4 Copyright 2008, 2012 Michel Pollet <buserror@gmail.com>
6 This file is part of simavr.
8 simavr is free software: you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation, either version 3 of the License, or
11 (at your option) any later version.
13 simavr is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with simavr. If not, see <http://www.gnu.org/licenses/>.
22 /* Licensed to Vidiactive by Michel Pollet under the terms of the VECL */
25 * FIFO helpers, aka circular buffers
27 * these macros define accessories for FIFOs of any name, type and
28 * any (power of two) size
31 #ifndef __FIFO_DECLARE__
32 #define __FIFO_DECLARE__
36 DECLARE_FIFO(uint8_t, myfifo, 128);
39 enum : myfifo_overflow_f
42 // write a byte into the fifo, return 1 if there was room, 0 if there wasn't
43 int myfifo_write(myfifo_t *c, uint8_t b);
44 // reads a byte from the fifo, return 0 if empty. Use myfifo_isempty() to check beforehand
45 uint8_t myfifo_read(myfifo_t *c);
46 int myfifo_isfull(myfifo_t *c);
47 int myfifo_isempty(myfifo_t *c);
48 // returns number of items to read now
49 uint16_t myfifo_get_read_size(myfifo_t *c);
50 // read item at offset o from read cursor, no cursor advance
51 uint8_t myfifo_read_at(myfifo_t *c, uint16_t o);
52 // write b at offset o compared to current write cursor, no cursor advance
53 void myfifo_write_at(myfifo_t *c, uint16_t o, uint8_t b);
55 In your .c you need to 'implement' the fifo:
56 DEFINE_FIFO(uint8_t, myfifo)
58 To use the fifo, you must declare at least one :
59 myfifo_t fifo = FIFO_NULL;
61 while (!myfifo_isfull(&fifo))
62 myfifo_write(&fifo, 0xaa);
64 while (!myfifo_isempty(&fifo))
65 b = myfifo_read(&fifo);
71 #define FIFO_CURSOR_TYPE uint8_t
72 #define FIFO_BOOL_TYPE char
75 #ifndef FIFO_CURSOR_TYPE
76 #define FIFO_CURSOR_TYPE uint16_t
78 #ifndef FIFO_BOOL_TYPE
79 #define FIFO_BOOL_TYPE int
82 #define FIFO_INLINE inline
85 #ifndef FIFO_ZERO_INIT
86 #define FIFO_ZERO_INIT {0}
88 #define FIFO_NULL { FIFO_ZERO_INIT, 0, 0, 0 }
90 #define DECLARE_FIFO(__type, __name, __size) \
91 enum { __name##_overflow_f = (1 << 0) }; \
92 enum { __name##_fifo_size = (__size) }; \
93 typedef struct __name##_t { \
94 __type buffer[__name##_fifo_size]; \
95 volatile FIFO_CURSOR_TYPE read; \
96 volatile FIFO_CURSOR_TYPE write; \
97 volatile uint8_t flags; \
100 #define DEFINE_FIFO(__type, __name) \
101 static FIFO_INLINE FIFO_BOOL_TYPE __name##_write(__name##_t * c, __type b)\
103 FIFO_CURSOR_TYPE now = c->write;\
104 FIFO_CURSOR_TYPE next = (now + 1) & (__name##_fifo_size-1);\
105 if (c->read != next) { \
112 static FIFO_INLINE FIFO_BOOL_TYPE __name##_isfull(__name##_t *c)\
114 FIFO_CURSOR_TYPE next = (c->write + 1) & (__name##_fifo_size-1);\
115 return c->read == next;\
117 static FIFO_INLINE FIFO_BOOL_TYPE __name##_isempty(__name##_t * c)\
119 return c->read == c->write;\
121 static FIFO_INLINE __type __name##_read(__name##_t * c)\
123 __type res = FIFO_ZERO_INIT; \
124 if (c->read == c->write)\
126 FIFO_CURSOR_TYPE read = c->read;\
127 res = c->buffer[read];\
128 c->read = (read + 1) & (__name##_fifo_size-1);\
131 static FIFO_INLINE FIFO_CURSOR_TYPE __name##_get_read_size(__name##_t *c)\
133 return c->write > c->read ? c->write - c->read : __name##_fifo_size - 1 - c->read + c->write;\
135 static FIFO_INLINE void __name##_read_offset(__name##_t *c, FIFO_CURSOR_TYPE o)\
137 c->read = (c->read + o) & (__name##_fifo_size-1);\
139 static FIFO_INLINE __type __name##_read_at(__name##_t *c, FIFO_CURSOR_TYPE o)\
141 return c->buffer[(c->read + o) & (__name##_fifo_size-1)];\
143 static FIFO_INLINE void __name##_write_at(__name##_t *c, FIFO_CURSOR_TYPE o, __type b)\
145 c->buffer[(c->write + o) & (__name##_fifo_size-1)] = b;\
147 static FIFO_INLINE void __name##_write_offset(__name##_t *c, FIFO_CURSOR_TYPE o)\
149 c->write = (c->write + o) & (__name##_fifo_size-1);\
151 static FIFO_INLINE void __name##_reset(__name##_t *c)\
153 c->read = c->write = c->flags = 0;\