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Need idea for io bit field macro

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firmware

Posted: Nov 18, 2009 - 03:47 PM

Joined: Jun 05, 2007
Posts: 193

hi all,

Currently I'm using bit field style for I/O and I'm making the definitions of I/O bit field as below.

Code:

typedef struct {

   unsigned char   b0:1;

   unsigned char   b1:1;

   unsigned char   b2:1;

   unsigned char   b3:1;

   unsigned char   b4:1;

   unsigned char   b5:1;

   unsigned char   b6:1;

   unsigned char   b7:1;

} bit_field;

typedef union {

   unsigned char   byte;

   bit_field      bit;

} io_reg;

#define      ioPORTB    ((volatile io_reg*)&PORTB)->byte

#define      ioPORTB0   ((volatile io_reg*)&PORTB)->bit.b0

#define      ioPORTB1   ((volatile io_reg*)&PORTB)->bit.b1

#define      ioPORTB2   ((volatile io_reg*)&PORTB)->bit.b2

#define      ioPORTB3   ((volatile io_reg*)&PORTB)->bit.b3

#define      ioPORTB4   ((volatile io_reg*)&PORTB)->bit.b4

#define      ioPORTB5   ((volatile io_reg*)&PORTB)->bit.b5

#define      ioPORTB6   ((volatile io_reg*)&PORTB)->bit.b6

#define      ioPORTB7   ((volatile io_reg*)&PORTB)->bit.b7

#define      ioPORTC    ((volatile io_reg*)&PORTC)->byte

#define      ioPORTC0   ((volatile io_reg*)&PORTC)->bit.b0

#define      ioPORTC1   ((volatile io_reg*)&PORTC)->bit.b1

#define      ioPORTC2   ((volatile io_reg*)&PORTC)->bit.b2

#define      ioPORTC3   ((volatile io_reg*)&PORTC)->bit.b3

#define      ioPORTC4   ((volatile io_reg*)&PORTC)->bit.b4

#define      ioPORTC5   ((volatile io_reg*)&PORTC)->bit.b5

#define      ioPORTC6   ((volatile io_reg*)&PORTC)->bit.b6

#define      ioPORTC7   ((volatile io_reg*)&PORTC)->bit.b7

Usage

Code:

ioPORTB  = 0xff;

ioPORTC0 = 1;

But I would like to making some macro that able to fill in a name and address of I/O bit field for instead of above definitions. But same usage.

Code:

#define  SOME_MACRO(__NAME,  __ADDR) \

------------------------------------------------------\

------------------------------------------------------\

------------------------------------------------------\

------------------------------------------------------\

SOME_MACRO(ioPORTB, &PORTB);

SOME_MACRO(ioPORTB, &PORTC);

Any someone guide me for achieve this macro ?

Regards,

clawson

Posted: Nov 18, 2009 - 03:52 PM

Joined: Jul 18, 2005
Posts: 33138
Location: (using avr-gcc in) Finchingfield, Essex, England

But what does such a macro really buy you? As far as I know no AVR has a port above PORTL so the worst case is you have to Ctrl-C/Ctrl-V/Ctrl-H one of those blocks 12 times? You do this once in your life and you have a header file that is good for all time. Just wrap each block in (for example):

Code:

#ifdef PORTG

#define      ioPORTG    ((volatile io_reg*)&PORTG)->byte 

#define      ioPORTG0   ((volatile io_reg*)&PORTG)->bit.b0 

#define      ioPORTG1   ((volatile io_reg*)&PORTG)->bit.b1 

#define      ioPORTG2   ((volatile io_reg*)&PORTG)->bit.b2 

#define      ioPORTG3   ((volatile io_reg*)&PORTG)->bit.b3 

#define      ioPORTG4   ((volatile io_reg*)&PORTG)->bit.b4 

#define      ioPORTG5   ((volatile io_reg*)&PORTG)->bit.b5 

#define      ioPORTG6   ((volatile io_reg*)&PORTG)->bit.b6 

#define      ioPORTG7   ((volatile io_reg*)&PORTG)->bit.b7 

#endif

(I just used Ctrl-H and changed PORTB to PORTG in that)

In fact you don't even need the #ifdef - just don't use a "G" entry on an AVR that doesn't have PORTG

_________________

firmware

Posted: Nov 18, 2009 - 04:03 PM

Joined: Jun 05, 2007
Posts: 193

Currently I'm using this idea already.

Code:

#ifdef PORTG 

#define      ioPORTG    ((volatile io_reg*)&PORTG)->byte 

#define      ioPORTG0   ((volatile io_reg*)&PORTG)->bit.b0 

#define      ioPORTG1   ((volatile io_reg*)&PORTG)->bit.b1 

#define      ioPORTG2   ((volatile io_reg*)&PORTG)->bit.b2 

#define      ioPORTG3   ((volatile io_reg*)&PORTG)->bit.b3 

#define      ioPORTG4   ((volatile io_reg*)&PORTG)->bit.b4 

#define      ioPORTG5   ((volatile io_reg*)&PORTG)->bit.b5 

#define      ioPORTG6   ((volatile io_reg*)&PORTG)->bit.b6 

#define      ioPORTG7   ((volatile io_reg*)&PORTG)->bit.b7 

#endif

But I plan for use the macro for more registers not only I/O.

glitch

Posted: Nov 18, 2009 - 04:04 PM

Joined: Jan 12, 2002
Posts: 6972
Location: Canada

it is not possible to have a single macro generate multiple identifiers.

If your compiler allows for anonymous structures & unions, you could use that feature to create what you want, because the member names will be promoted up in scope to the containing non-anonymous block. [I'm not sure if GCC offers this or not, it is non-standard behaviour]

IAR does this with a chain of macros that essentially create the union in place, with the desired names. The union itself is anonymous, thus the bit fields end up being promoted to the global scope.

Code:

#define __BYTEBITS(_NAME,_A,_B,_C,_D,_E,_F,_G,_H) \

unsigned char _NAME ## _ ## _A:1, \

              _NAME ## _ ## _B:1, \

              _NAME ## _ ## _C:1, \

              _NAME ## _ ## _D:1, \

              _NAME ## _ ## _E:1, \

              _NAME ## _ ## _F:1, \

              _NAME ## _ ## _G:1, \

              _NAME ## _ ## _H:1;

#define SFR_B_BITS(_NAME, _ADDR, _A,_B,_C,_D,_E,_F,_G,_H) \

    __io union { \

      unsigned char   _NAME;   /* The sfrb as 1 byte */ \

      struct {                 /* The sfrb as 8 bits */ \

        __BYTEBITS(_NAME, _A,_B,_C,_D,_E,_F,_G,_H) \

      };  \

    } @ _ADDR;

#define SFR_B(_NAME, _ADDR) SFR_B_BITS(_NAME, _ADDR,\ 

                                    Bit0,Bit1,Bit2,Bit3,Bit4,Bit5,Bit6,Bit7)

SFR_B(PINF,   0x00)     /* Input Pins, Port F */

this is from an old version of IAR, the newer versions do it slightly differently.

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