+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction. Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License. This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2003, 2004 Develer S.r.l. (http://www.develer.com/)
+ * Copyright 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
+ *
+ * -->
+ *
+ * \version $Id: fifobuf.h 1532 2008-08-04 07:21:26Z bernie $
+ *
+ * \author Bernie Innocenti <bernie@codewiz.org>
+ *
+ * \brief General pourpose FIFO buffer implemented with a ring buffer
+ *
+ * \li \c begin points to the first buffer element;
+ * \li \c end points to the last buffer element (unlike the STL convention);
+ * \li \c head points to the element to be extracted next;
+ * \li \c tail points to the location following the last insertion;
+ * \li when any of the pointers advances beyond \c end, it is reset
+ * back to \c begin.
+ *
+ * \code
+ *
+ * +-----------------------------------+
+ * | empty | valid data | empty |
+ * +-----------------------------------+
+ * ^ ^ ^ ^
+ * begin head tail end
+ *
+ * \endcode
+ *
+ * The buffer is EMPTY when \c head and \c tail point to the same location:
+ * \code head == tail \endcode
+ *
+ * The buffer is FULL when \c tail points to the location immediately
+ * after \c head:
+ * \code tail == head - 1 \endcode
+ *
+ * The buffer is also FULL when \c tail points to the last buffer
+ * location and head points to the first one:
+ * \code head == begin && tail == end \endcode
+ */
+
+#ifndef MWARE_FIFO_H
+#define MWARE_FIFO_H
+
+#include <cpu/types.h>
+#include <cpu/irq.h>
+#include <cfg/debug.h>
+
+typedef struct FIFOBuffer
+{
+ unsigned char * volatile head;
+ unsigned char * volatile tail;
+ unsigned char *begin;
+ unsigned char *end;
+} FIFOBuffer;
+
+
+#define ASSERT_VALID_FIFO(fifo) \
+ ATOMIC( \
+ ASSERT((fifo)->head >= (fifo)->begin); \
+ ASSERT((fifo)->head <= (fifo)->end); \
+ ASSERT((fifo)->tail >= (fifo)->begin); \
+ ASSERT((fifo)->tail <= (fifo)->end); \
+ )
+
+
+/**
+ * Check whether the fifo is empty
+ *
+ * \note Calling fifo_isempty() is safe while a concurrent
+ * execution context is calling fifo_push() or fifo_pop()
+ * only if the CPU can atomically update a pointer
+ * (which the AVR and other 8-bit processors can't do).
+ *
+ * \sa fifo_isempty_locked
+ */
+INLINE bool fifo_isempty(const FIFOBuffer *fb)
+{
+ //ASSERT_VALID_FIFO(fb);
+ return fb->head == fb->tail;
+}
+
+
+/**
+ * Check whether the fifo is full
+ *
+ * \note Calling fifo_isfull() is safe while a concurrent
+ * execution context is calling fifo_pop() and the
+ * CPU can update a pointer atomically.
+ * It is NOT safe when the other context calls
+ * fifo_push().
+ * This limitation is not usually problematic in a
+ * consumer/producer scenario because the
+ * fifo_isfull() and fifo_push() are usually called
+ * in the producer context.
+ */
+INLINE bool fifo_isfull(const FIFOBuffer *fb)
+{
+ //ASSERT_VALID_FIFO(fb);
+ return
+ ((fb->head == fb->begin) && (fb->tail == fb->end))
+ || (fb->tail == fb->head - 1);
+}
+
+
+/**
+ * Push a character on the fifo buffer.
+ *
+ * \note Calling \c fifo_push() on a full buffer is undefined.
+ * The caller must make sure the buffer has at least
+ * one free slot before calling this function.
+ *
+ * \note It is safe to call fifo_pop() and fifo_push() from
+ * concurrent contexts, unless the CPU can't update
+ * a pointer atomically (which the AVR and other 8-bit
+ * processors can't do).
+ *
+ * \sa fifo_push_locked
+ */
+INLINE void fifo_push(FIFOBuffer *fb, unsigned char c)
+{
+#ifdef __MWERKS__
+#pragma interrupt called
+#endif
+ //ASSERT_VALID_FIFO(fb);
+
+ /* Write at tail position */
+ *(fb->tail) = c;
+
+ if (UNLIKELY(fb->tail == fb->end))
+ /* wrap tail around */
+ fb->tail = fb->begin;
+ else
+ /* Move tail forward */
+ fb->tail++;
+}
+
+
+/**
+ * Pop a character from the fifo buffer.
+ *
+ * \note Calling \c fifo_pop() on an empty buffer is undefined.
+ * The caller must make sure the buffer contains at least
+ * one character before calling this function.
+ *
+ * \note It is safe to call fifo_pop() and fifo_push() from
+ * concurrent contexts.
+ */
+INLINE unsigned char fifo_pop(FIFOBuffer *fb)
+{
+#ifdef __MWERKS__
+#pragma interrupt called
+#endif
+ //ASSERT_VALID_FIFO(fb);
+
+ if (UNLIKELY(fb->head == fb->end))
+ {
+ /* wrap head around */
+ fb->head = fb->begin;
+ return *(fb->end);
+ }
+ else
+ /* move head forward */
+ return *(fb->head++);
+}
+
+
+/**
+ * Make the fifo empty, discarding all its current contents.
+ */
+INLINE void fifo_flush(FIFOBuffer *fb)
+{
+ //ASSERT_VALID_FIFO(fb);
+ fb->head = fb->tail;
+}
+
+
+#if CPU_REG_BITS >= CPU_BITS_PER_PTR
+
+ /*
+ * 16/32bit CPUs that can update a pointer with a single write
+ * operation, no need to disable interrupts.
+ */
+ #define fifo_isempty_locked(fb) fifo_isempty((fb))
+ #define fifo_push_locked(fb, c) fifo_push((fb), (c))
+ #define fifo_pop_locked(fb) fifo_pop((fb))
+ #define fifo_flush_locked(fb) fifo_flush((fb))
+
+#else /* CPU_REG_BITS < CPU_BITS_PER_PTR */
+
+ /**
+ * Similar to fifo_isempty(), but with stronger guarantees for
+ * concurrent access between user and interrupt code.
+ *
+ * \note This is actually only needed for 8-bit processors.
+ *
+ * \sa fifo_isempty()
+ */
+ INLINE bool fifo_isempty_locked(const FIFOBuffer *fb)
+ {
+ bool result;
+ ATOMIC(result = fifo_isempty(fb));
+ return result;
+ }
+
+
+ /**
+ * Similar to fifo_push(), but with stronger guarantees for
+ * concurrent access between user and interrupt code.
+ *
+ * \note This is actually only needed for 8-bit processors.
+ *
+ * \sa fifo_push()
+ */
+ INLINE void fifo_push_locked(FIFOBuffer *fb, unsigned char c)
+ {
+ ATOMIC(fifo_push(fb, c));
+ }
+
+ /* Probably not really needed, but hard to prove. */
+ INLINE unsigned char fifo_pop_locked(FIFOBuffer *fb)
+ {
+ unsigned char c;
+ ATOMIC(c = fifo_pop(fb));
+ return c;
+ }
+
+ /**
+ * Similar to fifo_flush(), but with stronger guarantees for
+ * concurrent access between user and interrupt code.
+ *
+ * \note This is actually only needed for 8-bit processors.
+ *
+ * \sa fifo_flush()
+ */
+ INLINE void fifo_flush_locked(FIFOBuffer *fb)
+ {
+ ATOMIC(fifo_flush(fb));
+ }
+
+#endif /* CPU_REG_BITS < BITS_PER_PTR */
+
+
+/**
+ * Thread safe version of fifo_isfull()
+ */
+INLINE bool fifo_isfull_locked(const FIFOBuffer *_fb)
+{
+ bool result;
+ ATOMIC(result = fifo_isfull(_fb));
+ return result;
+}
+
+
+/**
+ * FIFO Initialization.
+ */
+INLINE void fifo_init(FIFOBuffer *fb, unsigned char *buf, size_t size)
+{
+ /* FIFO buffers have a known bug with 1-byte buffers. */
+ ASSERT(size > 1);
+
+ fb->head = fb->tail = fb->begin = buf;
+ fb->end = buf + size - 1;
+}
+
+/**
+ * \return Lenght of the FIFOBuffer \a fb.
+ */
+INLINE size_t fifo_len(FIFOBuffer *fb)
+{
+ return fb->end - fb->begin;
+}
+
+
+#if 0
+
+/*
+ * UNTESTED: if uncommented, to be moved in fifobuf.c
+ */
+void fifo_pushblock(FIFOBuffer *fb, unsigned char *block, size_t len)
+{
+ size_t freelen;
+
+ /* Se c'e' spazio da tail alla fine del buffer */
+ if (fb->tail >= fb->head)
+ {
+ freelen = fb->end - fb->tail + 1;
+
+ /* C'e' abbastanza spazio per scrivere tutto il blocco? */
+ if (freelen < len)
+ {
+ /* Scrivi quello che entra fino alla fine del buffer */
+ memcpy(fb->tail, block, freelen);
+ block += freelen;
+ len -= freelen;
+ fb->tail = fb->begin;
+ }
+ else
+ {
+ /* Scrivi tutto il blocco */
+ memcpy(fb->tail, block, len);
+ fb->tail += len;
+ return;
+ }
+ }
+
+ for(;;)
+ {
+ while (!(freelen = fb->head - fb->tail - 1))
+ Delay(FIFO_POLLDELAY);
+
+ /* C'e' abbastanza spazio per scrivere tutto il blocco? */
+ if (freelen < len)
+ {
+ /* Scrivi quello che entra fino alla fine del buffer */
+ memcpy(fb->tail, block, freelen);
+ block += freelen;
+ len -= freelen;
+ fb->tail += freelen;
+ }
+ else
+ {
+ /* Scrivi tutto il blocco */
+ memcpy(fb->tail, block, len);
+ fb->tail += len;
+ return;
+ }
+ }
+}
+#endif
+
+#endif /* MWARE_FIFO_H */
+