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[avr-libc-dev] Determine defined port

From: Harald Kipp
Subject: [avr-libc-dev] Determine defined port
Date: Sun, 22 Aug 2004 17:46:37 +0200

Hi all,

I stumbled over the following pre-processor problem.

Somewhere in an include file there's a macro

  #define MY_PORT  PORTC

User's should be able to adapt the program to their hardware
be simply changing this include file.

To make the code independent from the specified port,
I need something like

  #if (MY_PORT == PORTC)
  /* Do something PORTC specific, like disabling XMEM */
  sbi(MY_PORT, 7);

Obviously this won't work, because PORTC is an already dereferenced
volatile pointer. No chance to retrieve the pointer address, right?

I could enumerate the ports by

  #define GPIO_A  1
  #define GPIO_C  3

... and replace the macro MY_PORT in the configuration header by

  /* Please use GPIO_A for PORTA, GPIO_B for PORTB etc. */
  #define MY_GPIO GPIO_C

and further define

  #if (MY_GPIO == GPIO_C)
  #define MY_PORT  PORTC

for any port available, so finally

  /* GPIO_C refers to PORTC */
  #if (MY_GPIO == GPIO_C)
  /* Do something PORTC specific, like disabling XMEM */
  sbi(MY_PORT, 7);

will give the expected result. Any ideas for a simpler and less
confusing method?

Thanks for your time,


P.S.: I just recognized I sent an empty message to this list some time
ago. I'm sorry for that.

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