`define STATE_EXECUTE 2'h2
`define STATE_WRITEBACK 2'h3
-`define INSN_LD_reg_imm8 8'b00xxx110
-`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_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_LD_reg_imm8 9'b000xxx110
+`define INSN_HALT 9'b001110110
+`define INSN_LD_HL_reg 9'b001110xxx
+`define INSN_LD_reg_HL 9'b001xxx110
+`define INSN_LD_reg_reg 9'b001xxxxxx
+`define INSN_LD_reg_imm16 9'b000xx0001
+`define INSN_LD_SP_HL 9'b011111001
+`define INSN_PUSH_reg 9'b011xx0101
+`define INSN_POP_reg 9'b011xx0001
+`define INSN_LDH_AC 9'b0111x0010 // Either LDH A,(C) or LDH (C),A
+`define INSN_LDx_AHL 9'b0001xx010 // LDD/LDI A,(HL) / (HL),A
+`define INSN_ALU8 9'b010xxxxxx // 10 xxx yyy
+`define INSN_ALU8IMM 9'b011xxx110
+`define INSN_NOP 9'b000000000
+`define INSN_RST 9'b011xxx111
+`define INSN_RET 9'b0110x1001 // 1 = RETI, 0 = RET
+`define INSN_RETCC 9'b0110xx000
+`define INSN_CALL 9'b011001101
+`define INSN_CALLCC 9'b0110xx100 // Not that call/cc.
+`define INSN_JP_imm 9'b011000011
+`define INSN_JPCC_imm 9'b0110xx010
+`define INSN_ALU_A 9'b000xxx111
+`define INSN_JP_HL 9'b011101001
+`define INSN_JR_imm 9'b000011000
+`define INSN_JRCC_imm 9'b0001xx000
+`define INSN_INCDEC16 9'b000xxx011
+`define INSN_VOP_INTR 9'b011111100 // 0xFC is grabbed by the fetch if there is an interrupt pending.
+`define INSN_DI 9'b011110011
+`define INSN_EI 9'b011111011
+`define INSN_INCDEC_HL 9'b00011010x
+`define INSN_INCDEC_reg8 9'b000xxx10x
+`define INSN_LD8M_A 9'b0111x0000 // 1111 for ld A, x; 1110 for ld x, A; bit 1 specifies 16m8 or 8m8
+`define INSN_LD16M_A 9'b0111x1010 // 1111 for ld A, x; 1110 for ld x, A; bit 1 specifies 16m8 or 8m8
+`define INSN_LDBCDE_A 9'b0000xx010
+`define INSN_TWO_BYTE 9'b011001011 // prefix for two-byte opqodes
+`define INSN_ALU_EXT 9'b100xxxxxx
+`define INSN_BIT 9'b101xxxxxx
+`define INSN_RES 9'b110xxxxxx
+`define INSN_SET 9'b111xxxxxx
`define INSN_cc_NZ 2'b00
`define INSN_cc_Z 2'b01
`define INSN_alu_CPL 3'b101
`define INSN_alu_SCF 3'b110
`define INSN_alu_CCF 3'b111
+`define INSN_alu_RLC 3'b000
+`define INSN_alu_RRC 3'b001
+`define INSN_alu_RL 3'b010
+`define INSN_alu_RR 3'b011
+`define INSN_alu_DA_SLA 3'b100
+`define INSN_alu_CPL_SRA 3'b101
+`define INSN_alu_SCF_SWAP 3'b110
+`define INSN_alu_CCF_SRL 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_NEWCYCLE_TWOBYTE begin newcycle <= 1; rd <= 1; wr <= 0; twobyte <= 1; 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
output reg buswr, output reg busrd,
input irq, input [7:0] jaddr,
output reg [1:0] state);
-
+
// reg [1:0] state; /* State within this bus cycle (see STATE_*). */
reg [2:0] cycle; /* Cycle for instructions. */
reg [15:0] address; /* Address for the next bus operation. */
- reg [7:0] opcode; /* Opcode from the current machine cycle. */
-
+ reg [8:0] 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, wr, newcycle;
+ reg rd, wr, newcycle, twobyte;
reg [7:0] tmp, tmp2; /* Generic temporary regs. */
reg [7:0] buswdata;
assign busdata = buswr ? buswdata : 8'bzzzzzzzz;
-
+
reg ie, iedelay;
-
+
+ wire [7:0] rlc,rrc,rl,rr,sla,sra,swap,srl;
+ wire [3:0] rlcf,rrcf,rlf,rrf,slaf,sraf,swapf,srlf;
+ wire [7:0] alu_res;
+ wire [3:0] f_res;
+
+ assign rlc = {tmp[6:0],tmp[7]};
+ assign rlcf = {(tmp == 0 ? 1'b1 : 1'b0)
+ ,2'b0,
+ tmp[7]};
+
+ assign rrc = {tmp[0],tmp[7:1]};
+ assign rrcf = {(tmp == 0 ? 1'b1 : 1'b0),
+ 2'b0,
+ tmp[0]};
+
+ assign rl = {tmp[6:0],`_F[4]};
+ assign rlf = {({tmp[6:0],`_F[4]} == 0 ? 1'b1 : 1'b0),
+ 2'b0,
+ tmp[7]};
+
+ assign rr = {`_F[4],tmp[7:1]};
+ assign rrf = {({tmp[4],tmp[7:1]} == 0 ? 1'b1 : 1'b0),
+ 2'b0,
+ tmp[0]};
+
+ assign sla = {tmp[6:0],0};
+ assign slaf = {(tmp[6:0] == 0 ? 1'b1 : 1'b0),
+ 2'b0,
+ tmp[7]};
+
+ assign sra = {tmp[7],tmp[7:1]};
+// assign sraf = {(tmp[7:1] == 0 ? 1'b1 : 1'b0),2'b0,tmp[0]}; now in assign srlf =
+
+ assign swap = {tmp[3:0],tmp[7:4]};
+ assign swapf = {(tmp == 0 ? 1'b1 : 1'b0),
+ 3'b0};
+
+ assign srl = {0,tmp[7:1]};
+ assign srlf = {(tmp[7:1] == 0 ? 1'b1 : 1'b0),
+ 2'b0,
+ tmp[0]};
+ assign sraf = srlf;
+
+ /* Y U Q */
+ assign {alu_res,f_res} =
+ opcode[5] ? (
+ opcode[4] ? (
+ opcode[3] ? {srl,srlf} : {swap,swapf}
+ ) : (
+ opcode[3] ? {sra,sraf} : {sla,slaf}
+ )
+ ) : (
+ opcode[4] ? (
+ opcode[3] ? {rr,rrf} : {rl,rlf}
+ ) : (
+ opcode[3] ? {rrc,rrcf} : {rlc,rlcf}
+ )
+ );
+
initial begin
registers[ 0] <= 0;
registers[ 1] <= 0;
opcode <= 0;
state <= `STATE_WRITEBACK;
cycle <= 0;
+ twobyte <= 0;
end
always @(posedge clk)
case (state)
`STATE_FETCH: begin
if (newcycle) begin
- busaddress <= {registers[`REG_PCH], registers[`REG_PCL]};
+ busaddress <= `_PC;
buswr <= 0;
busrd <= 1;
end else begin
end
`STATE_DECODE: begin
if (newcycle) begin
- if (ie && irq)
+ if (twobyte) begin
+ opcode <= {1,busdata};
+ twobyte <= 0;
+ end else if (ie && irq)
opcode <= `INSN_VOP_INTR;
else
- opcode <= busdata;
+ opcode <= {0,busdata};
rdata <= busdata;
newcycle <= 0;
cycle <= 0;
git.joshuawise.com / fpgaboy.git / blobdiff