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 1.6 2004/06/06 17:18:04 bernie
45 * Remove redundant declaration of fifo_isempty_locked().
47 * Revision 1.5 2004/06/06 16:50:35 bernie
48 * Import fixes for race conditions from project_ks.
50 * Revision 1.4 2004/06/06 16:11:17 bernie
51 * Protect MetroWerks specific pragmas with #ifdef's
53 * Revision 1.3 2004/06/03 15:04:10 aleph
54 * Merge improvements from project_ks (mainly inlining)
56 * Revision 1.2 2004/06/03 11:27:09 bernie
57 * Add dual-license information.
59 * Revision 1.1 2004/05/23 15:43:16 bernie
60 * Import mware modules.
62 * Revision 1.3 2004/05/22 17:55:58 rasky
63 * \samp non esiste in doxygen
65 * Revision 1.2 2004/04/27 11:13:29 rasky
66 * Spostate tutte le definizioni CPU-specific da compiler.h nel nuovo file cpu.h
68 * Revision 1.1 2004/04/21 17:38:25 rasky
71 * Revision 1.4 2004/03/24 15:37:03 bernie
72 * Remove Copyright messages from Doxygen output
74 * Revision 1.3 2004/03/18 18:11:07 bernie
75 * Add thread-safe FIFO handling macros
77 * Revision 1.2 2004/03/01 08:00:36 bernie
80 * Revision 1.1 2003/12/07 04:04:20 bernie
81 * Initial project_ks framework.
83 * Revision 1.1 2003/11/21 16:36:17 aleph
84 * Rename from fifo to fifobuf to avoid conflict with BSP fifo.h header
86 * Revision 1.1 2003/11/20 22:17:41 aleph
87 * Add fifo buffer used by serial
96 typedef struct FIFOBuffer
98 unsigned char * volatile head;
99 unsigned char * volatile tail;
100 unsigned char *begin;
105 /* Public function prototypes */
106 INLINE bool fifo_isempty(const FIFOBuffer *fb);
107 INLINE bool fifo_isfull(const FIFOBuffer *fb);
108 INLINE bool fifo_isfull_locked(const FIFOBuffer *fb);
110 #pragma interrupt called
112 INLINE void fifo_push(FIFOBuffer *fb, unsigned char c);
114 #pragma interrupt called
116 INLINE unsigned char fifo_pop(FIFOBuffer *fb);
117 INLINE void fifo_flush(FIFOBuffer *fb);
118 INLINE void fifo_init(FIFOBuffer *fb, unsigned char *buf, size_t size);
122 * Check whether the fifo is empty
124 * \note Calling fifo_isempty() is safe while a concurrent
125 * execution context is calling fifo_push() or fifo_pop()
126 * only if the CPU can atomically update a pointer
127 * (which the AVR and other 8-bit processors can't do).
129 * \sa fifo_isempty_locked
131 INLINE bool fifo_isempty(const FIFOBuffer *fb)
133 return fb->head == fb->tail;
138 * Check whether the fifo is full
140 * \note Calling fifo_isfull() is safe while a concurrent
141 * execution context is calling fifo_pop() and the
142 * CPU can update a pointer atomically.
143 * It is NOT safe when the other context calls
145 * This limitation is not usually problematic in a
146 * consumer/producer scenario because the
147 * fifo_isfull() and fifo_push() are usually called
148 * in the producer context.
150 INLINE bool fifo_isfull(const FIFOBuffer *fb)
153 ((fb->head == fb->begin) && (fb->tail == fb->end))
154 || (fb->tail == fb->head - 1);
159 * Pop a character from the fifo buffer.
161 * \note Calling \c fifo_push() on a full buffer is undefined.
162 * The caller must make sure the buffer has at least
163 * one free slot before calling this function.
165 * \note It is safe to call fifo_pop() and fifo_push() from
166 * concurrent contexts, unless the CPU can't update
167 * a pointer atomically (which the AVR and other 8-bit
168 * processors can't do).
170 * \sa fifo_push_locked
172 INLINE void fifo_push(FIFOBuffer *fb, unsigned char c)
174 /* Write at tail position */
177 if (fb->tail == fb->end)
178 /* wrap tail around */
179 fb->tail = fb->begin;
181 /* Move tail forward */
187 * Pop a character from the fifo buffer.
189 * \note Calling \c fifo_pop() on an empty buffer is undefined.
190 * The caller must make sure the buffer contains at least
191 * one character before calling this function.
193 * \note It is safe to call fifo_pop() and fifo_push() from
194 * concurrent contexts.
196 INLINE unsigned char fifo_pop(FIFOBuffer *fb)
198 if (fb->head == fb->end)
200 /* wrap head around */
201 fb->head = fb->begin;
205 /* move head forward */
206 return *(fb->head++);
211 * Make the fifo empty, discarding all its current contents.
213 INLINE void fifo_flush(FIFOBuffer *fb)
219 #if !defined(__AVR__)
221 /* No tricks needed on 16/32bit CPUs */
222 # define fifo_isempty_locked(fb) fifo_isempty((fb))
223 # define fifo_push_locked(fb, c) fifo_push((fb), (c))
228 * Similar to fifo_isempty(), but with stronger guarantees for
229 * concurrent access between user and interrupt code.
230 * This is actually only needed for 8-bit processors.
234 INLINE bool fifo_isempty_locked(const FIFOBuffer *fb);
235 INLINE bool fifo_isempty_locked(const FIFOBuffer *fb)
240 DISABLE_IRQSAVE(flags);
241 result = fifo_isempty(fb);
242 ENABLE_IRQRESTORE(flags);
248 * Similar to fifo_push(), but with stronger guarantees for
249 * concurrent access between user and interrupt code.
250 * This is actually only needed for 8-bit processors.
254 INLINE void fifo_push_locked(FIFOBuffer *fb, unsigned char c);
255 INLINE void fifo_push_locked(FIFOBuffer *fb, unsigned char c)
258 DISABLE_IRQSAVE(flags);
260 ENABLE_IRQRESTORE(flags);
263 #endif /* !__AVR__ */
267 * Thread safe version of fifo_isfull()
269 INLINE bool fifo_isfull_locked(const FIFOBuffer *_fb)
274 DISABLE_IRQSAVE(_flags);
275 _result = fifo_isfull(_fb);
276 ENABLE_IRQRESTORE(_flags);
284 * FIFO Initialization.
286 INLINE void fifo_init(FIFOBuffer *fb, unsigned char *buf, size_t size)
288 fb->head = fb->tail = fb->begin = buf;
289 fb->end = buf + size - 1;
297 * UNTESTED: if uncommented, to be moved in fifobuf.c
299 void fifo_pushblock(FIFOBuffer *fb, unsigned char *block, size_t len)
303 /* Se c'e' spazio da tail alla fine del buffer */
304 if (fb->tail >= fb->head)
306 freelen = fb->end - fb->tail + 1;
308 /* C'e' abbastanza spazio per scrivere tutto il blocco? */
311 /* Scrivi quello che entra fino alla fine del buffer */
312 memcpy(fb->tail, block, freelen);
315 fb->tail = fb->begin;
319 /* Scrivi tutto il blocco */
320 memcpy(fb->tail, block, len);
328 while (!(freelen = fb->head - fb->tail - 1))
329 Delay(FIFO_POLLDELAY);
331 /* C'e' abbastanza spazio per scrivere tutto il blocco? */
334 /* Scrivi quello che entra fino alla fine del buffer */
335 memcpy(fb->tail, block, freelen);
342 /* Scrivi tutto il blocco */
343 memcpy(fb->tail, block, len);
351 #endif /* MWARE_FIFO_H */