RE: [avr-gcc-list] Struct problem

[Brian Cuthie]

You can use malloc() to create your buffers and they'll still be globally
accessible so long as the pointers you store them in are global.

-brian 

> -----Original Message-----
> From: Eric Fu [mailto:address@hidden 
> Sent: Friday, January 30, 2004 9:52 PM
> To: address@hidden; address@hidden
> Subject: Re: [avr-gcc-list] Struct problem
> 
> Thanks for the tip.
> The buffers need to be Global, since it needs to be 
> accessible in different modules. My understanding is that 
> malloc is for allocating dynamic memory.
> Anyway, I will read my C book for clue. Thanks for pointing 
> the direction.
> 
> Eric Fu
> 
> 
> ----- Original Message -----
> From: "Brian Cuthie" <address@hidden>
> To: "'Eric Fu'" <address@hidden>; <address@hidden>
> Sent: Saturday, January 31, 2004 12:22 PM
> Subject: RE: [avr-gcc-list] Struct problem
> 
> 
> >
> > The problem, quite simply, is that because the size of TxBuf[] isn't
> > specified, the offset within the struct to RxBuf[] can't be 
> computed at
> > compile time (which it needs to be).
> >
> > To do what you want you'll need to change the struct so 
> that instead of
> > arrays, TxBuf and RxBuf are pointers. Then malloc the 
> memory you need and
> > store the addresses in TxBuf and RxBuf respectively.
> >
> > You might want to re-read a few chapters in your C book.
> >
> > -brian
> >
> > > -----Original Message-----
> > > From: address@hidden
> > > [mailto:address@hidden On Behalf Of Eric Fu
> > > Sent: Friday, January 30, 2004 8:05 PM
> > > To: address@hidden
> > > Subject: [avr-gcc-list] Struct problem
> > >
> > > Hi All,
> > >
> > > I'm trying to declare a Structure for UART, so that it can be
> > > used for more than one UARTs such as:
> > > typedef struct UART
> > > {
> > >  volatile byte RxHead;
> > >  volatile byte RxTail;
> > >  volatile byte TxHead;
> > >  volatile byte TxTail;
> > >  byte TxBuf[],RxBuf[];
> > > }UART;
> > > extern UART uart0;
> > > extern UART uart1;
> > >
> > > By doing this way, I can assign different buffer size to
> > > different UART such as:
> > > byte uart0.RxBuf[RX_BUFFER_SIZE0];
> > > byte uart0.TxBuf[RX_BUFFER_SIZE0];
> > > byte uart1.RxBuf[RX_BUFFER_SIZE1];
> > > byte uart1.TxBuf[RX_BUFFER_SIZE1];
> > >
> > > However, I get the following compile error:
> > > UART.h:47: error: flexible array member not at end of struct
> > >
> > > Could anyone give me a hint on How to tell the compiler 
> to do this?
> > > Thanks
> > >
> > > Eric Fu
> > > _______________________________________________
> > > avr-gcc-list mailing list
> > > address@hidden
> > > http://www.avr1.org/mailman/listinfo/avr-gcc-list
> > >
> >
> >
> 
>