New generation makefile. Code that will reliably break the machine.

[fpgaboy.git] / GBZ80Core.v

diff --git a/GBZ80Core.v b/GBZ80Core.v
index b7994ae3ce4fea35f6d54ed170c8385bdf8d4e59..f4383397978f92fd5539f45dd90b7c40ee1415fd 100644 (file)
--- a/GBZ80Core.v
+++ b/GBZ80Core.v
@@ -1,37 +1,78 @@
-`define REG_A 0
-`define REG_B 1
-`define REG_C 2
-`define REG_D 3
-`define REG_E 4
-`define REG_F 5
-`define REG_H 6
-`define REG_L 7
-`define REG_SPH 8
-`define REG_SPL 9
-`define REG_PCH 10
-`define REG_PCL 11
+`define REG_A  0
+`define REG_B  1
+`define REG_C  2
+`define REG_D  3
+`define REG_E  4
+`define REG_F  5
+`define REG_H  6
+`define REG_L  7
+`define REG_SPH        8
+`define REG_SPL        9
+`define REG_PCH        10
+`define REG_PCL        11

 
 

-`define FLAG_Z 8'b10000000
-`define FLAG_N 8'b01000000
-`define FLAG_H 8'b00100000
-`define FLAG_C 8'b00010000
+`define _A     registers[`REG_A]
+`define _B     registers[`REG_B]
+`define _C     registers[`REG_C]
+`define _D     registers[`REG_D]
+`define _E     registers[`REG_E]
+`define _F     registers[`REG_F]
+`define _H     registers[`REG_H]
+`define _L     registers[`REG_L]
+`define _SPH   registers[`REG_SPH]
+`define _SPL   registers[`REG_SPL]
+`define _PCH   registers[`REG_PCH]
+`define _PCL   registers[`REG_PCL]
+`define _AF    {`_A, `_F}
+`define _BC    {`_B, `_C}
+`define _DE    {`_D, `_E}
+`define _HL    {`_H, `_L}
+`define _SP    {`_SPH, `_SPL}
+`define _PC    {`_PCH, `_PCL}

 
 

-`define STATE_FETCH                    2'h0
-`define STATE_DECODE                   2'h1
+`define FLAG_Z 8'b10000000
+`define FLAG_N 8'b01000000
+`define FLAG_H 8'b00100000
+`define FLAG_C 8'b00010000
+
+`define STATE_FETCH            2'h0
+`define STATE_DECODE           2'h1

 `define STATE_EXECUTE          2'h2
 `define STATE_WRITEBACK                2'h3
 
 `define INSN_LD_reg_imm8       8'b00xxx110
 `define STATE_EXECUTE          2'h2
 `define STATE_WRITEBACK                2'h3
 
 `define INSN_LD_reg_imm8       8'b00xxx110

-`define INSN_HALT                              8'b01110110
+`define INSN_HALT              8'b01110110

 `define INSN_LD_HL_reg         8'b01110xxx
 `define INSN_LD_reg_HL         8'b01xxx110
 `define INSN_LD_reg_reg                8'b01xxxxxx
 `define INSN_LD_reg_imm16      8'b00xx0001
 `define INSN_LD_SP_HL          8'b11111001
 `define INSN_PUSH_reg          8'b11xx0101
 `define INSN_LD_HL_reg         8'b01110xxx
 `define INSN_LD_reg_HL         8'b01xxx110
 `define INSN_LD_reg_reg                8'b01xxxxxx
 `define INSN_LD_reg_imm16      8'b00xx0001
 `define INSN_LD_SP_HL          8'b11111001
 `define INSN_PUSH_reg          8'b11xx0101

-`define INSN_POP_reg                   8'b11xx0001
-`define INSN_LDH_AC                    8'b111x0010     // Either LDH A,(C) or LDH (C),A
-`define INSN_LDx_AHL                   8'b001xx010     // LDD/LDI A,(HL) / (HL),A
+`define INSN_POP_reg           8'b11xx0001
+`define INSN_LDH_AC            8'b111x0010     // Either LDH A,(C) or LDH (C),A
+`define INSN_LDx_AHL           8'b001xx010     // LDD/LDI A,(HL) / (HL),A
+`define INSN_ALU8              8'b10xxxxxx     // 10 xxx yyy
+`define INSN_NOP               8'b00000000
+`define INSN_RST               8'b11xxx111
+`define INSN_RET               8'b110x1001     // 1 = RETI, 0 = RET
+`define INSN_RETCC             8'b110xx000
+`define INSN_CALL              8'b11001101
+`define INSN_CALLCC            8'b110xx100     // Not that call/cc.
+`define INSN_JP_imm            8'b11000011
+`define INSN_JPCC_imm          8'b110xx010
+`define INSN_ALU_A             8'b00xxx111
+`define INSN_JP_HL             8'b11101001
+`define INSN_JR_imm            8'b00011000
+`define INSN_JRCC_imm          8'b001xx000
+`define INSN_INCDEC16          8'b00xxx011
+`define INSN_VOP_INTR          8'b11111100     // 0xFC is grabbed by the fetch if there is an interrupt pending.
+`define INSN_DI                        8'b11110011
+`define INSN_EI                        8'b11111011
+
+`define INSN_cc_NZ             2'b00
+`define INSN_cc_Z              2'b01
+`define INSN_cc_NC             2'b10
+`define INSN_cc_C              2'b11

 
 `define INSN_reg_A             3'b111
 `define INSN_reg_B             3'b000
 
 `define INSN_reg_A             3'b111
 `define INSN_reg_B             3'b000


@@ -40,23 +81,47 @@
 `define INSN_reg_E             3'b011
 `define INSN_reg_H             3'b100
 `define INSN_reg_L             3'b101
 `define INSN_reg_E             3'b011
 `define INSN_reg_H             3'b100
 `define INSN_reg_L             3'b101

-`define INSN_reg_dHL   3'b110
-`define INSN_reg16_BC  2'b00
-`define INSN_reg16_DE  2'b01
-`define INSN_reg16_HL  2'b10
-`define INSN_reg16_SP  2'b11
-`define INSN_stack_AF  2'b11
-`define INSN_stack_BC  2'b00
-`define INSN_stack_DE  2'b01
-`define INSN_stack_HL  2'b10
+`define INSN_reg_dHL           3'b110
+`define INSN_reg16_BC          2'b00
+`define INSN_reg16_DE          2'b01
+`define INSN_reg16_HL          2'b10
+`define INSN_reg16_SP          2'b11
+`define INSN_stack_AF          2'b11
+`define INSN_stack_BC          2'b00
+`define INSN_stack_DE          2'b01
+`define INSN_stack_HL          2'b10
+`define INSN_alu_ADD           3'b000
+`define INSN_alu_ADC           3'b001
+`define INSN_alu_SUB           3'b010
+`define INSN_alu_SBC           3'b011
+`define INSN_alu_AND           3'b100
+`define INSN_alu_XOR           3'b101
+`define INSN_alu_OR            3'b110
+`define INSN_alu_CP            3'b111          // Oh lawd, is dat some CP?
+`define INSN_alu_RLCA          3'b000
+`define INSN_alu_RRCA          3'b001
+`define INSN_alu_RLA           3'b010
+`define INSN_alu_RRA           3'b011
+`define INSN_alu_DAA           3'b100
+`define INSN_alu_CPL           3'b101
+`define INSN_alu_SCF           3'b110
+`define INSN_alu_CCF           3'b111
+
+`define EXEC_INC_PC            `_PC <= `_PC + 1;
+`define EXEC_NEXTADDR_PCINC    address <= `_PC + 1;
+`define EXEC_NEWCYCLE          begin newcycle <= 1; rd <= 1; wr <= 0; end
+`define EXEC_WRITE(ad, da)     begin address <= (ad); wdata <= (da); wr <= 1; end end
+`define EXEC_READ(ad)          begin address <= (ad); rd <= 1; end end
+

 module GBZ80Core(
        input clk,
        output reg [15:0] busaddress,   /* BUS_* is latched on STATE_FETCH. */
        inout [7:0] busdata,
 module GBZ80Core(
        input clk,
        output reg [15:0] busaddress,   /* BUS_* is latched on STATE_FETCH. */
        inout [7:0] busdata,

-       output reg buswr, output reg busrd);
+       output reg buswr, output reg busrd,
+       input irq, input [7:0] jaddr);

        
        

-       reg [1:0] state = 0;                                    /* State within this bus cycle (see STATE_*). */
-       reg [2:0] cycle = 0;                                    /* Cycle for instructions. */
+       reg [1:0] state;                                        /* State within this bus cycle (see STATE_*). */
+       reg [2:0] cycle;                                        /* Cycle for instructions. */

        
        reg [7:0] registers[11:0];
        
        
        reg [7:0] registers[11:0];
        


@@ -65,13 +130,15 @@ module GBZ80Core(
        reg [7:0] opcode;                               /* Opcode from the current machine cycle. */
        
        reg [7:0] rdata, wdata;         /* Read data from this bus cycle, or write data for the next. */
        reg [7:0] opcode;                               /* Opcode from the current machine cycle. */
        
        reg [7:0] rdata, wdata;         /* Read data from this bus cycle, or write data for the next. */

-       reg rd = 1, wr = 0, newcycle = 1;
+       reg rd, wr, newcycle;

        
        

-       reg [7:0] tmp;                                  /* Generic temporary reg. */
+       reg [7:0] tmp, tmp2;                    /* Generic temporary regs. */

        
        reg [7:0] buswdata;
        assign busdata = buswr ? buswdata : 8'bzzzzzzzz;
        
        
        reg [7:0] buswdata;
        assign busdata = buswr ? buswdata : 8'bzzzzzzzz;
        

+       reg ie, iedelay;
+       

        initial begin
                registers[ 0] <= 0;
                registers[ 1] <= 0;
        initial begin
                registers[ 0] <= 0;
                registers[ 1] <= 0;


@@ -85,29 +152,54 @@ module GBZ80Core(
                registers[ 9] <= 0;
                registers[10] <= 0;
                registers[11] <= 0;
                registers[ 9] <= 0;
                registers[10] <= 0;
                registers[11] <= 0;

+               rd <= 1;
+               wr <= 0;
+               newcycle <= 1;
+               state <= 0;
+               cycle <= 0;
+               busrd <= 0;
+               buswr <= 0;
+               busaddress <= 0;
+               ie <= 0;
+               iedelay <= 0;
+               opcode <= 0;
+               state <= `STATE_WRITEBACK;
+               cycle <= 0;

        end
 
        always @(posedge clk)
                case (state)
                `STATE_FETCH: begin
        end
 
        always @(posedge clk)
                case (state)
                `STATE_FETCH: begin

-                       if (wr)
-                               buswdata <= wdata;
-                       if (newcycle)
+                       if (newcycle) begin

                                busaddress <= {registers[`REG_PCH], registers[`REG_PCL]};
                                busaddress <= {registers[`REG_PCH], registers[`REG_PCL]};

-                       else
+                               buswr <= 0;
+                               busrd <= 1;
+                       end else begin

                                busaddress <= address;
                                busaddress <= address;

-                       buswr <= wr;
-                       busrd <= rd;
+                               buswr <= wr;
+                               busrd <= rd;
+                               if (wr)
+                                       buswdata <= wdata;
+                       end

                        state <= `STATE_DECODE;
                end
                `STATE_DECODE: begin
                        if (newcycle) begin
                        state <= `STATE_DECODE;
                end
                `STATE_DECODE: begin
                        if (newcycle) begin

-                               opcode <= busdata;
+                               if (ie && irq)
+                                       opcode <= `INSN_VOP_INTR;
+                               else
+                                       opcode <= busdata;

                                rdata <= busdata;
                                newcycle <= 0;
                                cycle <= 0;
                                rdata <= busdata;
                                newcycle <= 0;
                                cycle <= 0;

-                       end else
+                       end else begin

                                if (rd) rdata <= busdata;
                                if (rd) rdata <= busdata;

+                               cycle <= cycle + 1;
+                       end
+                       if (iedelay) begin
+                               ie <= 1;
+                               iedelay <= 0;
+                       end

                        buswr <= 0;
                        busrd <= 0;
                        wr <= 0;
                        buswr <= 0;
                        busrd <= 0;
                        wr <= 0;


@@ -117,192 +209,10 @@ module GBZ80Core(
                        state <= `STATE_EXECUTE;
                end
                `STATE_EXECUTE: begin
                        state <= `STATE_EXECUTE;
                end
                `STATE_EXECUTE: begin

-`define EXEC_INC_PC \
-       {registers[`REG_PCH], registers[`REG_PCL]} <= {registers[`REG_PCH], registers[`REG_PCL]} + 1
-`define EXEC_NEXTADDR_PCINC \
-       address <= {registers[`REG_PCH], registers[`REG_PCL]} + 1
-`define EXEC_NEWCYCLE \
-       newcycle <= 1; rd <= 1; wr <= 0

                        casex (opcode)
                        casex (opcode)

-                       `INSN_LD_reg_imm8: begin
-                               case (cycle)
-                               0:      begin
-                                               `EXEC_INC_PC;
-                                               `EXEC_NEXTADDR_PCINC;
-                                               rd <= 1;
-                                       end
-                               1: begin
-                                               `EXEC_INC_PC;
-                                               if (opcode[5:3] == `INSN_reg_dHL) begin
-                                                       address <= {registers[`REG_H], registers[`REG_L]};
-                                                       wdata <= rdata;
-                                                       rd <= 0;
-                                                       wr <= 1;
-                                               end else begin
-                                                       `EXEC_NEWCYCLE;
-                                               end
-                                       end
-                               2: begin
-                                               `EXEC_NEWCYCLE;
-                                       end
-                               endcase
-                       end
-                       `INSN_HALT: begin
-                               `EXEC_NEWCYCLE;
-                               /* XXX Interrupts needed for HALT. */
-                       end
-                       `INSN_LD_HL_reg: begin
-                               case (cycle)
-                               0:      begin
-                                               case (opcode[2:0])
-                                               `INSN_reg_A:    begin wdata <= registers[`REG_A]; end
-                                               `INSN_reg_B:    begin wdata <= registers[`REG_B]; end
-                                               `INSN_reg_C:    begin wdata <= registers[`REG_C]; end
-                                               `INSN_reg_D:    begin wdata <= registers[`REG_D]; end
-                                               `INSN_reg_E:    begin wdata <= registers[`REG_E]; end
-                                               `INSN_reg_H:    begin wdata <= registers[`REG_H]; end
-                                               `INSN_reg_L:    begin wdata <= registers[`REG_L]; end
-                                               endcase
-                                               address <= {registers[`REG_H], registers[`REG_L]};
-                                               wr <= 1; rd <= 0;
-                                       end
-                               1:      begin
-                                               `EXEC_INC_PC;
-                                               `EXEC_NEWCYCLE;
-                                       end
-                               endcase
-                       end
-                       `INSN_LD_reg_HL: begin
-                               case(cycle)
-                               0: begin
-                                               address <= {registers[`REG_H], registers[`REG_L]};
-                                               rd <= 1;
-                                       end
-                               1: begin
-                                               tmp <= rdata;
-                                               `EXEC_INC_PC;
-                                               `EXEC_NEWCYCLE;
-                                       end
-                               endcase
-                       end
-                       `INSN_LD_reg_reg: begin
-                               `EXEC_INC_PC;
-                               `EXEC_NEWCYCLE;
-                               case (opcode[2:0])
-                               `INSN_reg_A:    begin tmp <= registers[`REG_A]; end
-                               `INSN_reg_B:    begin tmp <= registers[`REG_B]; end
-                               `INSN_reg_C:    begin tmp <= registers[`REG_C]; end
-                               `INSN_reg_D:    begin tmp <= registers[`REG_D]; end
-                               `INSN_reg_E:    begin tmp <= registers[`REG_E]; end
-                               `INSN_reg_H:    begin tmp <= registers[`REG_H]; end
-                               `INSN_reg_L:    begin tmp <= registers[`REG_L]; end
-                               endcase
-                       end
-                       `INSN_LD_reg_imm16: begin
-                               `EXEC_INC_PC;
-                               case (cycle)
-                               0:      begin
-                                               `EXEC_NEXTADDR_PCINC;
-                                               rd <= 1;
-                                       end
-                               1:      begin
-                                               `EXEC_NEXTADDR_PCINC;
-                                               rd <= 1;
-                                       end
-                               2: begin `EXEC_NEWCYCLE; end
-                               endcase
-                       end
-                       `INSN_LD_SP_HL: begin
-                               case (cycle)
-                               0:      begin
-                                               tmp <= registers[`REG_H];
-                                       end
-                               1:      begin
-                                               `EXEC_NEWCYCLE;
-                                               `EXEC_INC_PC;
-                                               tmp <= registers[`REG_L];
-                                       end
-                               endcase
-                       end
-                       `INSN_PUSH_reg: begin   /* PUSH is 16 cycles! */
-                               case (cycle)
-                               0: begin
-                                               wr <= 1;
-                                               address <= {registers[`REG_SPH],registers[`REG_SPL]}-1;
-                                               case (opcode[5:4])
-                                               `INSN_stack_AF: wdata <= registers[`REG_A];
-                                               `INSN_stack_BC: wdata <= registers[`REG_B];
-                                               `INSN_stack_DE: wdata <= registers[`REG_D];
-                                               `INSN_stack_HL: wdata <= registers[`REG_H];
-                                               endcase
-                                       end
-                               1: begin
-                                               wr <= 1;
-                                               address <= {registers[`REG_SPH],registers[`REG_SPL]}-1;
-                                               case (opcode[5:4])
-                                               `INSN_stack_AF: wdata <= registers[`REG_F];
-                                               `INSN_stack_BC: wdata <= registers[`REG_C];
-                                               `INSN_stack_DE: wdata <= registers[`REG_E];
-                                               `INSN_stack_HL: wdata <= registers[`REG_L];
-                                               endcase
-                                       end
-                               2:      begin /* TWIDDLE OUR FUCKING THUMBS! */ end
-                               3: begin
-                                               `EXEC_NEWCYCLE;
-                                               `EXEC_INC_PC;
-                                       end
-                               endcase
-                       end
-                       `INSN_POP_reg: begin    /* POP is 12 cycles! */
-                               case (cycle)
-                               0: begin
-                                               rd <= 1;
-                                               address <= {registers[`REG_SPH],registers[`REG_SPL]};
-                                       end
-                               1: begin
-                                               rd <= 1;
-                                               address <= {registers[`REG_SPH],registers[`REG_SPL]};
-                                       end
-                               2: begin
-                                               `EXEC_NEWCYCLE;
-                                               `EXEC_INC_PC;
-                                       end
-                               endcase
-                       end
-                       `INSN_LDH_AC: begin
-                               case (cycle)
-                               0:      begin
-                                               address <= {8'hFF,registers[`REG_C]};
-                                               if (opcode[4]) begin    // LD A,(C)
-                                                       rd <= 1;
-                                               end else begin
-                                                       wr <= 1;
-                                                       wdata <= registers[`REG_A];
-                                               end
-                                       end
-                               1: begin
-                                               `EXEC_NEWCYCLE;
-                                               `EXEC_INC_PC;
-                                       end
-                               endcase
-                       end
-                       `INSN_LDx_AHL: begin
-                               case (cycle)
-                               0: begin
-                                               address <= {registers[`REG_H],registers[`REG_L]};
-                                               if (opcode[3]) begin    // LDx A, (HL)
-                                                       rd <= 1;
-                                               end else begin
-                                                       wr <= 1;
-                                                       wdata <= registers[`REG_A];
-                                               end
-                                       end
-                               1:      begin
-                                               `EXEC_NEWCYCLE;
-                                               `EXEC_INC_PC;
-                                       end
-                               endcase
-                       end
+                       `define EXECUTE
+                       `include "allinsns.v"
+                       `undef EXECUTE

                        default:
                                $stop;
                        endcase
                        default:
                                $stop;
                        endcase


@@ -310,184 +220,13 @@ module GBZ80Core(
                end
                `STATE_WRITEBACK: begin
                        casex (opcode)
                end
                `STATE_WRITEBACK: begin
                        casex (opcode)

-                       `INSN_LD_reg_imm8:
-                               case (cycle)
-                               0: cycle <= 1;
-                               1: case (opcode[5:3])
-                                       `INSN_reg_A:    begin registers[`REG_A] <= rdata; cycle <= 0; end
-                                       `INSN_reg_B:    begin registers[`REG_B] <= rdata; cycle <= 0; end
-                                       `INSN_reg_C:    begin registers[`REG_C] <= rdata; cycle <= 0; end
-                                       `INSN_reg_D:    begin registers[`REG_D] <= rdata; cycle <= 0; end
-                                       `INSN_reg_E:    begin registers[`REG_E] <= rdata; cycle <= 0; end
-                                       `INSN_reg_H:    begin registers[`REG_H] <= rdata; cycle <= 0; end
-                                       `INSN_reg_L:    begin registers[`REG_L] <= rdata; cycle <= 0; end
-                                       `INSN_reg_dHL:  cycle <= 2;
-                                       endcase
-                               2: cycle <= 0;
-                               endcase
-                       `INSN_HALT: begin
-                               /* Nothing needs happen here. */
-                               /* XXX Interrupts needed for HALT. */
-                       end
-                       `INSN_LD_HL_reg: begin
-                               case (cycle)
-                               0: cycle <= 1;
-                               1: cycle <= 0;
-                               endcase
-                       end
-                       `INSN_LD_reg_HL: begin
-                               case (cycle)
-                               0:      cycle <= 1;
-                               1:      begin
-                                               case (opcode[5:3])
-                                               `INSN_reg_A:    begin registers[`REG_A] <= tmp; end
-                                               `INSN_reg_B:    begin registers[`REG_B] <= tmp; end
-                                               `INSN_reg_C:    begin registers[`REG_C] <= tmp; end
-                                               `INSN_reg_D:    begin registers[`REG_D] <= tmp; end
-                                               `INSN_reg_E:    begin registers[`REG_E] <= tmp; end
-                                               `INSN_reg_H:    begin registers[`REG_H] <= tmp; end
-                                               `INSN_reg_L:    begin registers[`REG_L] <= tmp; end
-                                               endcase
-                                               cycle <= 0;
-                                       end
-                               endcase
-                       end
-                       `INSN_LD_reg_reg: begin
-                               case (opcode[5:3])
-                               `INSN_reg_A:    begin registers[`REG_A] <= tmp; end
-                               `INSN_reg_B:    begin registers[`REG_B] <= tmp; end
-                               `INSN_reg_C:    begin registers[`REG_C] <= tmp; end
-                               `INSN_reg_D:    begin registers[`REG_D] <= tmp; end
-                               `INSN_reg_E:    begin registers[`REG_E] <= tmp; end
-                               `INSN_reg_H:    begin registers[`REG_H] <= tmp; end
-                               `INSN_reg_L:    begin registers[`REG_L] <= tmp; end
-                               endcase
-                       end
-                       `INSN_LD_reg_imm16: begin
-                               case (cycle)
-                               0:      cycle <= 1;
-                               1:      begin
-                                               case (opcode[5:4])
-                                               `INSN_reg16_BC: registers[`REG_C] <= rdata;
-                                               `INSN_reg16_DE: registers[`REG_E] <= rdata;
-                                               `INSN_reg16_HL: registers[`REG_L] <= rdata;
-                                               `INSN_reg16_SP: registers[`REG_SPL] <= rdata;
-                                               endcase
-                                               cycle <= 2;
-                                       end
-                               2: begin
-                                               case (opcode[5:4])
-                                               `INSN_reg16_BC: registers[`REG_B] <= rdata;
-                                               `INSN_reg16_DE: registers[`REG_D] <= rdata;
-                                               `INSN_reg16_HL: registers[`REG_H] <= rdata;
-                                               `INSN_reg16_SP: registers[`REG_SPH] <= rdata;
-                                               endcase
-                                               cycle <= 0;
-                                       end
-                               endcase
-                       end
-                       `INSN_LD_SP_HL: begin
-                               case (cycle)
-                               0: begin
-                                               cycle <= 1;
-                                               registers[`REG_SPH] <= tmp;
-                                       end
-                               1: begin
-                                               cycle <= 0;
-                                               registers[`REG_SPL] <= tmp;
-                                       end
-                               endcase
-                       end
-                       `INSN_PUSH_reg: begin   /* PUSH is 16 cycles! */
-                               case (cycle)
-                               0: begin
-                                               {registers[`REG_SPH],registers[`REG_SPL]} <=
-                                                       {registers[`REG_SPH],registers[`REG_SPL]} - 1;
-                                               cycle <= 1;
-                                       end
-                               1:      begin
-                                               {registers[`REG_SPH],registers[`REG_SPL]} <=
-                                                       {registers[`REG_SPH],registers[`REG_SPL]} - 1;
-                                               cycle <= 2;
-                                       end
-                               2:      cycle <= 3;
-                               3:      cycle <= 0;
-                               endcase
-                       end
-                       `INSN_POP_reg: begin    /* POP is 12 cycles! */
-                               case (cycle)
-                               0:      begin
-                                               cycle <= 1;
-                                               {registers[`REG_SPH],registers[`REG_SPL]} <=
-                                                       {registers[`REG_SPH],registers[`REG_SPL]} + 1;
-                                       end
-                               1:      begin
-                                               case (opcode[5:4])
-                                               `INSN_stack_AF: registers[`REG_F] <= rdata;
-                                               `INSN_stack_BC: registers[`REG_C] <= rdata;
-                                               `INSN_stack_DE: registers[`REG_E] <= rdata;
-                                               `INSN_stack_HL: registers[`REG_L] <= rdata;
-                                               endcase
-                                               {registers[`REG_SPH],registers[`REG_SPL]} <=
-                                                       {registers[`REG_SPH],registers[`REG_SPL]} + 1;
-                                               cycle <= 2;
-                                       end
-                               2:      begin
-                                               case (opcode[5:4])
-                                               `INSN_stack_AF: registers[`REG_A] <= rdata;
-                                               `INSN_stack_BC: registers[`REG_B] <= rdata;
-                                               `INSN_stack_DE: registers[`REG_D] <= rdata;
-                                               `INSN_stack_HL: registers[`REG_H] <= rdata;
-                                               endcase
-                                               cycle <= 0;
-                                       end
-                               endcase
-                       end
-                       `INSN_LDH_AC: begin
-                               case (cycle)
-                               0:      cycle <= 1;
-                               1: begin
-                                               cycle <= 0;
-                                               if (opcode[4])
-                                                       registers[`REG_A] <= rdata;
-                                       end
-                               endcase
-                       end
-                       `INSN_LDx_AHL: begin
-                               case (cycle)
-                               0:      cycle <= 1;
-                               1:      begin
-                                               cycle <= 0;
-                                               if (opcode[3])
-                                                       registers[`REG_A] <= rdata;
-                                               {registers[`REG_H],registers[`REG_L]} <=
-                                                       opcode[4] ? // if set, LDD, else LDI
-                                                       ({registers[`REG_H],registers[`REG_L]} - 1) :
-                                                       ({registers[`REG_H],registers[`REG_L]} + 1);
-                                       end
-                               endcase
-                       end
+                       `define WRITEBACK
+                       `include "allinsns.v"
+                       `undef WRITEBACK
+                       default:
+                               $stop;

                        endcase
                        state <= `STATE_FETCH;
                end
                endcase
 endmodule
                        endcase
                        state <= `STATE_FETCH;
                end
                endcase
 endmodule

-
-`timescale 1ns / 1ps
-module TestBench();
-       reg clk = 0;
-       wire [15:0] addr;
-       wire [7:0] data;
-       wire wr, rd;
-       reg [7:0] rom [2047:0];
-       
-       initial $readmemh("rom.hex", rom);
-       always #10 clk <= ~clk;
-       GBZ80Core core(
-               .clk(clk),
-               .busaddress(addr),
-               .busdata(data),
-               .buswr(wr),
-               .busrd(rd));
-       assign data = rd ? rom[addr] : 8'bzzzzzzzz;
-endmodule