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// ============================================================================
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// ============================================================================
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// ALU
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// ALU
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// - perform datapath operations
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// - perform datapath operations
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//
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//
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//
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//
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// (C) 2009-2012 Robert Finch
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// (C) 2009-2013 Robert Finch
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// robfinch[remove]@opencores.org
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// robfinch[remove]@finitron.ca
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//
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//
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//
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//
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// This source file is free software: you can redistribute it and/or modify
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// This source file is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published
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// it under the terms of the GNU Lesser General Public License as published
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// by the Free Software Foundation, either version 3 of the License, or
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// by the Free Software Foundation, either version 3 of the License, or
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.divByZero(),
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.divByZero(),
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.done(div32_done)
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.done(div32_done)
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);
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);
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always @(ir or ir2 or a or b or cf or af or al or ah or aldv10 or TTT)
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always @* //(ir or ir2 or a or b or cf or af or al or ah or aldv10 or TTT)
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begin
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begin
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casex(ir)
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casex(ir)
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`MOV_M2AL,`MOV_M2AX,`LDS,`LES:
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`MOV_M2AL,`MOV_M2AX,`LDS,`LES:
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alu_o <= a;
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alu_o <= a;
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`MOV_MR,`MOV_R2S,
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`MOV_MR,`MOV_R2S,
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`XOR,`XOR_ALI8,`XOR_AXI16: alu_o <= a ^ b;
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`XOR,`XOR_ALI8,`XOR_AXI16: alu_o <= a ^ b;
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`CMP,`CMP_ALI8,`CMP_AXI16: alu_o <= a - b;
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`CMP,`CMP_ALI8,`CMP_AXI16: alu_o <= a - b;
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`SCASB,`SCASW,`CMPSB,`CMPSW: alu_o <= a - b;
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`SCASB,`SCASW,`CMPSB,`CMPSW: alu_o <= a - b;
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`INC_REG: alu_o <= a + 16'd1;
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`INC_REG: alu_o <= a + 16'd1;
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`DEC_REG: alu_o <= a - 16'd1;
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`DEC_REG: alu_o <= a - 16'd1;
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`IMUL: alu_o <= w ? p : wp[15:0];
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// `IMUL: alu_o <= w ? p : wp[15:0];
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`ALU_I2R8:
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`ALU_I2R8:
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case(TTT)
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case(TTT)
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3'd0: alu_o <= a + b; // ADD
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3'd0: alu_o <= a + b; // ADD
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3'd1: alu_o <= a | b; // OR
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3'd1: alu_o <= a | b; // OR
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3'd2: alu_o <= a + b + cf; // ADC
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3'd2: alu_o <= a + b + cf; // ADC
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3'd5: alu_o <= a - b; // SUB
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3'd5: alu_o <= a - b; // SUB
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3'd6: alu_o <= a ^ b; // XOR
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3'd6: alu_o <= a ^ b; // XOR
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default: alu_o <= 16'h0000;
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default: alu_o <= 16'h0000;
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endcase
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endcase
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8'hF6,8'hF7:
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8'hF6,8'hF7:
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begin
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case(TTT)
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case(TTT)
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3'd0: alu_o <= a & b; // TEST
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3'd0: alu_o <= a & b; // TEST
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3'd2: alu_o <= ~b; // NOT
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3'd2: alu_o <= ~b; // NOT
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3'd3: alu_o <= -b; // NEG
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3'd3: alu_o <= -b; // NEG
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3'd4: alu_o <= w ? p32[15:0] : p16; // MUL
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3'd4: alu_o <= w ? p32[15:0] : p16; // MUL
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3'd5: alu_o <= w ? wp[15:0] : p[15:0]; // IMUL
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3'd5: alu_o <= w ? wp[15:0] : p[15:0]; // IMUL
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3'd6: alu_o <= 16'h0000; // DIV
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3'd6: alu_o <= 16'h0000; // DIV
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3'd7: alu_o <= 16'h0000; // IDIV
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3'd7: alu_o <= 16'h0000; // IDIV
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default: alu_o <= 16'h0000;
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default: alu_o <= 16'h0000;
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endcase
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endcase
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end
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`AAA:
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`AAA:
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if (al[3:0]>4'h9 || af) begin
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if (al[3:0]>4'h9 || af) begin
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alu_o[3:0] <= al[3:0] + 4'd6;
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alu_o[3:0] <= al[3:0] + 4'd6;
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alu_o[7:4] <= 4'h0;
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alu_o[7:4] <= 4'h0;
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alu_o[15:8] <= ah + 8'd1;
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alu_o[15:8] <= ah + 8'd1;
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