fifo: Add fifo_declare.h

My own implementation, used in countless projects

Signed-off-by: Michel Pollet <buserror@gmail.com>

src/common/fifo_declare.h

@@ -0,0 +1,189 @@
+/*
+	fido_declare.h
+	Copyright (C) 2003-2012 Michel Pollet <buserror@gmail.com>
+
+	This library is free software; you can redistribute it and/or
+	modify it under the terms of the GNU Lesser General Public
+	License as published by the Free Software Foundation; either
+	version 2.1 of the License, or (at your option) any later version.
+
+	This library is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+	Lesser General Public License for more details.
+
+	You should have received a copy of the GNU Lesser General Public
+	License along with this library; if not, write to the Free Software
+	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+/*
+ * FIFO helpers, aka circular buffers
+ *
+ * these macros define accessories for FIFOs of any name, type and
+ * any (power of two) size
+ */
+
+#ifndef __FIFO_DECLARE__
+#define __FIFO_DECLARE__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+	doing a :
+	DECLARE_FIFO(uint8_t, myfifo, 128);
+
+	will declare :
+	enum : myfifo_overflow_f
+	type : myfifo_t
+	functions:
+		// write a byte into the fifo, return 1 if there was room, 0 if there wasn't
+		int myfifo_write(myfifo_t *c, uint8_t b);
+		// reads a byte from the fifo, return 0 if empty. Use myfifo_isempty() to check beforehand
+		uint8_t myfifo_read(myfifo_t *c);
+		int myfifo_isfull(myfifo_t *c);
+		int myfifo_isempty(myfifo_t *c);
+		// returns number of items to read now
+		uint16_t myfifo_get_read_size(myfifo_t *c);
+		// read item at offset o from read cursor, no cursor advance
+		uint8_t myfifo_read_at(myfifo_t *c, uint16_t o);
+		// write b at offset o compared to current write cursor, no cursor advance
+		void myfifo_write_at(myfifo_t *c, uint16_t o, uint8_t b);
+
+	In your .c you need to 'implement' the fifo:
+	DEFINE_FIFO(uint8_t, myfifo)
+
+	To use the fifo, you must declare at least one :
+	myfifo_t fifo = FIFO_NULL;
+
+	while (!myfifo_isfull(&fifo))
+		myfifo_write(&fifo, 0xaa);
+	....
+	while (!myfifo_isempty(&fifo))
+		b = myfifo_read(&fifo);
+ */
+
+#include <stdint.h>
+
+#if __AVR__
+#define FIFO_CURSOR_TYPE	uint8_t
+#define FIFO_BOOL_TYPE	char
+#define FIFO_INLINE
+#define FIFO_SYNC
+#endif
+
+#ifndef	FIFO_CURSOR_TYPE
+#define FIFO_CURSOR_TYPE	uint16_t
+#endif
+#ifndef	FIFO_BOOL_TYPE
+#define FIFO_BOOL_TYPE	int
+#endif
+#ifndef	FIFO_INLINE
+#define FIFO_INLINE	inline
+#endif
+
+/* We should not need volatile */
+#ifndef FIFO_VOLATILE
+#define FIFO_VOLATILE
+#endif
+#ifndef FIFO_SYNC
+#define FIFO_SYNC __sync_synchronize()
+#endif
+
+#ifndef FIFO_ZERO_INIT
+#define FIFO_ZERO_INIT {0}
+#endif
+#define FIFO_NULL { FIFO_ZERO_INIT, 0, 0, 0 }
+
+/* New compilers don't like unused static functions. However,
+ * we do like 'static inlines' for these small accessors,
+ * so we mark them as 'unused'. It stops it complaining */
+#ifdef __GNUC__
+#define FIFO_DECL static __attribute__ ((unused))
+#else
+#define FIFO_DECL static
+#endif
+
+#define DECLARE_FIFO(__type, __name, __size) \
+enum { __name##_overflow_f = (1 << 0) }; \
+enum { __name##_fifo_size = (__size) }; \
+typedef struct __name##_t {			\
+	__type		buffer[__name##_fifo_size];		\
+	FIFO_VOLATILE FIFO_CURSOR_TYPE	read;		\
+	FIFO_VOLATILE FIFO_CURSOR_TYPE	write;		\
+	FIFO_VOLATILE uint8_t	flags;		\
+} __name##_t
+
+#define DEFINE_FIFO(__type, __name) \
+FIFO_DECL FIFO_INLINE FIFO_BOOL_TYPE __name##_write(__name##_t * c, __type b)\
+{\
+	FIFO_CURSOR_TYPE now = c->write;\
+	FIFO_CURSOR_TYPE next = (now + 1) & (__name##_fifo_size-1);\
+	if (c->read != next) {	\
+		c->buffer[now] = b;\
+		FIFO_SYNC; \
+		c->write = next;\
+		return 1;\
+	}\
+	return 0;\
+}\
+FIFO_DECL FIFO_INLINE FIFO_BOOL_TYPE __name##_isfull(__name##_t *c)\
+{\
+	FIFO_CURSOR_TYPE next = (c->write + 1) & (__name##_fifo_size-1);\
+	return c->read == next;\
+}\
+FIFO_DECL FIFO_INLINE FIFO_BOOL_TYPE __name##_isempty(__name##_t * c)\
+{\
+	return c->read == c->write;\
+}\
+FIFO_DECL FIFO_INLINE __type __name##_read(__name##_t * c)\
+{\
+	__type res = FIFO_ZERO_INIT; \
+	FIFO_CURSOR_TYPE read = c->read;\
+	if (read == c->write)\
+		return res;\
+	res = c->buffer[read];\
+	FIFO_SYNC; \
+	c->read = (read + 1) & (__name##_fifo_size-1);\
+	return res;\
+}\
+FIFO_DECL FIFO_INLINE FIFO_CURSOR_TYPE __name##_get_read_size(__name##_t *c)\
+{\
+	return ((c->write + __name##_fifo_size) - c->read) & (__name##_fifo_size-1);\
+}\
+FIFO_DECL FIFO_INLINE FIFO_CURSOR_TYPE __name##_get_write_size(__name##_t *c)\
+{\
+	return (__name##_fifo_size-1) - __name##_get_read_size(c);\
+}\
+FIFO_DECL FIFO_INLINE void __name##_read_offset(__name##_t *c, FIFO_CURSOR_TYPE o)\
+{\
+	FIFO_SYNC; \
+	c->read = (c->read + o) & (__name##_fifo_size-1);\
+}\
+FIFO_DECL FIFO_INLINE __type __name##_read_at(__name##_t *c, FIFO_CURSOR_TYPE o)\
+{\
+	return c->buffer[(c->read + o) & (__name##_fifo_size-1)];\
+}\
+FIFO_DECL FIFO_INLINE void __name##_write_at(__name##_t *c, FIFO_CURSOR_TYPE o, __type b)\
+{\
+	c->buffer[(c->write + o) & (__name##_fifo_size-1)] = b;\
+}\
+FIFO_DECL FIFO_INLINE void __name##_write_offset(__name##_t *c, FIFO_CURSOR_TYPE o)\
+{\
+	FIFO_SYNC; \
+	c->write = (c->write + o) & (__name##_fifo_size-1);\
+}\
+FIFO_DECL FIFO_INLINE void __name##_reset(__name##_t *c)\
+{\
+	FIFO_SYNC; \
+	c->read = c->write = c->flags = 0;\
+}\
+struct __name##_t
+
+#ifdef __cplusplus
+};
+#endif
+
+#endif