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/////////////////////////////////////////////////////////////////////
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//// ////
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//// WISHBONE AC 97 Controller ////
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//// DMA Request Module ////
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//// ////
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//// ////
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//// Author: Rudolf Usselmann ////
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//// rudi@asics.ws ////
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//// ////
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//// ////
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//// Downloaded from: http://www.opencores.org/cores/ac97_ctrl/ ////
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//// ////
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/////////////////////////////////////////////////////////////////////
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//// ////
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//// Copyright (C) 2001 Rudolf Usselmann ////
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//// rudi@asics.ws ////
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//// ////
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//// This source file may be used and distributed without ////
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//// restriction provided that this copyright statement is not ////
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//// removed from the file and that any derivative work contains ////
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//// the original copyright notice and the associated disclaimer.////
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//// ////
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//// THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY ////
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//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED ////
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//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS ////
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//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR ////
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//// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, ////
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//// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES ////
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//// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE ////
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//// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR ////
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//// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF ////
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//// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ////
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//// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT ////
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//// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE ////
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//// POSSIBILITY OF SUCH DAMAGE. ////
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//// ////
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/////////////////////////////////////////////////////////////////////
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// CVS Log
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//
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// $Id: ac97_dma_req.v,v 1.1 2001-08-03 06:54:49 rudi Exp $
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//
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// $Date: 2001-08-03 06:54:49 $
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// $Revision: 1.1 $
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// $Author: rudi $
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// $Locker: $
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// $State: Exp $
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//
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// Change History:
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// $Log: not supported by cvs2svn $
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// Revision 1.1.1.1 2001/05/19 02:29:16 rudi
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// Initial Checkin
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//
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//
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//
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//
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`include "ac97_defines.v"
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module ac97_dma_req(clk, rst, cfg, status, full_empty, dma_req, dma_ack);
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input clk, rst;
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input [7:0] cfg;
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input [1:0] status;
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input full_empty;
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output dma_req;
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input dma_ack;
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////////////////////////////////////////////////////////////////////
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//
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// Local Wires
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//
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reg dma_req_d;
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reg dma_req_r1;
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reg dma_req;
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////////////////////////////////////////////////////////////////////
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//
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// Misc Logic
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//
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always @(cfg or status or full_empty)
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case(cfg[5:4]) // synopsys parallel_case full_case
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// REQ = Ch_EN & DMA_EN & Status
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// 1/4 full/empty
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0: dma_req_d = cfg[0] & cfg[6] & (full_empty | (status == 2'd0));
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// 1/2 full/empty
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1: dma_req_d = cfg[0] & cfg[6] & (full_empty | (status[1] == 1'd0));
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// 3/4 full/empty
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2: dma_req_d = cfg[0] & cfg[6] & (full_empty | (status < 2'd3));
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3: dma_req_d = cfg[0] & cfg[6] & full_empty;
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endcase
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always @(posedge clk)
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dma_req_r1 <= #1 dma_req_d & !dma_ack;
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always @(posedge clk or negedge rst)
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if(!rst) dma_req <= #1 0;
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else
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if(dma_req_r1 & dma_req_d & !dma_ack) dma_req <= #1 1;
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else
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if(dma_ack) dma_req <= #1 0;
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endmodule
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