Is there a way to create a C #define macro such that a call to it: nop_delay(5) would yield the following expanded code?: _nop()_; _nop()_; _nop()_; _nop()_; _nop()_; Thanks, Tom
Jon Ward posted a nice trick in the thread: http://www.keil.com/forum/docs/thread1940.asp
#define NOPS(x) \ (((x) & 1) ? _nop_() : 0), \ (((x) & 2) ? _nop_(),_nop_() : 0), \ (((x) & 4) ? _nop_(),_nop_(),_nop_(),_nop_() : 0), \ (((x) & 8) ? _nop_(),_nop_(),_nop_(),_nop_(),_nop_(),_nop_(),_nop_(),_nop_() : 0)
Drew, Thanks a bunch. That was exactly what I was looking for. -Tom
Hi, I'm using already for quite some time the following macro construction, but it finally boils down to what Jon gave as an example: #define USEC() _nop_() #define DELAY2() ( USEC() , USEC() ) #define DELAY4() ( DELAY2() , DELAY2() ) #define DELAY8() ( DELAY4() , DELAY4() ) #define DELAY16() ( DELAY8() , DELAY8() ) #define DELAY32() ( DELAY16(), DELAY16() ) #define DELAY64() ( DELAY32(), DELAY32() ) #define DELAY128() ( DELAY64(), DELAY64() ) #define DELAY(T) ( ( T & 1 ) ? USEC() :0 ), \ ( ( T & 2 ) ? DELAY2() :0 ), \ ( ( T & 4 ) ? DELAY4() :0 ), \ ( ( T & 8 ) ? DELAY8() :0 ), \ ( ( T & 16 ) ? DELAY16() :0 ), \ ( ( T & 32 ) ? DELAY32() :0 ), \ ( ( T & 64 ) ? DELAY64() :0 ), \ ( ( T & 128 ) ? DELAY128() :0 ) \ To use it, I simply ask for e.g. DELAY( 27 ) and the rest is done automatically. The only difference is that you don't have to type so much _nop_()'s every time and you might have a better overview. Keep in mind that I wrote it for a 8051, running on 12 Mc, hence the following equation:
#define USEC() _nop_() #define DELAY2() ( USEC() , USEC() ) #define DELAY4() ( DELAY2() , DELAY2() ) #define DELAY8() ( DELAY4() , DELAY4() ) #define DELAY16() ( DELAY8() , DELAY8() ) #define DELAY32() ( DELAY16(), DELAY16() ) #define DELAY64() ( DELAY32(), DELAY32() ) #define DELAY128() ( DELAY64(), DELAY64() ) #define DELAY(T) ( ( T & 1 ) ? USEC() :0 ), \ ( ( T & 2 ) ? DELAY2() :0 ), \ ( ( T & 4 ) ? DELAY4() :0 ), \ ( ( T & 8 ) ? DELAY8() :0 ), \ ( ( T & 16 ) ? DELAY16() :0 ), \ ( ( T & 32 ) ? DELAY32() :0 ), \ ( ( T & 64 ) ? DELAY64() :0 ), \ ( ( T & 128 ) ? DELAY128() :0 ) \
#define USEC _nop_()