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rt-thread/bsp/samd21/sam_d2x_asflib/common/services/fifo/fifo.h

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/**
* \file
*
* \brief This file controls the software FIFO management.
*
* These functions manages FIFOs thanks to simple a API. The FIFO can
* be 100% full thanks to a double-index range implementation. For example,
* a FIFO of 4 elements can be implemented: the FIFO can really hold up to 4
* elements.
* This is particularly well suited for any kind of application needing a lot of
* small FIFO.
*
* Copyright (c) 2010-2015 Atmel Corporation. All rights reserved.
*
* \asf_license_start
*
* \page License
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The name of Atmel may not be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* 4. This software may only be redistributed and used in connection with an
* Atmel microcontroller product.
*
* THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
* EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* \asf_license_stop
*
*/
/*
* Support and FAQ: visit <a href="http://www.atmel.com/design-support/">Atmel Support</a>
*/
#ifndef _FIFO_H_
#define _FIFO_H_
#include "compiler.h"
/**
* \defgroup fifo_group First-In-First-Out Buffer (FIFO)
*
* See \ref fifo_quickstart.
*
* These functions manages FIFOs thanks to simple a API. The FIFO can
* be 100% full thanks to a double-index range implementation. For example,
* a FIFO of 4 elements can be implemented: the FIFO can really hold up to 4
* elements. This is particularly well suited for any kind of application
* needing a lot of small FIFO. The maximum fifo size is 128 items (uint8,
* uint16 or uint32). Note that the driver, thanks to its conception, does
* not use interrupt protection.
*
* @{
*/
//! Error codes used by FIFO driver.
enum {
FIFO_OK = 0, //!< Normal operation.
FIFO_ERROR_OVERFLOW, //!< Attempt to push something in a FIFO that is full.
FIFO_ERROR_UNDERFLOW, //!< Attempt to pull something from a FIFO that is empty
FIFO_ERROR, //!< Error condition during FIFO initialization
};
//! FIFO descriptor used by FIFO driver.
struct fifo_desc {
union
{
uint32_t *u32ptr; //!< Pointer to unsigned-32 bits location
uint16_t *u16ptr; //!< Pointer to unsigned-16 bits location
uint8_t *u8ptr; //!< Pointer to unsigned-8 bits location
} buffer;
volatile uint8_t read_index; //!< Read index
volatile uint8_t write_index; //!< Write index
uint8_t size; //!< Size of the FIFO (unit is in number of 'element')
uint8_t mask; //!< Mask used to speed up FIFO operation (wrapping)
};
typedef struct fifo_desc fifo_desc_t;
/**
* \brief Initializes a new software FIFO for a certain 'size'.
*
* \pre Both fifo descriptor and buffer must be allocated by the caller before.
*
* \param fifo_desc Pointer on the FIFO descriptor.
* \param buffer Pointer on the FIFO buffer.
* \param size Size of the buffer (unit is in number of 'elements').
* It must be a 2-power and <= to 128.
*
* \return Status
* \retval FIFO_OK when no error occurred.
* \retval FIFO_ERROR when the size is not a 2-power.
*/
int fifo_init(fifo_desc_t *fifo_desc, void *buffer, uint8_t size);
/**
* \brief Returns the number of elements in the FIFO.
*
* \param fifo_desc The FIFO descriptor.
*
* \return The number of used elements.
*/
static inline uint8_t fifo_get_used_size(fifo_desc_t *fifo_desc)
{
return ((fifo_desc->write_index - fifo_desc->read_index) & fifo_desc->mask);
}
/**
* \brief Returns the remaining free spaces of the FIFO (in number of elements).
*
* \param fifo_desc The FIFO descriptor.
*
* \return The number of free elements.
*/
static inline uint8_t fifo_get_free_size(fifo_desc_t *fifo_desc)
{
return fifo_desc->size - fifo_get_used_size(fifo_desc);
}
/**
* \brief Tests if a FIFO is empty.
*
* \param fifo_desc The FIFO descriptor.
*
* \return Status
* \retval true when the FIFO is empty.
* \retval false when the FIFO is not empty.
*/
static inline bool fifo_is_empty(fifo_desc_t *fifo_desc)
{
return (fifo_desc->write_index == fifo_desc->read_index);
}
/**
* \brief Tests if a FIFO is full.
*
* \param fifo_desc The FIFO descriptor.
*
* \return Status
* \retval true when the FIFO is full.
* \retval false when the FIFO is not full.
*/
static inline bool fifo_is_full(fifo_desc_t *fifo_desc)
{
return (fifo_get_used_size(fifo_desc) == fifo_desc->size);
}
/**
* \brief Puts a new 8-bits element into the FIFO.
*
* \param fifo_desc The FIFO descriptor.
* \param item extracted element.
*/
static inline void fifo_push_uint8_nocheck(fifo_desc_t *fifo_desc, uint32_t item)
{
uint8_t write_index;
write_index = fifo_desc->write_index;
fifo_desc->buffer.u8ptr[write_index & (fifo_desc->mask >> 1)] = item;
write_index = (write_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->write_index = write_index;
}
/**
* \brief Puts a new 8-bits element into the FIFO and
* checks for a possible overflow.
*
* \param fifo_desc The FIFO descriptor.
* \param item extracted element.
*
* \return Status
* \retval FIFO_OK when no error occurred.
* \retval FIFO_ERROR_UNDERFLOW when the FIFO was empty.
*/
static inline int fifo_push_uint8(fifo_desc_t *fifo_desc, uint32_t item)
{
uint8_t write_index;
if (fifo_is_full(fifo_desc)) {
return FIFO_ERROR_OVERFLOW;
}
write_index = fifo_desc->write_index;
fifo_desc->buffer.u8ptr[write_index & (fifo_desc->mask >> 1)] = item;
write_index = (write_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->write_index = write_index;
return FIFO_OK;
}
/**
* \brief Puts a new 16-bits element into the FIFO.
*
* \param fifo_desc The FIFO descriptor.
* \param item extracted element.
*/
static inline void fifo_push_uint16_nocheck(fifo_desc_t *fifo_desc, uint32_t item)
{
uint8_t write_index;
write_index = fifo_desc->write_index;
fifo_desc->buffer.u16ptr[write_index & (fifo_desc->mask >> 1)] = item;
write_index = (write_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->write_index = write_index;
}
/**
* \brief Puts a new 16-bits element into the FIFO and
* checks for a possible overflow.
*
* \param fifo_desc The FIFO descriptor.
* \param item extracted element.
*
* \return Status
* \retval FIFO_OK when no error occurred.
* \retval FIFO_ERROR_UNDERFLOW when the FIFO was empty.
*/
static inline int fifo_push_uint16(fifo_desc_t *fifo_desc, uint32_t item)
{
uint8_t write_index;
if (fifo_is_full(fifo_desc)) {
return FIFO_ERROR_OVERFLOW;
}
write_index = fifo_desc->write_index;
fifo_desc->buffer.u16ptr[write_index & (fifo_desc->mask >> 1)] = item;
write_index = (write_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->write_index = write_index;
return FIFO_OK;
}
/**
* \brief Puts a new 32-bits element into the FIFO.
*
* \param fifo_desc The FIFO descriptor.
* \param item extracted element.
*/
static inline void fifo_push_uint32_nocheck(fifo_desc_t *fifo_desc, uint32_t item)
{
uint8_t write_index;
write_index = fifo_desc->write_index;
fifo_desc->buffer.u32ptr[write_index & (fifo_desc->mask >> 1)] = item;
write_index = (write_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->write_index = write_index;
}
/**
* \brief Puts a new 32-bits element into the FIFO and
* checks for a possible overflow.
*
* \param fifo_desc The FIFO descriptor.
* \param item extracted element.
*
* \return Status
* \retval FIFO_OK when no error occurred.
* \retval FIFO_ERROR_UNDERFLOW when the FIFO was empty.
*/
static inline int fifo_push_uint32(fifo_desc_t *fifo_desc, uint32_t item)
{
uint8_t write_index;
if (fifo_is_full(fifo_desc)) {
return FIFO_ERROR_OVERFLOW;
}
write_index = fifo_desc->write_index;
fifo_desc->buffer.u32ptr[write_index & (fifo_desc->mask >> 1)] = item;
write_index = (write_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->write_index = write_index;
return FIFO_OK;
}
/**
* \brief Gets a 8-bits element from the FIFO.
*
* \param fifo_desc The FIFO descriptor.
*
* \return extracted element.
*/
static inline uint8_t fifo_pull_uint8_nocheck(fifo_desc_t *fifo_desc)
{
uint8_t read_index;
uint8_t item;
read_index = fifo_desc->read_index;
item = fifo_desc->buffer.u8ptr[read_index & (fifo_desc->mask >> 1)];
read_index = (read_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->read_index = read_index;
return item;
}
/**
* \brief Gets a 8-bits element from the FIFO and
* checks for a possible underflow.
*
* \param fifo_desc The FIFO descriptor.
* \param item extracted element.
*
* \return Status
* \retval FIFO_OK when no error occurred.
* \retval FIFO_ERROR_UNDERFLOW when the FIFO was empty.
*/
static inline int fifo_pull_uint8(fifo_desc_t *fifo_desc, uint8_t *item)
{
uint8_t read_index;
if (fifo_is_empty(fifo_desc)) {
return FIFO_ERROR_UNDERFLOW;
}
read_index = fifo_desc->read_index;
*item = fifo_desc->buffer.u8ptr[read_index & (fifo_desc->mask >> 1)];
read_index = (read_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->read_index = read_index;
return FIFO_OK;
}
/**
* \brief Gets a 16-bits element from the FIFO.
*
* \param fifo_desc The FIFO descriptor.
*
* \return extracted element.
*/
static inline uint16_t fifo_pull_uint16_nocheck(fifo_desc_t *fifo_desc)
{
uint8_t read_index;
uint16_t item;
read_index = fifo_desc->read_index;
item = fifo_desc->buffer.u16ptr[read_index & (fifo_desc->mask >> 1)];
read_index = (read_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->read_index = read_index;
return item;
}
/**
* \brief Gets a 16-bits element from the FIFO and
* checks for a possible underflow.
*
* \param fifo_desc The FIFO descriptor.
* \param item extracted element.
*
* \return Status
* \retval FIFO_OK when no error occurred.
* \retval FIFO_ERROR_UNDERFLOW when the FIFO was empty.
*/
static inline int fifo_pull_uint16(fifo_desc_t *fifo_desc, uint16_t *item)
{
uint8_t read_index;
if (fifo_is_empty(fifo_desc)) {
return FIFO_ERROR_UNDERFLOW;
}
read_index = fifo_desc->read_index;
*item = fifo_desc->buffer.u16ptr[read_index & (fifo_desc->mask >> 1)];
read_index = (read_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->read_index = read_index;
return FIFO_OK;
}
/**
* \brief Gets a 32-bits element from the FIFO
*
* \param fifo_desc The FIFO descriptor.
*
* \return extracted element.
*/
static inline uint32_t fifo_pull_uint32_nocheck(fifo_desc_t *fifo_desc)
{
uint8_t read_index;
uint32_t item;
read_index = fifo_desc->read_index;
item = fifo_desc->buffer.u32ptr[read_index & (fifo_desc->mask >> 1)];
read_index = (read_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->read_index = read_index;
return item;
}
/**
* \brief Gets a 32-bits element from the FIFO and
* checks for a possible underflow.
*
* \param fifo_desc The FIFO descriptor.
* \param item extracted element.
*
* \return Status
* \retval FIFO_OK when no error occurred.
* \retval FIFO_ERROR_UNDERFLOW when the FIFO was empty.
*/
static inline int fifo_pull_uint32(fifo_desc_t *fifo_desc, uint32_t *item)
{
uint8_t read_index;
if (fifo_is_empty(fifo_desc)) {
return FIFO_ERROR_UNDERFLOW;
}
read_index = fifo_desc->read_index;
*item = fifo_desc->buffer.u32ptr[read_index & (fifo_desc->mask >> 1)];
read_index = (read_index + 1) & fifo_desc->mask;
// Must be the last thing to do.
barrier();
fifo_desc->read_index = read_index;
return FIFO_OK;
}
/**
* \brief Gets a 32-bits element from the FIFO but does
* not remove it from the FIFO.
*
* \param fifo_desc The FIFO descriptor.
*
* \retval item extracted element.
*/
static inline uint32_t fifo_peek_uint32(fifo_desc_t *fifo_desc)
{
return fifo_desc->buffer.u32ptr[fifo_desc->read_index & (fifo_desc->mask >> 1)];
}
/**
* \brief Gets a 16-bits element from the FIFO but does
* not remove it from the FIFO.
*
* \param fifo_desc The FIFO descriptor.
*
* \retval item extracted element.
*/
static inline uint16_t fifo_peek_uint16(fifo_desc_t *fifo_desc)
{
return fifo_desc->buffer.u16ptr[fifo_desc->read_index & (fifo_desc->mask >> 1)];
}
/**
* \brief Gets a 8-bits element from the FIFO but does
* not remove it from the FIFO.
*
* \param fifo_desc The FIFO descriptor.
*
* \retval item extracted element.
*/
static inline uint8_t fifo_peek_uint8(fifo_desc_t *fifo_desc)
{
return fifo_desc->buffer.u8ptr[fifo_desc->read_index & (fifo_desc->mask >> 1)];
}
/**
* \brief Flushes a software FIFO.
*
* \param fifo_desc The FIFO descriptor.
*/
static inline void fifo_flush(fifo_desc_t *fifo_desc)
{
// Fifo starts empty.
fifo_desc->read_index = fifo_desc->write_index = 0;
}
/**
* @}
*/
/**
* \page fifo_quickstart Quick start guide for First-In-First-Out Buffer (FIFO)
*
* This is the quick start guide for the \ref fifo_group, with
* step-by-step instructions on how to configure and use the driver in a
* selection of use cases.
*
* The use cases contain several code fragments. The code fragments in the
* steps for setup can be copied into a custom initialization function, while
* the steps for usage can be copied into, e.g., the main application function.
*
* \section fifo_use_cases FIFO use cases
* - \ref fifo_basic_use_case
* - \subpage fifo_use_case_1
*
* \section fifo_basic_use_case Basic use case - Push and pull
* In this use case, an element will be pushed to the FIFO, and the same
* element will be pulled from it.
*
* \section fifo_basic_use_case_setup Setup steps
*
* \subsection fifo_basic_use_case_setup_code Example code
* The following must be added to the project:
* \code
#define FIFO_BUFFER_LENGTH 4
#define PUSH_VALUE 0x12345678
union buffer_element {
uint8_t byte;
uint16_t halfword;
uint32_t word;
};
\endcode
*
* Add to application initialization:
* \code
union buffer_element fifo_buffer[FIFO_BUFFER_LENGTH];
fifo_desc_t fifo_desc;
fifo_init(&fifo_desc, fifo_buffer, FIFO_BUFFER_LENGTH);
\endcode
*
* \subsection fifo_basic_use_case_setup_flow Workflow
* -# Create a FIFO buffer of FIFO_BUFFER_LENGTH elements, capable
* of holding a byte, halfword or word:
* - \code union buffer_element fifo_buffer[FIFO_BUFFER_LENGTH]; \endcode
* -# Create a FIFO buffer descriptor that contains information about the
* location of the FIFO buffer, its size and where to read from or write to
* upon the next buffer pull or push:
* - \code fifo_desc_t fifo_desc; \endcode
* -# Initialize the FIFO:
* - \code fifo_init(&fifo_desc, fifo_buffer, FIFO_BUFFER_LENGTH); \endcode
*
* \section fifo_basic_use_case_usage Usage steps
*
* \subsection fifo_basic_use_case_usage_code Example code
* Add to application C-file:
* \code
uint8_t status;
uint8_t pull_value;
status = fifo_push_uint8(&fifo_desc, PUSH_VALUE & 0xff);
status = fifo_pull_uint8(&fifo_desc, &pull_value);
\endcode
*
* \subsection fifo_basic_use_case_usage_flow Workflow
* -# Create a variable to hold the return status from the FIFO:
* - \code uint8_t status; \endcode
* -# Create a variable to hold the pulled value from the FIFO:
* - \code uint8_t pull_value; \endcode
* -# Put a new 8-bit element into the FIFO:
* - \code status = fifo_push_uint8(&fifo_desc, PUSH_VALUE & 0xff); \endcode
* \note The status variable will contain \ref FIFO_OK if no error occurred.
* -# Get the 8-bit element from the FIFO:
* - \code status = fifo_pull_uint8(&fifo_desc, &pull_value); \endcode
* \note The status variable will contain \ref FIFO_OK if no error occurred.
*/
/**
* \page fifo_use_case_1 Push and flush
*
* In this use case, two elements will be pushed to the FIFO, and the FIFO
* will be flushed.
*
* \section fifo_use_case_1_setup Setup steps
*
* \subsection fifo_use_case_1_setup_code Example code
* The following must be added to the project:
* \code
#define FIFO_BUFFER_LENGTH 4
#define PUSH_VALUE 0x12345678
union buffer_element {
uint8_t byte;
uint16_t halfword;
uint32_t word;
};
\endcode
*
* Add to application initialization:
* \code
union buffer_element fifo_buffer[FIFO_BUFFER_LENGTH];
fifo_desc_t fifo_desc;
fifo_init(&fifo_desc, fifo_buffer, FIFO_BUFFER_LENGTH);
\endcode
*
* \subsection fifo_use_case_1_setup_flow Workflow
* -# Create a FIFO buffer of FIFO_BUFFER_LENGTH elements, capable
* of holding a byte, halfword or word:
* - \code union buffer_element fifo_buffer[FIFO_BUFFER_LENGTH]; \endcode
* -# Create a FIFO buffer descriptor that containing information about the
* location of the FIFO buffer, its size and where to read from or write to
* upon the next buffer pull or push:
* - \code fifo_desc_t fifo_desc; \endcode
* -# Initialize the FIFO:
* - \code fifo_init(&fifo_desc, fifo_buffer, FIFO_BUFFER_LENGTH); \endcode
* \section fifo_use_case_1_usage Usage steps
*
* \subsection fifo_use_case_1_usage_code Example code
* Add to application C-file:
* \code
uint8_t status;
bool fifo_empty;
status = fifo_push_uint16(&fifo_desc, PUSH_VALUE & 0xffff);
status = fifo_push_uint16(&fifo_desc, PUSH_VALUE & 0xffff);
fifo_flush(&fifo_desc);
fifo_empty = fifo_is_empty(&fifo_desc);
\endcode
*
* \subsection fifo_use_case_1_usage_flow Workflow
* -# Create a variable to hold the return status from the FIFO:
* - \code uint8_t status; \endcode
* -# Create a variable to hold the pulled value from the FIFO:
* - \code uint16_t pull_value; \endcode
* -# Put two new 16-bit element into the FIFO:
* - \code status = fifo_push_uint16(&fifo_desc, PUSH_VALUE & 0xffff); \endcode
* - \code status = fifo_push_uint16(&fifo_desc, PUSH_VALUE & 0xffff); \endcode
* \note The status variable will contain \ref FIFO_OK if no error occurred.
* -# Flush the FIFO:
* - \code fifo_flush(&fifo_desc); \endcode
* -# Check that the FIFO is empty after flushing:
* - \code fifo_empty = fifo_is_empty(&fifo_desc); \endcode
* \note The fifo_empty variable will be true if the FIFO is empty.
*/
#endif // _FIFO_H_
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