Subversion Repositories an-fpga-implementation-of-low-latency-noc-based-mpsoc

/*

 * Copyright (c) 2009-2014, IETR/INSA of Rennes

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are met:

 *

 *   * Redistributions of source code must retain the above copyright notice,

 *     this list of conditions and the following disclaimer.

 *   * 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.

 *   * Neither the name of the IETR/INSA of Rennes nor the names of its

 *     contributors may be used to endorse or promote products derived from this

 *     software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS 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,

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 * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 */

/**

 * Ring-buffer FIFO structure

 * Lock-free and cache-efficient implementation

 * Supports 1 producer - N consumers

 */

#define UNUSED_VAR     __attribute__ ((unused))

typedef struct {

    volatile char padding0[CACHELINE_SIZE]; /** Memory padding */

    unsigned int* read_inds;                /** Current reading positions */

    volatile char padding1[CACHELINE_SIZE]; /** Memory padding */

    unsigned int write_ind;                 /** Current writing position */

    volatile char padding2[CACHELINE_SIZE]; /** Memory padding */

    T *contents;                            /** Buffer containing the FIFO's elements */

} FIFO_T(T);

UNUSED_VAR static int FIFO_GET_NUM_TOKENS(T)(FIFO_T(T) *fifo, int reader_id) {

    return fifo->write_ind - fifo->read_inds[reader_id];

}

UNUSED_VAR static int FIFO_GET_ROOM(T)(FIFO_T(T) *fifo, int nb_readers, int size) {

    int i;

    int num_tokens, max_num_tokens = 0;

   for (i = 0; i < nb_readers; i++) {

        num_tokens = fifo->write_ind - fifo->read_inds[i];

        max_num_tokens = max_num_tokens > num_tokens ? max_num_tokens : num_tokens;

    }

    return size - max_num_tokens;

}