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 1.3 2004/06/03 15:04:10 aleph
45 * Merge improvements from project_ks (mainly inlining)
47 * Revision 1.2 2004/06/03 11:27:09 bernie
48 * Add dual-license information.
50 * Revision 1.1 2004/05/23 15:43:16 bernie
51 * Import mware modules.
53 * Revision 1.3 2004/05/22 17:55:58 rasky
54 * \samp non esiste in doxygen
56 * Revision 1.2 2004/04/27 11:13:29 rasky
57 * Spostate tutte le definizioni CPU-specific da compiler.h nel nuovo file cpu.h
59 * Revision 1.1 2004/04/21 17:38:25 rasky
62 * Revision 1.4 2004/03/24 15:37:03 bernie
63 * Remove Copyright messages from Doxygen output
65 * Revision 1.3 2004/03/18 18:11:07 bernie
66 * Add thread-safe FIFO handling macros
68 * Revision 1.2 2004/03/01 08:00:36 bernie
71 * Revision 1.1 2003/12/07 04:04:20 bernie
72 * Initial project_ks framework.
74 * Revision 1.1 2003/11/21 16:36:17 aleph
75 * Rename from fifo to fifobuf to avoid conflict with BSP fifo.h header
77 * Revision 1.1 2003/11/20 22:17:41 aleph
78 * Add fifo buffer used by serial
87 typedef struct FIFOBuffer
89 unsigned char * volatile head;
90 unsigned char * volatile tail;
96 /* Public function prototypes */
97 INLINE bool fifo_isempty(const FIFOBuffer *fb);
98 INLINE bool fifo_isempty_locked(const FIFOBuffer *fb);
99 INLINE bool fifo_isfull(const FIFOBuffer *fb);
100 INLINE bool fifo_isfull_locked(const FIFOBuffer *fb);
101 #pragma interrupt called
102 INLINE void fifo_push(FIFOBuffer *fb, unsigned char c);
103 #pragma interrupt called
104 INLINE unsigned char fifo_pop(FIFOBuffer *fb);
105 INLINE void fifo_flush(FIFOBuffer *fb);
106 INLINE void fifo_init(FIFOBuffer *fb, unsigned char *buf, size_t size);
110 * Check whether the fifo is empty
112 * \note Calling fifo_isempty() is safe while a concurrent
113 * execution context is calling fifo_push() or fifo_pop()
114 * only if the CPU can atomically update a pointer.
116 INLINE bool fifo_isempty(const FIFOBuffer *fb)
118 return fb->head == fb->tail;
123 * Check whether the fifo is full
125 * \note Calling fifo_isfull() is safe while a concurrent
126 * execution context is calling fifo_pop() and the
127 * CPU can update a pointer atomically.
128 * It is NOT safe when the other context calls
130 * This limitation is not usually problematic in a
131 * consumer/producer scenario because the
132 * fifo_isfull() and fifo_push() are usually called
133 * in the producer context.
135 INLINE bool fifo_isfull(const FIFOBuffer *fb)
138 ((fb->head == fb->begin) && (fb->tail == fb->end))
139 || (fb->tail == fb->head - 1);
143 #if !defined(__AVR__)
145 /* No tricks needed on 16/32bit CPUs */
146 # define fifo_isempty_locked(fb) fifo_isempty((fb))
150 INLINE bool fifo_isempty_locked(const FIFOBuffer *fb)
155 DISABLE_IRQSAVE(flags);
156 result = fifo_isempty(fb);
157 ENABLE_IRQRESTORE(flags);
162 #endif /* !__AVR__ */
166 * Thread safe version of fifo_isfull()
168 INLINE bool fifo_isfull_locked(const FIFOBuffer *_fb)
173 DISABLE_IRQSAVE(_flags);
174 _result = fifo_isfull(_fb);
175 ENABLE_IRQRESTORE(_flags);
182 * Pop a character from the fifo buffer.
184 * \note Calling \c fifo_push() on a full buffer is undefined.
185 * The caller must make sure the buffer has at least
186 * one free slot before calling this function.
188 * \note It is safe to call fifo_pop() and fifo_push() from
189 * concurrent contexts.
191 INLINE void fifo_push(FIFOBuffer *fb, unsigned char c)
193 /* Write at tail position */
196 if (fb->tail == fb->end)
197 /* wrap tail around */
198 fb->tail = fb->begin;
200 /* Move tail forward */
206 * Pop a character from the fifo buffer.
208 * \note Calling \c fifo_pop() on an empty buffer is undefined.
209 * The caller must make sure the buffer contains at least
210 * one character before calling this function.
212 * \note It is safe to call fifo_pop() and fifo_push() from
213 * concurrent contexts.
215 INLINE unsigned char fifo_pop(FIFOBuffer *fb)
217 if (fb->head == fb->end)
219 /* wrap head around */
220 fb->head = fb->begin;
224 /* move head forward */
225 return *(fb->head++);
230 * Make the fifo empty, discarding all its current contents.
232 INLINE void fifo_flush(FIFOBuffer *fb)
239 * FIFO Initialization.
241 INLINE void fifo_init(FIFOBuffer *fb, unsigned char *buf, size_t size)
243 fb->head = fb->tail = fb->begin = buf;
244 fb->end = buf + size - 1;
252 * UNTESTED: if uncommented, to be moved in fifobuf.c
254 void fifo_pushblock(FIFOBuffer *fb, unsigned char *block, size_t len)
258 /* Se c'e' spazio da tail alla fine del buffer */
259 if (fb->tail >= fb->head)
261 freelen = fb->end - fb->tail + 1;
263 /* C'e' abbastanza spazio per scrivere tutto il blocco? */
266 /* Scrivi quello che entra fino alla fine del buffer */
267 memcpy(fb->tail, block, freelen);
270 fb->tail = fb->begin;
274 /* Scrivi tutto il blocco */
275 memcpy(fb->tail, block, len);
283 while (!(freelen = fb->head - fb->tail - 1))
284 Delay(FIFO_POLLDELAY);
286 /* C'e' abbastanza spazio per scrivere tutto il blocco? */
289 /* Scrivi quello che entra fino alla fine del buffer */
290 memcpy(fb->tail, block, freelen);
297 /* Scrivi tutto il blocco */
298 memcpy(fb->tail, block, len);
306 #endif /* MWARE_FIFO_H */