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author | Stefani Seibold <stefani@seibold.net> | 2009-12-21 14:37:30 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-22 14:17:56 -0800 |
commit | 37bdfbbfaab47811fcec84dff23c4e8da1a09f9e (patch) | |
tree | 89e88b5859674b9d9255fa1a87aaf34090da574d | |
parent | 9842c38e917636fa7dc6b88aff17a8f1fd7f0cc0 (diff) | |
download | op-kernel-dev-37bdfbbfaab47811fcec84dff23c4e8da1a09f9e.zip op-kernel-dev-37bdfbbfaab47811fcec84dff23c4e8da1a09f9e.tar.gz |
kfifo: add DEFINE_KFIFO and friends, add very tiny functions
Add DECLARE_KFIFO - macro to declare a kfifo and the associated buffer inside a struct
Add INIT_KFIFO - Initialize a kfifo declared by DECLARED_KFIFO
Add DEFINE_KFIFO - macro to define and initialize a kfifo as a global or local object
Add kfifo_size() - returns the size of the fifo in bytes
Add kfifo_is_empty() - returns true if the fifo is empty
Add kfifo_is_full() - returns true if the fifo is full
Add kfifo_avail() - returns the number of bytes available in the FIFO
Do some code cleanup
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | include/linux/kfifo.h | 94 |
1 files changed, 92 insertions, 2 deletions
diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h index 5ed2565..dd53eed 100644 --- a/include/linux/kfifo.h +++ b/include/linux/kfifo.h @@ -51,6 +51,60 @@ struct kfifo { unsigned int out; /* data is extracted from off. (out % size) */ }; +/* + * Macros for declaration and initialization of the kfifo datatype + */ + +/* helper macro */ +#define __kfifo_initializer(s, b) \ + (struct kfifo) { \ + .size = s, \ + .in = 0, \ + .out = 0, \ + .buffer = b \ + } + +/** + * DECLARE_KFIFO - macro to declare a kfifo and the associated buffer + * @name: name of the declared kfifo datatype + * @size: size of the fifo buffer + * + * Note: the macro can be used inside struct or union declaration + * Note: the macro creates two objects: + * A kfifo object with the given name and a buffer for the kfifo + * object named name##kfifo_buffer + */ +#define DECLARE_KFIFO(name, size) \ +union { \ + struct kfifo name; \ + unsigned char name##kfifo_buffer[size + sizeof(struct kfifo)]; \ +} + +/** + * INIT_KFIFO - Initialize a kfifo declared by DECLARED_KFIFO + * @name: name of the declared kfifo datatype + * @size: size of the fifo buffer + */ +#define INIT_KFIFO(name) \ + name = __kfifo_initializer(sizeof(name##kfifo_buffer) - \ + sizeof(struct kfifo), name##kfifo_buffer) + +/** + * DEFINE_KFIFO - macro to define and initialize a kfifo + * @name: name of the declared kfifo datatype + * @size: size of the fifo buffer + * + * Note: the macro can be used for global and local kfifo data type variables + * Note: the macro creates two objects: + * A kfifo object with the given name and a buffer for the kfifo + * object named name##kfifo_buffer + */ +#define DEFINE_KFIFO(name, size) \ + unsigned char name##kfifo_buffer[size]; \ + struct kfifo name = __kfifo_initializer(size, name##kfifo_buffer) + +#undef __kfifo_initializer + extern void kfifo_init(struct kfifo *fifo, unsigned char *buffer, unsigned int size); extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size, @@ -71,6 +125,15 @@ static inline void kfifo_reset(struct kfifo *fifo) } /** + * kfifo_size - returns the size of the fifo in bytes + * @fifo: the fifo to be used. + */ +static inline __must_check unsigned int kfifo_size(struct kfifo *fifo) +{ + return fifo->size; +} + +/** * kfifo_len - returns the number of used bytes in the FIFO * @fifo: the fifo to be used. */ @@ -84,6 +147,33 @@ static inline unsigned int kfifo_len(struct kfifo *fifo) } /** + * kfifo_is_empty - returns true if the fifo is empty + * @fifo: the fifo to be used. + */ +static inline __must_check int kfifo_is_empty(struct kfifo *fifo) +{ + return fifo->in == fifo->out; +} + +/** + * kfifo_is_full - returns true if the fifo is full + * @fifo: the fifo to be used. + */ +static inline __must_check int kfifo_is_full(struct kfifo *fifo) +{ + return kfifo_len(fifo) == kfifo_size(fifo); +} + +/** + * kfifo_avail - returns the number of bytes available in the FIFO + * @fifo: the fifo to be used. + */ +static inline __must_check unsigned int kfifo_avail(struct kfifo *fifo) +{ + return kfifo_size(fifo) - kfifo_len(fifo); +} + +/** * kfifo_in_locked - puts some data into the FIFO using a spinlock for locking * @fifo: the fifo to be used. * @from: the data to be added. @@ -133,8 +223,8 @@ static inline __must_check unsigned int kfifo_out_locked(struct kfifo *fifo, * optimization: if the FIFO is empty, set the indices to 0 * so we don't wrap the next time */ - if (fifo->in == fifo->out) - fifo->in = fifo->out = 0; + if (kfifo_is_empty(fifo)) + kfifo_reset(fifo); spin_unlock_irqrestore(lock, flags); |