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//
// Copyright 2011 Ettus Research LLC
//
// This program is free software: 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
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
// up to 8 semaphores
// After a read operation, the semaphore is always locked
// If it was already locked before the read (meaning someone else holds the lock)
// then a 1 is returned
// If it was not already locked (meaning the reader now holds the lock)
// then a 0 is returned
// A write operation clears the lock
module wb_semaphore
#(parameter count=8, DBUS_WIDTH=32)
(input wb_clk_i,
input wb_rst_i,
input [DBUS_WIDTH-1:0] wb_dat_i,
input [2:0] wb_adr_i,
input wb_cyc_i,
input wb_stb_i,
input wb_we_i,
output wb_ack_o,
output [DBUS_WIDTH-1:0] wb_dat_o);
reg [count-1:0] locked;
always @(posedge clock)
if(wb_rst_i)
locked <= {count{1'b0}};
else if(wb_stb_i)
if(wb_we_i)
locked[adr_i] <= 1'b0;
else
locked[adr_i] <= 1'b1;
assign wb_dat_o[DBUS_WIDTH-1:1] = {(DBUS_WIDTH-1){1'b0}};
assign wb_dat_o[0] = locked[adr_i];
assign wb_ack_o = wb_stb_i;
endmodule // wb_semaphore
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