364 lines
8.9 KiB
C
364 lines
8.9 KiB
C
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/**
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* \file
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* <!--
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* This file is part of BeRTOS.
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*
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* Bertos is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* As a special exception, you may use this file as part of a free software
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* library without restriction. Specifically, if other files instantiate
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* templates or use macros or inline functions from this file, or you compile
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* this file and link it with other files to produce an executable, this
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* file does not by itself cause the resulting executable to be covered by
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* the GNU General Public License. This exception does not however
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* invalidate any other reasons why the executable file might be covered by
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* the GNU General Public License.
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*
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* Copyright 2003, 2004 Develer S.r.l. (http://www.develer.com/)
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* Copyright 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
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* -->
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*
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* \defgroup fifobuf FIFO buffer
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* \ingroup struct
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* \{
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*
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* \brief General pourpose FIFO buffer implemented with a ring buffer
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*
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* \li \c begin points to the first buffer element;
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* \li \c end points to the last buffer element (unlike the STL convention);
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* \li \c head points to the element to be extracted next;
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* \li \c tail points to the location following the last insertion;
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* \li when any of the pointers advances beyond \c end, it is reset
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* back to \c begin.
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*
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* \code
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*
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* +-----------------------------------+
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* | empty | valid data | empty |
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* +-----------------------------------+
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* ^ ^ ^ ^
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* begin head tail end
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*
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* \endcode
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*
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* The buffer is EMPTY when \c head and \c tail point to the same location:
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* \code head == tail \endcode
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*
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* The buffer is FULL when \c tail points to the location immediately
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* after \c head:
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* \code tail == head - 1 \endcode
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*
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* The buffer is also FULL when \c tail points to the last buffer
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* location and head points to the first one:
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* \code head == begin && tail == end \endcode
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*
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* \author Bernie Innocenti <bernie@codewiz.org>
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*/
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#ifndef STRUCT_FIFO_H
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#define STRUCT_FIFO_H
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#include <cpu/types.h>
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#include <cpu/irq.h>
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#include <cfg/debug.h>
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typedef struct FIFOBuffer
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{
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unsigned char * volatile head;
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unsigned char * volatile tail;
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unsigned char *begin;
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unsigned char *end;
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} FIFOBuffer;
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#define ASSERT_VALID_FIFO(fifo) \
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ATOMIC( \
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ASSERT((fifo)->head >= (fifo)->begin); \
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ASSERT((fifo)->head <= (fifo)->end); \
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ASSERT((fifo)->tail >= (fifo)->begin); \
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ASSERT((fifo)->tail <= (fifo)->end); \
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)
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/**
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* Check whether the fifo is empty
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*
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* \note Calling fifo_isempty() is safe while a concurrent
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* execution context is calling fifo_push() or fifo_pop()
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* only if the CPU can atomically update a pointer
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* (which the AVR and other 8-bit processors can't do).
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*
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* \sa fifo_isempty_locked
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*/
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INLINE bool fifo_isempty(const FIFOBuffer *fb)
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{
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//ASSERT_VALID_FIFO(fb);
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return fb->head == fb->tail;
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}
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/**
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* Check whether the fifo is full
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*
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* \note Calling fifo_isfull() is safe while a concurrent
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* execution context is calling fifo_pop() and the
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* CPU can update a pointer atomically.
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* It is NOT safe when the other context calls
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* fifo_push().
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* This limitation is not usually problematic in a
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* consumer/producer scenario because the
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* fifo_isfull() and fifo_push() are usually called
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* in the producer context.
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*/
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INLINE bool fifo_isfull(const FIFOBuffer *fb)
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{
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//ASSERT_VALID_FIFO(fb);
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return
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((fb->head == fb->begin) && (fb->tail == fb->end))
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|| (fb->tail == fb->head - 1);
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}
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/**
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* Push a character on the fifo buffer.
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*
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* \note Calling \c fifo_push() on a full buffer is undefined.
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* The caller must make sure the buffer has at least
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* one free slot before calling this function.
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*
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* \note It is safe to call fifo_pop() and fifo_push() from
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* concurrent contexts, unless the CPU can't update
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* a pointer atomically (which the AVR and other 8-bit
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* processors can't do).
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*
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* \sa fifo_push_locked
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*/
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INLINE void fifo_push(FIFOBuffer *fb, unsigned char c)
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{
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#ifdef __MWERKS__
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#pragma interrupt called
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#endif
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//ASSERT_VALID_FIFO(fb);
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/* Write at tail position */
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*(fb->tail) = c;
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if (UNLIKELY(fb->tail == fb->end))
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/* wrap tail around */
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fb->tail = fb->begin;
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else
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/* Move tail forward */
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fb->tail++;
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}
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/**
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* Pop a character from the fifo buffer.
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*
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* \note Calling \c fifo_pop() on an empty buffer is undefined.
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* The caller must make sure the buffer contains at least
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* one character before calling this function.
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*
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* \note It is safe to call fifo_pop() and fifo_push() from
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* concurrent contexts.
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*/
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INLINE unsigned char fifo_pop(FIFOBuffer *fb)
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{
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#ifdef __MWERKS__
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#pragma interrupt called
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#endif
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//ASSERT_VALID_FIFO(fb);
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if (UNLIKELY(fb->head == fb->end))
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{
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/* wrap head around */
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fb->head = fb->begin;
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return *(fb->end);
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}
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else
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/* move head forward */
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return *(fb->head++);
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}
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/**
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* Make the fifo empty, discarding all its current contents.
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*/
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INLINE void fifo_flush(FIFOBuffer *fb)
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{
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//ASSERT_VALID_FIFO(fb);
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fb->head = fb->tail;
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}
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#if CPU_REG_BITS >= CPU_BITS_PER_PTR
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/*
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* 16/32bit CPUs that can update a pointer with a single write
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* operation, no need to disable interrupts.
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*/
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#define fifo_isempty_locked(fb) fifo_isempty((fb))
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#define fifo_push_locked(fb, c) fifo_push((fb), (c))
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#define fifo_pop_locked(fb) fifo_pop((fb))
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#define fifo_flush_locked(fb) fifo_flush((fb))
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#else /* CPU_REG_BITS < CPU_BITS_PER_PTR */
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/**
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* Similar to fifo_isempty(), but with stronger guarantees for
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* concurrent access between user and interrupt code.
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*
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* \note This is actually only needed for 8-bit processors.
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*
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* \sa fifo_isempty()
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*/
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INLINE bool fifo_isempty_locked(const FIFOBuffer *fb)
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{
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bool result;
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ATOMIC(result = fifo_isempty(fb));
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return result;
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}
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/**
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* Similar to fifo_push(), but with stronger guarantees for
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* concurrent access between user and interrupt code.
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*
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* \note This is actually only needed for 8-bit processors.
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*
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* \sa fifo_push()
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*/
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INLINE void fifo_push_locked(FIFOBuffer *fb, unsigned char c)
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{
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ATOMIC(fifo_push(fb, c));
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}
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/* Probably not really needed, but hard to prove. */
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INLINE unsigned char fifo_pop_locked(FIFOBuffer *fb)
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{
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unsigned char c;
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ATOMIC(c = fifo_pop(fb));
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return c;
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}
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/**
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* Similar to fifo_flush(), but with stronger guarantees for
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* concurrent access between user and interrupt code.
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*
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* \note This is actually only needed for 8-bit processors.
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*
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* \sa fifo_flush()
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*/
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INLINE void fifo_flush_locked(FIFOBuffer *fb)
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{
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ATOMIC(fifo_flush(fb));
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}
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#endif /* CPU_REG_BITS < BITS_PER_PTR */
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/**
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* Thread safe version of fifo_isfull()
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*/
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INLINE bool fifo_isfull_locked(const FIFOBuffer *_fb)
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{
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bool result;
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ATOMIC(result = fifo_isfull(_fb));
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return result;
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}
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/**
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* FIFO Initialization.
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*/
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INLINE void fifo_init(FIFOBuffer *fb, unsigned char *buf, size_t size)
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{
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/* FIFO buffers have a known bug with 1-byte buffers. */
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ASSERT(size > 1);
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fb->head = fb->tail = fb->begin = buf;
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fb->end = buf + size - 1;
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}
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/**
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* \return Lenght of the FIFOBuffer \a fb.
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*/
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INLINE size_t fifo_len(FIFOBuffer *fb)
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{
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return fb->end - fb->begin;
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}
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#if 0
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/*
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* UNTESTED: if uncommented, to be moved in fifobuf.c
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*/
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void fifo_pushblock(FIFOBuffer *fb, unsigned char *block, size_t len)
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{
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size_t freelen;
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/* Se c'e' spazio da tail alla fine del buffer */
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if (fb->tail >= fb->head)
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{
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freelen = fb->end - fb->tail + 1;
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/* C'e' abbastanza spazio per scrivere tutto il blocco? */
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if (freelen < len)
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{
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/* Scrivi quello che entra fino alla fine del buffer */
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memcpy(fb->tail, block, freelen);
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block += freelen;
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len -= freelen;
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fb->tail = fb->begin;
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}
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else
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{
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/* Scrivi tutto il blocco */
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memcpy(fb->tail, block, len);
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fb->tail += len;
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return;
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}
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}
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for(;;)
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{
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while (!(freelen = fb->head - fb->tail - 1))
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Delay(FIFO_POLLDELAY);
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/* C'e' abbastanza spazio per scrivere tutto il blocco? */
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if (freelen < len)
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{
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/* Scrivi quello che entra fino alla fine del buffer */
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memcpy(fb->tail, block, freelen);
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block += freelen;
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len -= freelen;
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fb->tail += freelen;
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}
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else
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{
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/* Scrivi tutto il blocco */
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memcpy(fb->tail, block, len);
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fb->tail += len;
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return;
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}
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}
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}
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#endif
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/** \} */ /* defgroup fifobuf */
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#endif /* STRUCT_FIFO_H */
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