Try this:
struct
{
uint8_t *tx_head;
uint8_t volatile *tx_tail;
uint8_t tx_buffer[DBG_BUF_SZ];
/* blah blah */
uint8_t dbg_timer;
} dbg_serial_port;
Declare the pointer volatile, not the value it is pointing to
Pink Boy wrote:
Hi,
I recently run into an issue with a struct with some volatile members and
was wondering is this is a problem with me or gcc, ar avr-gcc.
I have a structure used to define a buffer for a serial port somewhat like
this.
struct
{
uint8_t *tx_head;
volatile uint8_t *tx_tail;
uint8_t tx_buffer[DBG_BUF_SZ];
/* blah blah */
uint8_t dbg_timer;
} dbg_serial_port;
In my main loop I have a code that waits to see if the buffer is full.
while(dbg_serial_port.tx_head == dbg_serial_port.txtail)
;
And of course with compiler flags set to optimize for size -Os it hangs
and waits forever.
The only way to get it to work is to declare the whole structure and
tx_tail as volatile. I'd be just annoyed, but if I do that I get a whole
bunch of compiler warnings on stuff like
uint8_t *temp = dbg_serial_port.tx_head;
I can fix those with a cast but doing that is like going after a fly
with a hammer.
Is this a bug with gcc's handling of volatile or just me?
PS: Using the WinAvr 20090313.
Matt
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