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/*
* Copyright (c) 2009-2013 Travis Geiselbrecht
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#pragma once
#include <compiler.h>
#include <sys/types.h>
#include <kernel/event.h>
#include <kernel/spinlock.h>
#include <iovec.h>
__BEGIN_CDECLS
typedef struct cbuf {
uint head;
uint tail;
uint len_pow2;
char *buf;
event_t event;
spin_lock_t lock;
} cbuf_t;
/**
* cbuf_initialize
*
* Initialize a cbuf structure, mallocing the underlying data buffer in the
* process. Make sure that the buffer has enough space for at least len bytes.
*
* @param[in] cbuf A pointer to the cbuf structure to allocate.
* @param[in] len The minimum number of bytes for the underlying data buffer.
*/
void cbuf_initialize(cbuf_t *cbuf, size_t len);
/**
* cbuf_initalize_etc
*
* Initialize a cbuf structure using the supplied buffer for internal storage.
*
* @param[in] cbuf A pointer to the cbuf structure to allocate.
* @param[in] len The size of the supplied buffer, in bytes.
* @param[in] buf A pointer to the memory to be used for internal storage.
*/
void cbuf_initialize_etc(cbuf_t *cbuf, size_t len, void *buf);
/**
* cbuf_read
*
* Read up to buflen bytes in to the supplied buffer.
*
* @param[in] cbuf The cbuf instance to read from.
* @param[in] buf A pointer to a buffer to read data into. If NULL, cbuf_read
* will skip up to the next buflen bytes from the cbuf.
* @param[in] buflen The maximum number of bytes to read from the cbuf.
* @param[in] block When true, will cause the caller to block until there is at
* least one byte available to read from the cbuf.
*
* @return The actual number of bytes which were read (or skipped).
*/
size_t cbuf_read(cbuf_t *cbuf, void *buf, size_t buflen, bool block);
/**
* cbuf_peek
*
* Peek at the data available for read in the cbuf right now. Does not actually
* consume the data, it just fills out a pair of iovec structures describing the
* (up to) two contiguous regions currently available for read.
*
* @param[in] cbuf The cbuf instance to write to.
* @param[out] A pointer to two iovec structures to hold the contiguous regions
* for read. NOTE: regions must point to a chunk of memory which is at least
* sizeof(iovec_t) * 2 bytes long.
*
* @return The number of bytes which were written (or skipped).
*/
size_t cbuf_peek(cbuf_t *cbuf, iovec_t *regions);
/**
* cbuf_write
*
* Write up to len bytes from the the supplied buffer into the cbuf.
*
* @param[in] cbuf The cbuf instance to write to.
* @param[in] buf A pointer to a buffer to read data from. If NULL, cbuf_write
* will skip up to the next len bytes in the cbuf, filling with zeros instead of
* supplied data.
* @param[in] len The maximum number of bytes to write to the cbuf.
* @param[in] canreschedule Rescheduling policy passed through to the internal
* event when signaling the event to indicate that there is now data in the
* buffer to be read.
*
* @return The number of bytes which were written (or skipped).
*/
size_t cbuf_write(cbuf_t *cbuf, const void *buf, size_t len, bool canreschedule);
/**
* cbuf_space_avail
*
* @param[in] cbuf The cbuf instance to query
*
* @return The number of free space available in the cbuf (IOW - the maximum
* number of bytes which can currently be written)
*/
size_t cbuf_space_avail(cbuf_t *cbuf);
/**
* cbuf_space_used
*
* @param[in] cbuf The cbuf instance to query
*
* @return The number of used bytes in the cbuf (IOW - the maximum number of
* bytes which can currently be read).
*/
size_t cbuf_space_used(cbuf_t *cbuf);
/**
* cbuf_size
*
* @param[in] cbuf The cbuf instance to query
*
* @return The size of the cbuf's underlying data buffer.
*/
static inline size_t cbuf_size(cbuf_t *cbuf)
{
return (1UL << cbuf->len_pow2);
}
/**
* cbuf_reset
*
* Reset the cbuf instance, discarding any data which may be in the buffer at
* the moment.
*
* @param[in] cbuf The cbuf instance to reset.
*/
static inline void cbuf_reset(cbuf_t *cbuf)
{
cbuf_read(cbuf, NULL, cbuf_size(cbuf), false);
}
/* special cases for dealing with a single char of data */
size_t cbuf_read_char(cbuf_t *cbuf, char *c, bool block);
size_t cbuf_write_char(cbuf_t *cbuf, char c, bool canreschedule);
__END_CDECLS
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