re-entrant function in Keil-4 RVMDK
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From: kishor on 1 Jun 2010 04:17 Thanks for reply, > You make a function re-entrant by writing appropriate C code - avoid > using shared storage (such as global variables or function-scope > statics), avoid calling non-re-entrant functions, etc. > I have written some "Ring buffer" operation related function. Byte FIFO_Write (ST_RING_BUFF * lpstBuff, Byte lbData); Byte Read_Buff (ST_RING_BUFF * lpstBuff); In above functions I am passing pointer to ring buffer structure, passing or receiving data Byte. I have two ring buffers for two serial ports. In following case, If FIFO_Write function is writing data to first Buffer. At the same time if Second serial port ISR interrupts the function. And if it calls the FIFO_Write function, to write data to second buffer. Is it safe to use these 'common' functions for both the serial port buffer? Regards, Kishore.
From: David Brown on 1 Jun 2010 07:08
On 01/06/2010 10:17, kishor wrote: > Thanks for reply, > >> You make a function re-entrant by writing appropriate C code - avoid >> using shared storage (such as global variables or function-scope >> statics), avoid calling non-re-entrant functions, etc. >> > I have written some "Ring buffer" operation related function. > > Byte FIFO_Write (ST_RING_BUFF * lpstBuff, Byte lbData); > Byte Read_Buff (ST_RING_BUFF * lpstBuff); > > In above functions I am passing pointer to ring buffer structure, > passing or receiving data Byte. > > I have two ring buffers for two serial ports. > > In following case, > If FIFO_Write function is writing data to first Buffer. > At the same time if Second serial port ISR interrupts the function. > And if it calls the FIFO_Write function, to write data to second > buffer. > > Is it safe to use these 'common' functions for both the serial port > buffer? > Yes, of course it is safe. This is basic C knowledge. I think perhaps you have been corrupted by working with a hideous compiler* for a hideous chip that can't work with proper C. You may have to read a book on C programming, and you will certainly have to /think/ a bit about what you are writing, how it works, and how it is implemented. Some trial and error, test code, and studying generated assembly code would also help. * Keil may be the best compiler available for the 8051, but it is hideous nonetheless. |