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Diffstat (limited to 'rtl/modular/modular_subtractor.v')
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diff --git a/rtl/modular/modular_subtractor.v b/rtl/modular/modular_subtractor.v deleted file mode 100644 index 1637f45..0000000 --- a/rtl/modular/modular_subtractor.v +++ /dev/null @@ -1,292 +0,0 @@ -//------------------------------------------------------------------------------ -// -// modular_subtractor.v -// ----------------------------------------------------------------------------- -// Modular subtractor. -// -// Authors: Pavel Shatov -// -// Copyright (c) 2016, NORDUnet A/S -// -// 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 NORDUnet 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 HOLDER 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, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) -// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE -// POSSIBILITY OF SUCH DAMAGE. -// -//------------------------------------------------------------------------------ - -module modular_subtractor - ( - clk, rst_n, - ena, rdy, - ab_addr, n_addr, d_addr, d_wren, - a_din, b_din, n_din, d_dout - ); - - - // - // Parameters - // - parameter OPERAND_NUM_WORDS = 8; - parameter WORD_COUNTER_WIDTH = 3; - - - // - // Handy Numbers - // - localparam [WORD_COUNTER_WIDTH-1:0] WORD_INDEX_ZERO = 0; - localparam [WORD_COUNTER_WIDTH-1:0] WORD_INDEX_LAST = OPERAND_NUM_WORDS - 1; - - - // - // Handy Functions - // - function [WORD_COUNTER_WIDTH-1:0] WORD_INDEX_NEXT_OR_ZERO; - input [WORD_COUNTER_WIDTH-1:0] WORD_INDEX_CURRENT; - begin - WORD_INDEX_NEXT_OR_ZERO = (WORD_INDEX_CURRENT < WORD_INDEX_LAST) ? - WORD_INDEX_CURRENT + 1'b1 : WORD_INDEX_ZERO; - end - endfunction - - - // - // Ports - // - input wire clk; // system clock - input wire rst_n; // active-low async reset - - input wire ena; // enable input - output wire rdy; // ready output - - output wire [WORD_COUNTER_WIDTH-1:0] ab_addr; // index of current A and B words - output wire [WORD_COUNTER_WIDTH-1:0] n_addr; // index of current N word - output wire [WORD_COUNTER_WIDTH-1:0] d_addr; // index of current D word - output wire d_wren; // store current D word now - - input wire [ 31:0] a_din; // A - input wire [ 31:0] b_din; // B - input wire [ 31:0] n_din; // N - output wire [ 31:0] d_dout; // D = (A - B) mod N - - - // - // Word Indices - // - reg [WORD_COUNTER_WIDTH-1:0] index_ab; - reg [WORD_COUNTER_WIDTH-1:0] index_n; - reg [WORD_COUNTER_WIDTH-1:0] index_d; - - /* map registers to output ports */ - assign ab_addr = index_ab; - assign n_addr = index_n; - assign d_addr = index_d; - - - // - // Subtractor - // - wire [31: 0] sub32_d; - wire sub32_b_in; - wire sub32_b_out; - - subtractor32_wrapper subtractor32 - ( - .clk (clk), - .a (a_din), - .b (b_din), - .d (sub32_d), - .b_in (sub32_b_in), - .b_out (sub32_b_out) - ); - - - // - // Adder - // - wire [31: 0] add32_s; - wire add32_c_in; - wire add32_c_out; - - adder32_wrapper adder32 - ( - .clk (clk), - .a (sub32_d), - .b (n_din), - .s (add32_s), - .c_in (add32_c_in), - .c_out (add32_c_out) - ); - - - // - // FSM - // - - localparam FSM_SHREG_WIDTH = 2*OPERAND_NUM_WORDS + 5; - - reg [FSM_SHREG_WIDTH-1:0] fsm_shreg; - - assign rdy = fsm_shreg[0]; - - wire [OPERAND_NUM_WORDS-1:0] fsm_shreg_inc_index_ab = fsm_shreg[FSM_SHREG_WIDTH - (0 * OPERAND_NUM_WORDS + 1) : FSM_SHREG_WIDTH - (1 * OPERAND_NUM_WORDS + 0)]; - wire [OPERAND_NUM_WORDS-1:0] fsm_shreg_inc_index_n = fsm_shreg[FSM_SHREG_WIDTH - (0 * OPERAND_NUM_WORDS + 2) : FSM_SHREG_WIDTH - (1 * OPERAND_NUM_WORDS + 1)]; - wire [OPERAND_NUM_WORDS-1:0] fsm_shreg_store_dif_ab = fsm_shreg[FSM_SHREG_WIDTH - (0 * OPERAND_NUM_WORDS + 3) : FSM_SHREG_WIDTH - (1 * OPERAND_NUM_WORDS + 2)]; - wire [OPERAND_NUM_WORDS-1:0] fsm_shreg_store_dif_ab_n = fsm_shreg[FSM_SHREG_WIDTH - (0 * OPERAND_NUM_WORDS + 4) : FSM_SHREG_WIDTH - (1 * OPERAND_NUM_WORDS + 3)]; - wire [OPERAND_NUM_WORDS-1:0] fsm_shreg_store_data_d = fsm_shreg[FSM_SHREG_WIDTH - (1 * OPERAND_NUM_WORDS + 4) : FSM_SHREG_WIDTH - (2 * OPERAND_NUM_WORDS + 3)]; - wire [OPERAND_NUM_WORDS-1:0] fsm_shreg_inc_index_d = fsm_shreg[FSM_SHREG_WIDTH - (1 * OPERAND_NUM_WORDS + 5) : FSM_SHREG_WIDTH - (2 * OPERAND_NUM_WORDS + 4)]; - - wire fsm_latch_msb_borrow = fsm_shreg[FSM_SHREG_WIDTH - (1 * OPERAND_NUM_WORDS + 2)]; - - wire inc_index_ab = |fsm_shreg_inc_index_ab; - wire inc_index_n = |fsm_shreg_inc_index_n; - wire store_dif_ab = |fsm_shreg_store_dif_ab; - wire store_dif_ab_n = |fsm_shreg_store_dif_ab_n; - wire store_data_d = |fsm_shreg_store_data_d; - wire inc_index_d = |fsm_shreg_inc_index_d; - - always @(posedge clk or negedge rst_n) - // - if (rst_n == 1'b0) - // - fsm_shreg <= {{FSM_SHREG_WIDTH-1{1'b0}}, 1'b1}; - // - else begin - // - if (rdy) fsm_shreg <= {ena, {FSM_SHREG_WIDTH-2{1'b0}}, ~ena}; - // - else fsm_shreg <= {1'b0, fsm_shreg[FSM_SHREG_WIDTH-1:1]}; - // - end - - - // - // Borrow & Carry Masking Logic - // - reg sub32_b_mask; - reg add32_c_mask; - - - always @(posedge clk) begin - // - sub32_b_mask <= (index_ab == WORD_INDEX_ZERO) ? 1'b1 : 1'b0; - add32_c_mask <= (index_n == WORD_INDEX_ZERO) ? 1'b1 : 1'b0; - // - end - - assign sub32_b_in = sub32_b_out & ~sub32_b_mask; - assign add32_c_in = add32_c_out & ~add32_c_mask; - - - - // - // Borrow & Carry Latch Logic - // - reg sub32_borrow_latch; - - always @(posedge clk) begin - // - if (fsm_latch_msb_borrow) sub32_borrow_latch <= sub32_b_out; - // - end - - - // - // Intermediate Results - // - reg [32*OPERAND_NUM_WORDS-1:0] d_ab; - reg [32*OPERAND_NUM_WORDS-1:0] d_ab_n; - - always @(posedge clk) - // - if (store_data_d) begin - // - d_ab <= {{32{1'bX}}, d_ab[32*OPERAND_NUM_WORDS-1:32]}; - d_ab_n <= {{32{1'bX}}, d_ab_n[32*OPERAND_NUM_WORDS-1:32]}; - // - end else begin - // - if (store_dif_ab) d_ab <= {sub32_d, d_ab[32*OPERAND_NUM_WORDS-1:32]}; - if (store_dif_ab_n) d_ab_n <= {add32_s, d_ab_n[32*OPERAND_NUM_WORDS-1:32]}; - // - end - - - // - // Word Index Increment Logic - // - always @(posedge clk) - // - if (rdy) begin - // - index_ab <= WORD_INDEX_ZERO; - index_n <= WORD_INDEX_ZERO; - index_d <= WORD_INDEX_ZERO; - // - end else begin - // - if (inc_index_ab) index_ab <= WORD_INDEX_NEXT_OR_ZERO(index_ab); - if (inc_index_n) index_n <= WORD_INDEX_NEXT_OR_ZERO(index_n); - if (inc_index_d) index_d <= WORD_INDEX_NEXT_OR_ZERO(index_d); - // - end - - - // - // Output Sum Selector - // - wire mux_select_ab_n = sub32_borrow_latch; - - - // - // Output Data and Write Enable Logic - // - reg d_wren_reg; - reg [31: 0] d_dout_reg; - wire [31: 0] d_dout_mux = mux_select_ab_n ? d_ab_n[31:0] : d_ab[31:0]; - - assign d_wren = d_wren_reg; - assign d_dout = d_dout_reg; - - always @(posedge clk) - // - if (rdy) begin - // - d_wren_reg <= 1'b0; - d_dout_reg <= {32{1'bX}}; - // - end else begin - // - d_wren_reg <= store_data_d; - d_dout_reg <= store_data_d ? d_dout_mux : {32{1'bX}}; - // - end - - -endmodule - - -//------------------------------------------------------------------------------ -// End-of-File -//------------------------------------------------------------------------------ |