268 lines
8.1 KiB
C
268 lines
8.1 KiB
C
/******************************************************************************/
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/*!
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@file fifo.c
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@author hathach (tinyusb.org)
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@section DESCRIPTION
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Light-weight FIFO buffer with basic mutex support
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@section LICENSE
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Software License Agreement (BSD License)
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Copyright (c) 2012, K. Townsend (microBuilder.eu)
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. Neither the name of the copyright holders nor the
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names of its contributors may be used to endorse or promote products
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derived from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
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EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/******************************************************************************/
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#include "fifo.h"
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/*------------------------------------------------------------------*/
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/*
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*------------------------------------------------------------------*/
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#if CFG_FIFO_MUTEX
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#define mutex_lock_if_needed(_ff) if (_ff->mutex) fifo_mutex_lock(_ff->mutex)
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#define mutex_unlock_if_needed(_ff) if (_ff->mutex) fifo_mutex_unlock(_ff->mutex)
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#else
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#define mutex_lock_if_needed(_ff)
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#define mutex_unlock_if_needed(_ff)
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#endif
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static inline uint16_t min16_of(uint16_t x, uint16_t y)
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{
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return (x < y) ? x : y;
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}
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static inline bool fifo_initalized(fifo_t* f)
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{
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return (f->buffer != NULL) && (f->depth > 0) && (f->item_size > 0);
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}
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/******************************************************************************/
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/*!
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@brief Read one byte out of the RX buffer.
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This function will return the byte located at the array index of the
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read pointer, and then increment the read pointer index. If the read
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pointer exceeds the maximum buffer size, it will roll over to zero.
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@param[in] f
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Pointer to the FIFO buffer to manipulate
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@param[in] p_buffer
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Pointer to the place holder for data read from the buffer
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@returns TRUE if the queue is not empty
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*/
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/******************************************************************************/
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bool fifo_read(fifo_t* f, void * p_buffer)
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{
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if( !fifo_initalized(f) ) return false;
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if( fifo_empty(f) ) return false;
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mutex_lock_if_needed(f);
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memcpy(p_buffer,
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f->buffer + (f->rd_idx * f->item_size),
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f->item_size);
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f->rd_idx = (f->rd_idx + 1) % f->depth;
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f->count--;
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mutex_unlock_if_needed(f);
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return true;
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}
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/******************************************************************************/
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/*!
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@brief This function will read n elements into the array index specified by
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the write pointer and increment the write index. If the write index
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exceeds the max buffer size, then it will roll over to zero.
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@param[in] f
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Pointer to the FIFO buffer to manipulate
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@param[in] p_data
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The pointer to data location
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@param[in] count
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Number of element that buffer can afford
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@returns number of bytes read from the FIFO
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*/
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/******************************************************************************/
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uint16_t fifo_read_n (fifo_t* f, void * p_buffer, uint16_t count)
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{
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if( !fifo_initalized(f) ) return false;
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if( fifo_empty(f) ) return false;
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/* Limit up to fifo's count */
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count = min16_of(count, f->count);
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if( count == 0 ) return 0;
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mutex_lock_if_needed(f);
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/* Could copy up to 2 portions marked as 'x' if queue is wrapped around
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* case 1: ....RxxxxW.......
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* case 2: xxxxxW....Rxxxxxx
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*/
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// uint16_t index2upper = min16_of(count, f->count-f->rd_idx);
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uint8_t* p_buf = (uint8_t*) p_buffer;
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uint16_t len = 0;
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while( (len < count) && fifo_read(f, p_buf) )
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{
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len++;
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p_buf += f->item_size;
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}
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mutex_unlock_if_needed(f);
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return len;
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}
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/******************************************************************************/
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/*!
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@brief Reads one item without removing it from the FIFO
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@param[in] f
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Pointer to the FIFO buffer to manipulate
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@param[in] position
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Position to read from in the FIFO buffer
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@param[in] p_buffer
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Pointer to the place holder for data read from the buffer
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@returns TRUE if the queue is not empty
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*/
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/******************************************************************************/
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bool fifo_peek_at(fifo_t* f, uint16_t position, void * p_buffer)
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{
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if ( !fifo_initalized(f) ) return false;
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if ( position >= f->count ) return false;
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// rd_idx is position=0
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uint16_t index = (f->rd_idx + position) % f->depth;
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memcpy(p_buffer,
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f->buffer + (index * f->item_size),
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f->item_size);
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return true;
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}
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/******************************************************************************/
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/*!
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@brief Write one element into the RX buffer.
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This function will write one element into the array index specified by
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the write pointer and increment the write index. If the write index
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exceeds the max buffer size, then it will roll over to zero.
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@param[in] f
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Pointer to the FIFO buffer to manipulate
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@param[in] p_data
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The byte to add to the FIFO
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@returns TRUE if the data was written to the FIFO (overwrittable
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FIFO will always return TRUE)
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*/
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/******************************************************************************/
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bool fifo_write(fifo_t* f, void const * p_data)
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{
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if ( !fifo_initalized(f) ) return false;
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if ( fifo_full(f) && !f->overwritable ) return false;
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mutex_lock_if_needed(f);
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memcpy( f->buffer + (f->wr_idx * f->item_size),
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p_data,
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f->item_size);
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f->wr_idx = (f->wr_idx + 1) % f->depth;
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if (fifo_full(f))
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{
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f->rd_idx = f->wr_idx; // keep the full state (rd == wr && len = size)
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}
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else
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{
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f->count++;
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}
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mutex_unlock_if_needed(f);
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return true;
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}
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/******************************************************************************/
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/*!
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@brief This function will write n elements into the array index specified by
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the write pointer and increment the write index. If the write index
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exceeds the max buffer size, then it will roll over to zero.
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@param[in] f
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Pointer to the FIFO buffer to manipulate
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@param[in] p_data
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The pointer to data to add to the FIFO
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@param[in] count
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Number of element
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@return Number of written elements
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*/
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/******************************************************************************/
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uint16_t fifo_write_n(fifo_t* f, void const * p_data, uint16_t count)
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{
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if ( count == 0 ) return 0;
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uint8_t* p_buf = (uint8_t*) p_data;
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uint16_t len = 0;
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while( (len < count) && fifo_write(f, p_buf) )
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{
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len++;
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p_buf += f->item_size;
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}
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return len;
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}
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/******************************************************************************/
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/*!
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@brief Clear the fifo read and write pointers and set length to zero
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@param[in] f
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Pointer to the FIFO buffer to manipulate
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*/
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/******************************************************************************/
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void fifo_clear(fifo_t *f)
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{
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mutex_lock_if_needed(f);
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f->rd_idx = f->wr_idx = f->count = 0;
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mutex_unlock_if_needed(f);
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}
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