🚀 go-pugleaf

karl@haddock.ima.isc.com (Karl Heuer) writes:
>[`copybit' should generate a simple move-bit instruction]
>[I wanted to write]
>	unsigned int copybit(unsigned int x) {
>		if (x & 0x10) x |= 0x40; else x &= ~0x40;
>		return (x);
>	}
>[Suggesting:]
>	typedef struct { unsigned int :4, src:1, :1, dst:1; } hack;
>	unsigned int copybit(unsigned int x) {
>		escape(x, hack).dst = escape(x, hack).src;
>	}
>[Yes, I'm aware of the portability problems.]

In cases such as this, GNU CC provides another solution: typed
asm's that take variables as arguments.  If you care, you can
even put this function in to your .h file, qualify it with
`inline', and away you go!

#ifdef __GNUC__
	unsigned int
    copybit (unsigned int x)
    {
    #ifdef __vax__
	asm ("mumble %0,%1" : "=r" (x) : "0" (x));
    #elseif defined (__machine__)
	...
    #else
	{ NEED A MACHINE TYPE! }	/* Compile-time error. */
    #endif
	return (x);
    }
#else
	unsigned int
    copybit (..) {...}
#endif

		;-D on  ( A void* warranty )  Pardo
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