Problem with a macro

[Peter Gregson <pgregson1@xxxxxxxxx>]

Hello,

Perhaps you can help me.  I have a piece of code that I am porting to GCC and one of the macros has been giving me problems for over a week.  Could you please look at it and tell me what is wrong?  Note that this is extracted from the actual code, and is, I think, the smallest amount that shows the problem.


First the code:

/*	Test macro defs		*/

#define __REG16 unsigned short 

#define __READ_WRITE	const

typedef struct {
 __REG16  EA             : 4;
 __REG16  STATTX         : 2;
 __REG16  DTOGTX         : 1;
 __REG16  CTRTX          : 1;
 __REG16  EPKIND         : 1;
 __REG16  EPTYPE         : 2;
 __REG16  SETUP          : 1;
 __REG16  STATRX         : 2;
 __REG16  DTOGRX         : 1;
 __REG16  CTRRX          : 1;
 } __usb_epr_bits;

#define __IO_REG16(NAME, ADDRESS, ATTRIBUTE)             \
     volatile __no_init ATTRIBUTE unsigned short NAME @ ADDRESS 



#define __IO_REG16_BIT(NAME, ADDRESS, ATTRIBUTE,BIT_STRUCT)\
		volatile __no_init  ATTRIBUTE union\
     {unsigned short NAME;				\
      BIT_STRUCT NAME ## _bit;      		\
      } @ ADDRESS



int	main (void) {

	unsigned short USB_EP0R;
	
 __IO_REG16_BIT (USB_EP0R, 0x40005C00,__READ_WRITE,__usb_epr_bits);
 return (0);
 }




Now the error message when I compile it.  Note that I have "--save-temps" in the compiler invocation so that I can see the output of the preprocessor.  I also used -O0 to keep things simple.

Peters-MacBook-Air:STM32F103-STK peter$ gcc -O0 --save-temps -I USB tt.c
tt.c: In function ‘main’:
tt.c:39: error: nested functions are disabled, use -fnested-functions to re-enable
tt.c:39: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘const’
tt.c:39: error: stray ‘@’ in program
tt.c:39: error: expected identifier or ‘(’ before numeric constant
Peters-MacBook-Air:STM32F103-STK peter$ 



When I add -fnested-functions to the command line, I get :

Peters-MacBook-Air:STM32F103-STK peter$ gcc -O0 --save-temps -I USB -fnested-functions tt.c
tt.c: In function ‘main’:
tt.c:39: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘const’
tt.c:39: error: stray ‘@’ in program
tt.c:39: error: expected identifier or ‘(’ before numeric constant
Peters-MacBook-Air:STM32F103-STK peter$ 


The output of the preprocessor is as follows.  You can see that the macro substitution has been carried out, and it appears to my eye, correctly. 

# 1 "tt.c"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "tt.c"
# 9 "tt.c"
typedef struct {
 unsigned short EA : 4;
 unsigned short STATTX : 2;
 unsigned short DTOGTX : 1;
 unsigned short CTRTX : 1;
 unsigned short EPKIND : 1;
 unsigned short EPTYPE : 2;
 unsigned short SETUP : 1;
 unsigned short STATRX : 2;
 unsigned short DTOGRX : 1;
 unsigned short CTRRX : 1;
 } __usb_epr_bits;
# 35 "tt.c"
int main (void) {

unsigned short USB_EP0R;

 volatile __no_init const union {unsigned short USB_EP0R; __usb_epr_bits USB_EP0R_bit; } @ 0x40005C00;

 return (0);
 }


I have the following questions:

1.What are my errors?
2. What is the "@" syntax about?  I think that it means that he union is saved at absolute address 0x40005C00, but when I search on GCC "@" I get nothing.

Can you help me, please?

Thank you, and 

Best regards,

Peter