4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
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11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
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18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2003, 2004 Develer S.r.l. (http://www.develer.com/)
30 * Copyright 2001 Bernardo Innocenti <bernie@develer.com>
36 * \author Bernardo Innocenti <bernie@develer.com>
38 * \brief General pourpose FIFO buffer implemented with a ring buffer
40 * \li \c begin points to the first buffer element;
41 * \li \c end points to the last buffer element (unlike the STL convention);
42 * \li \c head points to the element to be extracted next;
43 * \li \c tail points to the location following the last insertion;
44 * \li when any of the pointers advances beyond \c end, it is reset
49 * +-----------------------------------+
50 * | empty | valid data | empty |
51 * +-----------------------------------+
57 * The buffer is EMPTY when \c head and \c tail point to the same location:
58 * \code head == tail \endcode
60 * The buffer is FULL when \c tail points to the location immediately
62 * \code tail == head - 1 \endcode
64 * The buffer is also FULL when \c tail points to the last buffer
65 * location and head points to the first one:
66 * \code head == begin && tail == end \endcode
72 #include <cpu/types.h>
74 #include <cfg/debug.h>
76 typedef struct FIFOBuffer
78 unsigned char * volatile head;
79 unsigned char * volatile tail;
85 #define ASSERT_VALID_FIFO(fifo) \
87 ASSERT((fifo)->head >= (fifo)->begin); \
88 ASSERT((fifo)->head <= (fifo)->end); \
89 ASSERT((fifo)->tail >= (fifo)->begin); \
90 ASSERT((fifo)->tail <= (fifo)->end); \
95 * Check whether the fifo is empty
97 * \note Calling fifo_isempty() is safe while a concurrent
98 * execution context is calling fifo_push() or fifo_pop()
99 * only if the CPU can atomically update a pointer
100 * (which the AVR and other 8-bit processors can't do).
102 * \sa fifo_isempty_locked
104 INLINE bool fifo_isempty(const FIFOBuffer *fb)
106 //ASSERT_VALID_FIFO(fb);
107 return fb->head == fb->tail;
112 * Check whether the fifo is full
114 * \note Calling fifo_isfull() is safe while a concurrent
115 * execution context is calling fifo_pop() and the
116 * CPU can update a pointer atomically.
117 * It is NOT safe when the other context calls
119 * This limitation is not usually problematic in a
120 * consumer/producer scenario because the
121 * fifo_isfull() and fifo_push() are usually called
122 * in the producer context.
124 INLINE bool fifo_isfull(const FIFOBuffer *fb)
126 //ASSERT_VALID_FIFO(fb);
128 ((fb->head == fb->begin) && (fb->tail == fb->end))
129 || (fb->tail == fb->head - 1);
134 * Push a character on the fifo buffer.
136 * \note Calling \c fifo_push() on a full buffer is undefined.
137 * The caller must make sure the buffer has at least
138 * one free slot before calling this function.
140 * \note It is safe to call fifo_pop() and fifo_push() from
141 * concurrent contexts, unless the CPU can't update
142 * a pointer atomically (which the AVR and other 8-bit
143 * processors can't do).
145 * \sa fifo_push_locked
147 INLINE void fifo_push(FIFOBuffer *fb, unsigned char c)
150 #pragma interrupt called
152 //ASSERT_VALID_FIFO(fb);
154 /* Write at tail position */
157 if (UNLIKELY(fb->tail == fb->end))
158 /* wrap tail around */
159 fb->tail = fb->begin;
161 /* Move tail forward */
167 * Pop a character from the fifo buffer.
169 * \note Calling \c fifo_pop() on an empty buffer is undefined.
170 * The caller must make sure the buffer contains at least
171 * one character before calling this function.
173 * \note It is safe to call fifo_pop() and fifo_push() from
174 * concurrent contexts.
176 INLINE unsigned char fifo_pop(FIFOBuffer *fb)
179 #pragma interrupt called
181 //ASSERT_VALID_FIFO(fb);
183 if (UNLIKELY(fb->head == fb->end))
185 /* wrap head around */
186 fb->head = fb->begin;
190 /* move head forward */
191 return *(fb->head++);
196 * Make the fifo empty, discarding all its current contents.
198 INLINE void fifo_flush(FIFOBuffer *fb)
200 //ASSERT_VALID_FIFO(fb);
205 #if CPU_REG_BITS >= CPU_BITS_PER_PTR
208 * 16/32bit CPUs that can update a pointer with a single write
209 * operation, no need to disable interrupts.
211 #define fifo_isempty_locked(fb) fifo_isempty((fb))
212 #define fifo_push_locked(fb, c) fifo_push((fb), (c))
213 #define fifo_pop_locked(fb) fifo_pop((fb))
214 #define fifo_flush_locked(fb) fifo_flush((fb))
216 #else /* CPU_REG_BITS < CPU_BITS_PER_PTR */
219 * Similar to fifo_isempty(), but with stronger guarantees for
220 * concurrent access between user and interrupt code.
222 * \note This is actually only needed for 8-bit processors.
226 INLINE bool fifo_isempty_locked(const FIFOBuffer *fb)
229 ATOMIC(result = fifo_isempty(fb));
235 * Similar to fifo_push(), but with stronger guarantees for
236 * concurrent access between user and interrupt code.
238 * \note This is actually only needed for 8-bit processors.
242 INLINE void fifo_push_locked(FIFOBuffer *fb, unsigned char c)
244 ATOMIC(fifo_push(fb, c));
247 /* Probably not really needed, but hard to prove. */
248 INLINE unsigned char fifo_pop_locked(FIFOBuffer *fb)
251 ATOMIC(c = fifo_pop(fb));
256 * Similar to fifo_flush(), but with stronger guarantees for
257 * concurrent access between user and interrupt code.
259 * \note This is actually only needed for 8-bit processors.
263 INLINE void fifo_flush_locked(FIFOBuffer *fb)
265 ATOMIC(fifo_flush(fb));
268 #endif /* CPU_REG_BITS < BITS_PER_PTR */
272 * Thread safe version of fifo_isfull()
274 INLINE bool fifo_isfull_locked(const FIFOBuffer *_fb)
277 ATOMIC(result = fifo_isfull(_fb));
283 * FIFO Initialization.
285 INLINE void fifo_init(FIFOBuffer *fb, unsigned char *buf, size_t size)
287 /* FIFO buffers have a known bug with 1-byte buffers. */
290 fb->head = fb->tail = fb->begin = buf;
291 fb->end = buf + size - 1;
295 * \return Lenght of the FIFOBuffer \a fb.
297 INLINE size_t fifo_len(FIFOBuffer *fb)
299 return fb->end - fb->begin;
306 * UNTESTED: if uncommented, to be moved in fifobuf.c
308 void fifo_pushblock(FIFOBuffer *fb, unsigned char *block, size_t len)
312 /* Se c'e' spazio da tail alla fine del buffer */
313 if (fb->tail >= fb->head)
315 freelen = fb->end - fb->tail + 1;
317 /* C'e' abbastanza spazio per scrivere tutto il blocco? */
320 /* Scrivi quello che entra fino alla fine del buffer */
321 memcpy(fb->tail, block, freelen);
324 fb->tail = fb->begin;
328 /* Scrivi tutto il blocco */
329 memcpy(fb->tail, block, len);
337 while (!(freelen = fb->head - fb->tail - 1))
338 Delay(FIFO_POLLDELAY);
340 /* C'e' abbastanza spazio per scrivere tutto il blocco? */
343 /* Scrivi quello che entra fino alla fine del buffer */
344 memcpy(fb->tail, block, freelen);
351 /* Scrivi tutto il blocco */
352 memcpy(fb->tail, block, len);
360 #endif /* MWARE_FIFO_H */