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 1.4 2004/06/06 16:11:17 bernie
45 * Protect MetroWerks specific pragmas with #ifdef's
47 * Revision 1.3 2004/06/03 15:04:10 aleph
48 * Merge improvements from project_ks (mainly inlining)
50 * Revision 1.2 2004/06/03 11:27:09 bernie
51 * Add dual-license information.
53 * Revision 1.1 2004/05/23 15:43:16 bernie
54 * Import mware modules.
56 * Revision 1.3 2004/05/22 17:55:58 rasky
57 * \samp non esiste in doxygen
59 * Revision 1.2 2004/04/27 11:13:29 rasky
60 * Spostate tutte le definizioni CPU-specific da compiler.h nel nuovo file cpu.h
62 * Revision 1.1 2004/04/21 17:38:25 rasky
65 * Revision 1.4 2004/03/24 15:37:03 bernie
66 * Remove Copyright messages from Doxygen output
68 * Revision 1.3 2004/03/18 18:11:07 bernie
69 * Add thread-safe FIFO handling macros
71 * Revision 1.2 2004/03/01 08:00:36 bernie
74 * Revision 1.1 2003/12/07 04:04:20 bernie
75 * Initial project_ks framework.
77 * Revision 1.1 2003/11/21 16:36:17 aleph
78 * Rename from fifo to fifobuf to avoid conflict with BSP fifo.h header
80 * Revision 1.1 2003/11/20 22:17:41 aleph
81 * Add fifo buffer used by serial
90 typedef struct FIFOBuffer
92 unsigned char * volatile head;
93 unsigned char * volatile tail;
99 /* Public function prototypes */
100 INLINE bool fifo_isempty(const FIFOBuffer *fb);
101 INLINE bool fifo_isempty_locked(const FIFOBuffer *fb);
102 INLINE bool fifo_isfull(const FIFOBuffer *fb);
103 INLINE bool fifo_isfull_locked(const FIFOBuffer *fb);
105 #pragma interrupt called
107 INLINE void fifo_push(FIFOBuffer *fb, unsigned char c);
109 #pragma interrupt called
111 INLINE unsigned char fifo_pop(FIFOBuffer *fb);
112 INLINE void fifo_flush(FIFOBuffer *fb);
113 INLINE void fifo_init(FIFOBuffer *fb, unsigned char *buf, size_t size);
117 * Check whether the fifo is empty
119 * \note Calling fifo_isempty() is safe while a concurrent
120 * execution context is calling fifo_push() or fifo_pop()
121 * only if the CPU can atomically update a pointer.
123 INLINE bool fifo_isempty(const FIFOBuffer *fb)
125 return fb->head == fb->tail;
130 * Check whether the fifo is full
132 * \note Calling fifo_isfull() is safe while a concurrent
133 * execution context is calling fifo_pop() and the
134 * CPU can update a pointer atomically.
135 * It is NOT safe when the other context calls
137 * This limitation is not usually problematic in a
138 * consumer/producer scenario because the
139 * fifo_isfull() and fifo_push() are usually called
140 * in the producer context.
142 INLINE bool fifo_isfull(const FIFOBuffer *fb)
145 ((fb->head == fb->begin) && (fb->tail == fb->end))
146 || (fb->tail == fb->head - 1);
150 #if !defined(__AVR__)
152 /* No tricks needed on 16/32bit CPUs */
153 # define fifo_isempty_locked(fb) fifo_isempty((fb))
157 INLINE bool fifo_isempty_locked(const FIFOBuffer *fb)
162 DISABLE_IRQSAVE(flags);
163 result = fifo_isempty(fb);
164 ENABLE_IRQRESTORE(flags);
169 #endif /* !__AVR__ */
173 * Thread safe version of fifo_isfull()
175 INLINE bool fifo_isfull_locked(const FIFOBuffer *_fb)
180 DISABLE_IRQSAVE(_flags);
181 _result = fifo_isfull(_fb);
182 ENABLE_IRQRESTORE(_flags);
189 * Pop a character from the fifo buffer.
191 * \note Calling \c fifo_push() on a full buffer is undefined.
192 * The caller must make sure the buffer has at least
193 * one free slot before calling this function.
195 * \note It is safe to call fifo_pop() and fifo_push() from
196 * concurrent contexts.
198 INLINE void fifo_push(FIFOBuffer *fb, unsigned char c)
200 /* Write at tail position */
203 if (fb->tail == fb->end)
204 /* wrap tail around */
205 fb->tail = fb->begin;
207 /* Move tail forward */
213 * Pop a character from the fifo buffer.
215 * \note Calling \c fifo_pop() on an empty buffer is undefined.
216 * The caller must make sure the buffer contains at least
217 * one character before calling this function.
219 * \note It is safe to call fifo_pop() and fifo_push() from
220 * concurrent contexts.
222 INLINE unsigned char fifo_pop(FIFOBuffer *fb)
224 if (fb->head == fb->end)
226 /* wrap head around */
227 fb->head = fb->begin;
231 /* move head forward */
232 return *(fb->head++);
237 * Make the fifo empty, discarding all its current contents.
239 INLINE void fifo_flush(FIFOBuffer *fb)
246 * FIFO Initialization.
248 INLINE void fifo_init(FIFOBuffer *fb, unsigned char *buf, size_t size)
250 fb->head = fb->tail = fb->begin = buf;
251 fb->end = buf + size - 1;
259 * UNTESTED: if uncommented, to be moved in fifobuf.c
261 void fifo_pushblock(FIFOBuffer *fb, unsigned char *block, size_t len)
265 /* Se c'e' spazio da tail alla fine del buffer */
266 if (fb->tail >= fb->head)
268 freelen = fb->end - fb->tail + 1;
270 /* C'e' abbastanza spazio per scrivere tutto il blocco? */
273 /* Scrivi quello che entra fino alla fine del buffer */
274 memcpy(fb->tail, block, freelen);
277 fb->tail = fb->begin;
281 /* Scrivi tutto il blocco */
282 memcpy(fb->tail, block, len);
290 while (!(freelen = fb->head - fb->tail - 1))
291 Delay(FIFO_POLLDELAY);
293 /* C'e' abbastanza spazio per scrivere tutto il blocco? */
296 /* Scrivi quello che entra fino alla fine del buffer */
297 memcpy(fb->tail, block, freelen);
304 /* Scrivi tutto il blocco */
305 memcpy(fb->tail, block, len);
313 #endif /* MWARE_FIFO_H */