4 * Copyright 2003,2004 Develer S.r.l. (http://www.develer.com/)
5 * Copyright 2001 Bernardo Innocenti <bernie@develer.com>
6 * This file is part of DevLib - See devlib/README for information.
11 * \author Bernardo Innocenti <bernie@develer.com>
13 * \brief General pourpose FIFO buffer implemented with a ring buffer
15 * \li \c begin punta al primo elemento del buffer,
16 * \li \c end punta all'ultimo elemento,
17 * \li \c head punta al prossimo elemento che verra' estratto,
18 * \li \c tail punta alla posizione successiva all'ultimo elemento inserito.
19 * \li quando uno dei due puntatori raggiunge @c end, viene resettato a @c begin.
23 * +-----------------------------------+
24 * | vuoto | dati validi | vuoto |
25 * +-----------------------------------+
31 * Il buffer e' VUOTO quando head e tail coincidono:
32 * \code head == tail \endcode
34 * Il buffer e' PIENO quando tail si trova immediatamente dietro a head:
35 * \code tail == head - 1 \endcode
37 * Il buffer e' PIENO anche quando tail e' posizionato
38 * sull'ultima posizione del buffer e head sulla prima:
39 * \code head == begin && tail == end \endcode
44 * Revision 1.5 2004/06/06 16:50:35 bernie
45 * Import fixes for race conditions from project_ks.
47 * Revision 1.4 2004/06/06 16:11:17 bernie
48 * Protect MetroWerks specific pragmas with #ifdef's
50 * Revision 1.3 2004/06/03 15:04:10 aleph
51 * Merge improvements from project_ks (mainly inlining)
53 * Revision 1.2 2004/06/03 11:27:09 bernie
54 * Add dual-license information.
56 * Revision 1.1 2004/05/23 15:43:16 bernie
57 * Import mware modules.
59 * Revision 1.3 2004/05/22 17:55:58 rasky
60 * \samp non esiste in doxygen
62 * Revision 1.2 2004/04/27 11:13:29 rasky
63 * Spostate tutte le definizioni CPU-specific da compiler.h nel nuovo file cpu.h
65 * Revision 1.1 2004/04/21 17:38:25 rasky
68 * Revision 1.4 2004/03/24 15:37:03 bernie
69 * Remove Copyright messages from Doxygen output
71 * Revision 1.3 2004/03/18 18:11:07 bernie
72 * Add thread-safe FIFO handling macros
74 * Revision 1.2 2004/03/01 08:00:36 bernie
77 * Revision 1.1 2003/12/07 04:04:20 bernie
78 * Initial project_ks framework.
80 * Revision 1.1 2003/11/21 16:36:17 aleph
81 * Rename from fifo to fifobuf to avoid conflict with BSP fifo.h header
83 * Revision 1.1 2003/11/20 22:17:41 aleph
84 * Add fifo buffer used by serial
93 typedef struct FIFOBuffer
95 unsigned char * volatile head;
96 unsigned char * volatile tail;
102 /* Public function prototypes */
103 INLINE bool fifo_isempty(const FIFOBuffer *fb);
104 INLINE bool fifo_isempty_locked(const FIFOBuffer *fb);
105 INLINE bool fifo_isfull(const FIFOBuffer *fb);
106 INLINE bool fifo_isfull_locked(const FIFOBuffer *fb);
108 #pragma interrupt called
110 INLINE void fifo_push(FIFOBuffer *fb, unsigned char c);
112 #pragma interrupt called
114 INLINE unsigned char fifo_pop(FIFOBuffer *fb);
115 INLINE void fifo_flush(FIFOBuffer *fb);
116 INLINE void fifo_init(FIFOBuffer *fb, unsigned char *buf, size_t size);
120 * Check whether the fifo is empty
122 * \note Calling fifo_isempty() is safe while a concurrent
123 * execution context is calling fifo_push() or fifo_pop()
124 * only if the CPU can atomically update a pointer
125 * (which the AVR and other 8-bit processors can't do).
127 * \sa fifo_isempty_locked
129 INLINE bool fifo_isempty(const FIFOBuffer *fb)
131 return fb->head == fb->tail;
136 * Check whether the fifo is full
138 * \note Calling fifo_isfull() is safe while a concurrent
139 * execution context is calling fifo_pop() and the
140 * CPU can update a pointer atomically.
141 * It is NOT safe when the other context calls
143 * This limitation is not usually problematic in a
144 * consumer/producer scenario because the
145 * fifo_isfull() and fifo_push() are usually called
146 * in the producer context.
148 INLINE bool fifo_isfull(const FIFOBuffer *fb)
151 ((fb->head == fb->begin) && (fb->tail == fb->end))
152 || (fb->tail == fb->head - 1);
157 * Pop a character from the fifo buffer.
159 * \note Calling \c fifo_push() on a full buffer is undefined.
160 * The caller must make sure the buffer has at least
161 * one free slot before calling this function.
163 * \note It is safe to call fifo_pop() and fifo_push() from
164 * concurrent contexts, unless the CPU can't update
165 * a pointer atomically (which the AVR and other 8-bit
166 * processors can't do).
168 * \sa fifo_push_locked
170 INLINE void fifo_push(FIFOBuffer *fb, unsigned char c)
172 /* Write at tail position */
175 if (fb->tail == fb->end)
176 /* wrap tail around */
177 fb->tail = fb->begin;
179 /* Move tail forward */
185 * Pop a character from the fifo buffer.
187 * \note Calling \c fifo_pop() on an empty buffer is undefined.
188 * The caller must make sure the buffer contains at least
189 * one character before calling this function.
191 * \note It is safe to call fifo_pop() and fifo_push() from
192 * concurrent contexts.
194 INLINE unsigned char fifo_pop(FIFOBuffer *fb)
196 if (fb->head == fb->end)
198 /* wrap head around */
199 fb->head = fb->begin;
203 /* move head forward */
204 return *(fb->head++);
209 * Make the fifo empty, discarding all its current contents.
211 INLINE void fifo_flush(FIFOBuffer *fb)
217 #if !defined(__AVR__)
219 /* No tricks needed on 16/32bit CPUs */
220 # define fifo_isempty_locked(fb) fifo_isempty((fb))
221 # define fifo_push_locked(fb, c) fifo_push((fb), (c))
226 * Similar to fifo_isempty(), but with stronger guarantees for
227 * concurrent access between user and interrupt code.
228 * This is actually only needed for 8-bit processors.
232 INLINE bool fifo_isempty_locked(const FIFOBuffer *fb);
233 INLINE bool fifo_isempty_locked(const FIFOBuffer *fb)
238 DISABLE_IRQSAVE(flags);
239 result = fifo_isempty(fb);
240 ENABLE_IRQRESTORE(flags);
246 * Similar to fifo_push(), but with stronger guarantees for
247 * concurrent access between user and interrupt code.
248 * This is actually only needed for 8-bit processors.
252 INLINE void fifo_push_locked(FIFOBuffer *fb, unsigned char c);
253 INLINE void fifo_push_locked(FIFOBuffer *fb, unsigned char c)
256 DISABLE_IRQSAVE(flags);
258 ENABLE_IRQRESTORE(flags);
261 #endif /* !__AVR__ */
265 * Thread safe version of fifo_isfull()
267 INLINE bool fifo_isfull_locked(const FIFOBuffer *_fb)
272 DISABLE_IRQSAVE(_flags);
273 _result = fifo_isfull(_fb);
274 ENABLE_IRQRESTORE(_flags);
282 * FIFO Initialization.
284 INLINE void fifo_init(FIFOBuffer *fb, unsigned char *buf, size_t size)
286 fb->head = fb->tail = fb->begin = buf;
287 fb->end = buf + size - 1;
295 * UNTESTED: if uncommented, to be moved in fifobuf.c
297 void fifo_pushblock(FIFOBuffer *fb, unsigned char *block, size_t len)
301 /* Se c'e' spazio da tail alla fine del buffer */
302 if (fb->tail >= fb->head)
304 freelen = fb->end - fb->tail + 1;
306 /* C'e' abbastanza spazio per scrivere tutto il blocco? */
309 /* Scrivi quello che entra fino alla fine del buffer */
310 memcpy(fb->tail, block, freelen);
313 fb->tail = fb->begin;
317 /* Scrivi tutto il blocco */
318 memcpy(fb->tail, block, len);
326 while (!(freelen = fb->head - fb->tail - 1))
327 Delay(FIFO_POLLDELAY);
329 /* C'e' abbastanza spazio per scrivere tutto il blocco? */
332 /* Scrivi quello che entra fino alla fine del buffer */
333 memcpy(fb->tail, block, freelen);
340 /* Scrivi tutto il blocco */
341 memcpy(fb->tail, block, len);
349 #endif /* MWARE_FIFO_H */