core/insn_alu_a.v

   1 `define INSN_alu_RLCA           3'b000
   2 `define INSN_alu_RRCA           3'b001
   3 `define INSN_alu_RLA            3'b010
   4 `define INSN_alu_RRA            3'b011
   5 `define INSN_alu_DAA            3'b100
   6 `define INSN_alu_CPL            3'b101
   7 `define INSN_alu_SCF            3'b110
   8 `define INSN_alu_CCF            3'b111
   9
  10 `define INSN_ALU_A              9'b000xxx111
  11
  12 `ifdef LOCALWIRES
  13         /* Y U Q */
  14         /* Derived from MESS opc_main.h */
  15         wire [8:0] daa_tmp_n0_h = ((`_F & `FLAG_H) || (`_A[3:0] > 9)) ? {1'b0,`_A} + 9'h06 : {1'b0,`_A};
  16         wire [8:0] daa_tmp_n0 = ((`_F & `FLAG_C) || (daa_tmp_n0_h[8:4] > 9)) ? daa_tmp_n0_h + 9'h60 : daa_tmp_n0_h;
  17
  18         wire [8:0] daa_tmp_n_h1 = (`_F & `FLAG_H) ? ({1'b0,`_A} - 9'h06) : {1'b0,`_A};
  19         wire [8:0] daa_tmp_n_h2 = ((`_F & `FLAG_H) && !(`_F & `FLAG_C)) ? {1'b0,daa_tmp_n_h1[7:0]} : daa_tmp_n_h1;
  20         wire [8:0] daa_tmp_n = (`_F & `FLAG_C) ? (daa_tmp_n_h2 - 9'h60) : daa_tmp_n_h2;
  21         wire [8:0] daa_tmp = (`_F & `FLAG_N) ? daa_tmp_n : daa_tmp_n0;
  22 `endif
  23
  24 `ifdef EXECUTE
  25         `INSN_ALU_A: begin
  26                 `EXEC_NEWCYCLE
  27                 `EXEC_INC_PC
  28         end
  29 `endif
  30
  31 `ifdef WRITEBACK
  32         `INSN_ALU_A: begin
  33                 case(opcode[5:3])
  34                 `INSN_alu_RLCA: begin
  35                         `_A <= {`_A[6:0],`_A[7]};
  36                         `_F <= {`_F[7:5],`_A[7],`_F[3:0]};
  37                 end
  38                 `INSN_alu_RRCA: begin
  39                         `_A <= {`_A[0],`_A[7:1]};
  40                         `_F <= {`_F[7:5],`_A[0],`_F[3:0]};
  41                 end
  42                 `INSN_alu_RLA: begin
  43                         `_A <= {`_A[6:0],`_F[4]};
  44                         `_F <= {`_F[7:5],`_A[7],`_F[3:0]};
  45                 end
  46                 `INSN_alu_RRA: begin
  47                         `_A <= {`_F[4],`_A[7:1]};
  48                         `_F <= {`_F[7:5],`_A[0],`_F[3:0]};
  49                 end
  50                 `INSN_alu_DAA: begin
  51                         `_A <= daa_tmp[7:0];
  52                         `_F <= {
  53                                         (daa_tmp[7:0] == 0) ? 1'b1 : 8'b0, /* Z */
  54                                         2'b00, /* NH */
  55                                         daa_tmp[8], /* C */
  56                                         `_F[3:0]
  57                                 };
  58                 end
  59                 `INSN_alu_CPL: begin
  60                         `_A <= ~`_A;
  61                         `_F <= {`_F[7],1'b1,1'b1,`_F[4:0]};
  62                 end
  63                 `INSN_alu_SCF: begin
  64                         `_F <= {`_F[7],3'b001,`_F[3:0]};
  65                 end
  66                 `INSN_alu_CCF: begin
  67                         `_F <= {`_F[7],2'b00,~`_F[4],`_F[3:0]};
  68                 end
  69                 endcase
  70         end
  71 `endif