C to C# conversion of #define macros

Question

Hi,

How would you go about converting the following C #define into c#.

        #define get16bits(d) (*((const uint16_t *) (d)))
        #if !defined (get16bits)
        #define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
                  +(uint32_t)(((const uint8_t *)(d))[0]) )
        #endif

I know you probably replace the uint32_t which with UInt32 change the other types to c# equivalent, but how proceed from making the above a static method. Would that be the best way of going about it.

Bob.

Answer 1

I do not know why you are checking to see if get16bits is defined immediately after you define it, as the only way it would not be is a preprocessor error which would stop your compile.

Now, that said, here's how you translate that godawful macro to C#:

aNumber & 0xFFFF;

In fact, here's how you translate that macro to C:

a_number & 0xFFFF;

You don't need all this casting wizardry just to get the lower 16 bits of a number. Here's more C defines to show you what I'm talking about:

#define   getbyte(d)     (d & 0xFF)
#define   getword(d)     (d & 0xFFFF)
#define   getdword(d)    (d & 0xFFFFFFFF)
#define   gethighword(d) ((d & 0xFFFF0000) >> 16)
#define   gethighbyte(d) ((d & 0xFF00) >> 8)

Have you really used that macro in production code?

Answer 2

Getting the lower 16 bits of an integer is quite easy in C#:

int x = 0x12345678;
short y = (short)x; // gets 0x5678

If you want a static method for doing it, it's just as simple:

public static short Get16Bits(int value) {
   return (short)value;
}