Re: [avr-gcc-list] How to pass a struct in Interrupt

[Eric Fu]

Thanks for the tips. It works greatly. I'm confidant about the ' external'
stuff now.

Eric Fu
----- Original Message ----- 
From: "David Brown" <address@hidden>
To: <address@hidden>
Sent: Friday, January 16, 2004 9:56 PM
Subject: Re: [avr-gcc-list] How to pass a struct in Interrupt


>
> It looks like you have got your header files mixed up, so when compiling
> isr.c there is no definition of the UART structure.  Since UART is an
> unknown type, the compiler guesses (with an error message) that it is an
> "int", and everything goes downhill from there.
>
>
> The most common way to arrange something like this is:
>
> /* uart.h */
> typedef struct { ...} UART;
> extern UART uart0;
>
> /* uart.c */
> #include "uart.h"
> UART uart0;
>
> /* isr.c */
> #include "uart.h"
> SIGNAL(SIG_UART_RECV) ...
>
>
> Any "extern" in a ".c" file is almost always a sign of confused .h/.c
module
> interface definition (except for occasional quick-and-dirty test code
added
> to existing code).
>
>
>
>
>
>
>
> ----- Original Message -----
> From: "Eric Fu" <address@hidden>
> To: <address@hidden>
> Sent: Friday, January 16, 2004 11:22 AM
> Subject: [avr-gcc-list] How to pass a struct in Interrupt
>
>
> Hi,
>
> I'm trying to write a simple Interrupt driven UART.
>
> I defined a struct  in UART.c like:
> typedef struct UART
> {
>  byte RxBuf[RX_BUFFER_SIZE];
>  volatile byte RxHead;
>  volatile byte RxTail;
>     .
>     .
>
>  }UART;
>
> UART uart0;
>
> And in isr.c, I declare and define:
> extern UART uart0;
> SIGNAL(SIG_UART_RECV) //USART RX complete INT
> {
>  byte data;
>  byte tmphead;
>
>  /* Read the received data */
>  data = UDR;
>  /* Calculate buffer index */
>  tmphead = ( uart0.RxHead + 1 ) & RX_BUFFER_MASK;
>  uart0.RxHead = tmphead;      /* Store new index */
>     .
>     .
> }
>
> I have the following compile error:
> Compiling: isr.c
>
avr-gcc -c -mmcu=atmega16 -I. -g -Os -funsigned-char -funsigned-bitfields -f
>
pack-struct -fshort-enums -Wall -Wstrict-prototypes -Wa,-adhlns=isr.lst -Ic:
> /pjt2/avr/PJT_inc -std=gnu99 isr.c -o isr.o
> isr.c:17: error: parse error before "uart0"
> isr.c:17: warning: type defaults to `int' in declaration of `uart0'
> isr.c:17: warning: data definition has no type or storage class
> isr.c: In function `__vector_11':
> isr.c:84: error: request for member `RxHead' in something not a structure
or
> union
> isr.c:85: error: request for member `RxHead' in something not a structure
or
> union
> isr.c:87: error: request for member `RxTail' in something not a structure
or
> union
> isr.c:92: error: request for member `RxBuf' in something not a structure
or
> union
> isr.c: In function `__vector_12':
> isr.c:104: error: request for member `TxHead' in something not a structure
> or union
> isr.c:104: error: request for member `TxTail' in something not a structure
> or union
> isr.c:107: error: request for member `TxTail' in something not a structure
> or union
> isr.c:108: error: request for member `TxTail' in something not a structure
> or union
> isr.c:110: error: request for member `TxBuf' in something not a structure
or
> union
> make: *** [isr.o] Error 1
>
> It seems the compiler doesn't recognise an external struct definition.
Could
> anyone give me a hint to get around this?
> Thanks.
>
> Eric Fu
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>
>
>
>
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