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[/] [rtf8088/] [trunk/] [rtl/] [verilog/] [FETCH_DATA.v] - Rev 8
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//============================================================================= // (C) 2009-2012 Robert Finch, Stratford // robfinch<remove>@opencores.org // // FETCH_DATA // Fetch data from memory. // // // This source file is free software: you can redistribute it and/or modify // it under the terms of the GNU Lesser General Public License as published // by the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // // This source file 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/>. // // //============================================================================= // FETCH_DATA: if (!cyc_o) begin cyc_type <= `CT_RDMEM; lock_o <= bus_locked | w; cyc_o <= 1'b1; stb_o <= 1'b1; we_o <= 1'b0; adr_o <= ea; end else if (ack_i) begin cyc_type <= `CT_PASSIVE; cyc_o <= w; stb_o <= 1'b0; if (d) begin a <= rrro; b[ 7:0] <= dat_i; b[15:8] <= {8{dat_i[7]}}; end else begin b <= rrro; a[ 7:0] <= dat_i; a[15:8] <= {8{dat_i[7]}}; end if (w) state <= FETCH_DATA1; else begin case(ir) 8'h80: state <= FETCH_IMM8; 8'h81: state <= FETCH_IMM16; 8'h83: state <= FETCH_IMM8; 8'hC0: state <= FETCH_IMM8; 8'hC1: state <= FETCH_IMM8; 8'hC6: state <= FETCH_IMM8; 8'hC7: state <= FETCH_IMM16; 8'hF6: state <= FETCH_IMM8; 8'hF7: state <= FETCH_IMM16; default: state <= EXECUTE; endcase hasFetchedData <= 1'b1; end end FETCH_DATA1: if (!stb_o) begin cyc_type <= `CT_RDMEM; lock_o <= bus_locked | w; stb_o <= 1'b1; adr_o <= ea_inc; end else if (ack_i) begin cyc_type <= `CT_PASSIVE; lock_o <= bus_locked; cyc_o <= 1'b0; stb_o <= 1'b0; if (d) b[15:8] <= dat_i; else a[15:8] <= dat_i; case(ir) 8'h80: state <= FETCH_IMM8; 8'h81: state <= FETCH_IMM16; 8'h83: state <= FETCH_IMM8; 8'hC0: state <= FETCH_IMM8; 8'hC1: state <= FETCH_IMM8; 8'hC6: state <= FETCH_IMM8; 8'hC7: state <= FETCH_IMM16; 8'hF6: state <= FETCH_IMM8; 8'hF7: state <= FETCH_IMM16; default: state <= EXECUTE; endcase hasFetchedData <= 1'b1; end
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