@n0.sp4m.powerproduction.n0.sp4m.com> wrote:

>Jason
>
>I had a similar problem and MW support tried to pacify me by saying I was
>doing something wrong, and finally blew me off.
>-- (MWRon, see: MW Tech support # 1-28735400)

I looked into this and support thought that you had understood the 
question.  Here is a fuller description of why this is not an error and 
your code is non conformant.

Ron

   a left shift, can only operate in the context of the bits in the
   part being shifted. So shifting a 32-bit value by a value of 32
   or greater is undefined in the language standard.

   a constant like 5, is an int and will not get promoted to
   a "long long" or "unsigned long long" unless the code explicitly
   uses the long long (or unsigned long long) form of the constant:

   5LL or 5ULL

   or if there is an explicit type casting:

   (long long) 5 or (unsigned long long) 5

   When assigning a computation to a variable the implicit type convert
   happens after the expression is evaluated.

   so on PowerPC:

   (5 << 32) | (32777)

   produces either: 0x8009 or 0x800d

   In the first case the IR optimizer treated the undefined value
   as 0 (5 << 32) == 0. In the second case the code generator ANDed
   the shift amount with 31 such that (5 << 32) becomes (5 << 0) == 5.

   It will never produce 0x500008009, and even then the example
   is wrong as 0x500008009 & 0xFFFF000000000000 produces 0.

   Neither behavior will produce the results expected by the code 
example:

   void  main ( void )
   {
      UInt64 value;

      value =  ( ( 5 << 32 ) | ( 32777 ) );
      Routine_1( value );
   }

   void  Routine_1 ( UInt64 value )
   {
      Routine_2( value );
   }

   void  Routine_2 ( UInt64 value )
   {
      if( value & 0xFFFF000000000000 )
      {
         return; //no problems
      }
      else
      {
         complain(__LINE__);
      }
   }


therefore your code must be written like:

   void  main ( void )
   {
      UInt64 value;

      value =  ( ( ((UInt64)5) << 32 ) | ( 32777 ) );
      Routine_1( value );
   }

   void  Routine_1 ( UInt64 value )
   {
      Routine_2( value );
   }

   void  Routine_2 ( UInt64 value )
   {
      if( value & 0xFFFFFFFF00000000 )
      {
         return; //no problems
      }
      else
      {
         complain(__LINE__);
      }
   }

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Ron Liechty - MWRon@metrowerks.com - http://www.metrowerks.com