2 use IEEE.std_logic_1164.all;
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3 use IEEE.numeric_std.all;
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5 use work.alu_pkg.all;
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8 architecture behaviour of alu is
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14 reset : in std_logic;
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16 left_operand : in gp_register_t;
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17 right_operand : in gp_register_t;
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18 op_detail : in op_opt_t;
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19 alu_state : in alu_result_rec;
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20 alu_result : out alu_result_rec
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22 end component exec_op;
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24 signal add_result, and_result, or_result, xor_result, shift_result : alu_result_rec;
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28 add_inst : entity work.exec_op(add_op)
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29 port map(clk,reset,left_operand, right_operand, op_detail, alu_state, add_result);
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31 and_inst : entity work.exec_op(and_op)
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32 port map(clk,reset,left_operand, right_operand, op_detail, alu_state, and_result);
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34 or_inst : entity work.exec_op(or_op)
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35 port map(clk,reset,left_operand, right_operand, op_detail, alu_state, or_result);
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37 xor_inst : entity work.exec_op(xor_op)
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38 port map(clk,reset,left_operand, right_operand, op_detail, alu_state, xor_result);
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40 shift_inst : entity work.exec_op(shift_op)
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41 port map(clk,reset,left_operand, right_operand, op_detail, alu_state, shift_result);
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43 calc: process(left_operand, right_operand, cond, op_group, op_detail ,alu_state,and_result,add_result,or_result,xor_result,shift_result)
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44 variable result_v : alu_result_rec;
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45 variable res_prod : std_logic;
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46 variable cond_met : std_logic;
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47 variable mem_en : std_logic;
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49 result_v := alu_state;
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51 result_v.result := add_result.result;
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54 addr <= add_result.result;
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58 cond_met := not(alu_state.status.zero);
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60 cond_met := alu_state.status.zero;
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62 cond_met := not(alu_state.status.oflo);
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64 cond_met := alu_state.status.oflo;
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66 cond_met := not(alu_state.status.carry);
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68 cond_met := alu_state.status.carry;
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70 cond_met := not(alu_state.status.sign);
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72 cond_met := alu_state.status.sign;
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74 cond_met := not(alu_state.status.carry) and not(alu_state.status.zero);
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76 cond_met := alu_state.status.carry or alu_state.status.zero;
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78 cond_met := not(alu_state.status.sign xor alu_state.status.oflo);
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80 cond_met := alu_state.status.sign xor alu_state.status.oflo;
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82 cond_met := not(alu_state.status.zero) and not(alu_state.status.sign xor alu_state.status.oflo);
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84 cond_met := alu_state.status.zero or (alu_state.status.sign xor alu_state.status.oflo);
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89 when others => null;
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94 result_v := add_result;
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96 result_v := and_result;
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98 result_v := or_result;
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100 result_v := xor_result;
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102 result_v := shift_result;
104 if op_detail(IMM_OPT) = '1' then
105 result_v := right_operand;
110 result_v.status.zero := '0';
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111 if result_v.result = REG_ZERO then
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112 result_v.status.zero := '1';
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115 result_v.status.sign := result_v.result(gp_register_t'high);
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117 if (op_detail(NO_PSW_OPT) = '1') or (cond_met = '0') then
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118 result_v.status := alu_state.status;
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121 result_v.reg_op := not(op_detail(NO_DST_OPT)) and res_prod and cond_met;
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122 result_v.mem_en := mem_en and cond_met;
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125 data <= add_result.result;
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126 alu_result <= result_v;
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130 end architecture behaviour;
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