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[/] [zipcpu/] [trunk/] [rtl/] [peripherals/] [zipcounter.v] - Rev 181
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/////////////////////////////////////////////////////////////////////////// // // Filename: zipcounter.v // // Project: Zip CPU -- a small, lightweight, RISC CPU soft core // // Purpose: // A very, _very_ simple counter. It's purpose doesn't really // include rollover, but it will interrupt on rollover. It can be set, // although my design concept is that it can be reset. It cannot be // halted. It will always produce interrupts--whether or not they are // handled interrupts is another question--that's up to the interrupt // controller. // // My intention is to use this counter for process accounting: I should // be able to use this to count clock ticks of processor time assigned to // each task by resetting the counter at the beginning of every task // interval, and reading the result at the end of the interval. As long // as the interval is less than 2^32 clocks, there should be no problem. // Similarly, this can be used to measure CPU wishbone bus stalls, // prefetch stalls, or other CPU stalls (i.e. stalling as part of a JMP // instruction, or a read from the condition codes following a write). // // // Creator: Dan Gisselquist, Ph.D. // Gisselquist Technology, LLC // /////////////////////////////////////////////////////////////////////////// // // Copyright (C) 2015-2016, Gisselquist Technology, LLC // // This program is free software (firmware): you can redistribute it and/or // modify it under the terms of the GNU General Public License as published // by the Free Software Foundation, either version 3 of the License, or (at // your option) any later version. // // This program is distributed in the hope that it will be useful, but WITHOUT // ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License // for more details. // // License: GPL, v3, as defined and found on www.gnu.org, // http://www.gnu.org/licenses/gpl.html // // /////////////////////////////////////////////////////////////////////////// // module zipcounter(i_clk, i_ce, i_wb_cyc, i_wb_stb, i_wb_we, i_wb_data, o_wb_ack, o_wb_stall, o_wb_data, o_int); parameter BW = 32; input i_clk, i_ce; // Wishbone inputs input i_wb_cyc, i_wb_stb, i_wb_we; input [(BW-1):0] i_wb_data; // Wishbone outputs output reg o_wb_ack; output wire o_wb_stall; output reg [(BW-1):0] o_wb_data; // Interrupt line output reg o_int; initial o_int = 0; initial o_wb_data = 32'h00; always @(posedge i_clk) if ((i_wb_stb)&&(i_wb_we)) { o_int, o_wb_data } <= { 1'b0, i_wb_data }; else if (i_ce) { o_int, o_wb_data } <= o_wb_data+{{(BW-1){1'b0}},1'b1}; else o_int <= 1'b0; initial o_wb_ack = 1'b0; always @(posedge i_clk) o_wb_ack <= (i_wb_stb); assign o_wb_stall = 1'b0; endmodule
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