StackOverflow2013

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POC macro for defining symbols
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copied!<p>I'm working with a microcontroller with ANSI C (gcc; not C++) and have a lot of hardware pins to define. I'm looking for a way to make the pin definitions more readable.</p> <p>I think I'd like a macro that would let me define each pin in a single line, like this:</p> <pre><code>PIN(LED_RED, E, 2); PIN(LED_YELLOW, B, 3); PIN(LED_GREEN, A, 4); </code></pre> <p>(this is just a simple example - I've dozens of pins to define). Right now I have ugly looking code like this:</p> <pre><code>#define LED_RED (LATEbits.LATE2) #define LED_RED_TRIS (TRISEbits.TRISE2) #define LED_YELLOW (LATBbits.LATB3) #define LED_YELLOW_TRIS (TRISBbits.TRISB3) #define LED_GREEN (LATAbits.LATA4) #define LED_GREEN_TRIS (TRISAbits.TRISA4) </code></pre> <p>Each pin has 2 symbols; one to read/write the pin, and another to set the I/O direction (the _TRIS definitions). The latch and TRIS definitions come from a header library supplied by the MCU vendor; it's not really practical to avoid using them.</p> <p>I'm fairly sure it is possible to write a macro in C that will define both symbols, but I'm not very good with the # and ## stuff. Here is my half-baked attempt (doesn't work): </p> <pre><code>#define _PIN( id,port,pos) #define ##id (LAT ##port ##bits.LAT ##port ##pos ) #define _TRIS(id,port,pos) #define ##id _TRIS (TRIS ##port ##bits .TRIS ##port ##pos ) #define PIN( id,port,pos) _PIN(id,port,pos) _TRIS(id,port,pos) </code></pre> <p>Is there a way to do this? </p> <p>Or, is there another way to simplify my pin definitions? I'd like to get it down to one line/pin, and to get rid of the duplication of port id (A,B,C, etc.) and bit number (2,3,4, etc.) that I have now; putting them in twice is just asking for trouble.</p> <p>Cheers,</p> <p>--Dave</p>

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