`define INSN_BIT 9'b101xxxxxx
`define INSN_RES 9'b110xxxxxx
`define INSN_SET 9'b111xxxxxx
+`define INSN_ADD_HL 9'b000xx1001
`define INSN_cc_NZ 2'b00
`define INSN_cc_Z 2'b01
`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
+`ifdef verilator
+ `define EXEC_WRITE(ad, da) begin address <= (ad); wdata <= (da); wr <= 1; end
+ `define EXEC_READ(ad) begin address <= (ad); rd <= 1; end
+`else
+ `ifdef isim
+ `define EXEC_WRITE(ad, da) begin address <= (ad); wdata <= (da); wr <= 1; end
+ `define EXEC_READ(ad) begin address <= (ad); rd <= 1; end
+ `else
+/* Work around XST's retarded bugs :\ */
+ `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
+ `endif
+`endif
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,
- input irq, input [7:0] jaddr,
+ inout [15:0] bus0address, /* BUS_* is latched on STATE_FETCH. */
+ inout [7:0] bus0data,
+ inout bus0wr, bus0rd,
+ inout [15:0] bus1address, /* BUS_* is latched on STATE_FETCH. */
+ inout [7:0] bus1data,
+ inout bus1wr, bus1rd,
+ input irq, output reg irqack, input [7:0] jaddr,
output reg [1:0] state);
// reg [1:0] state; /* State within this bus cycle (see STATE_*). */
reg [7:0] tmp, tmp2; /* Generic temporary regs. */
reg [7:0] buswdata;
- assign busdata = buswr ? buswdata : 8'bzzzzzzzz;
+ wire [7:0] busdata;
+
+ reg [15:0] busaddress;
+ reg buswr, busrd;
+
+ reg bootstrap_enb;
+
+ wire bus = ((busaddress[15:8] == 8'h00) && bootstrap_enb) || ((busaddress[15:7] == 9'b111111111) && (busaddress != 16'hFFFF)) /* 0 or 1 depending on which bus */
+ `ifdef isim
+ || (busaddress === 16'hxxxx) /* To avoid simulator glomulation. */
+ `endif
+ ;
+
+ assign bus0address = (bus == 0) ? busaddress : 16'bzzzzzzzzzzzzzzz;
+ assign bus1address = (bus == 1) ? busaddress : 16'bzzzzzzzzzzzzzzz;
+ assign bus0data = ((bus == 0) && buswr) ? buswdata : 8'bzzzzzzzz;
+ assign bus1data = ((bus == 1) && buswr) ? buswdata : 8'bzzzzzzzz;
+ assign busdata = (bus == 0) ? bus0data : bus1data;
+ assign bus0rd = (bus == 0) ? busrd : 1'b0;
+ assign bus1rd = (bus == 1) ? busrd : 1'b0;
+ assign bus0wr = (bus == 0) ? buswr : 1'b0;
+ assign bus1wr = (bus == 1) ? buswr : 1'b0;
reg ie, iedelay;
2'b0,
tmp[0]};
- assign sla = {tmp[6:0],0};
+ assign sla = {tmp[6:0],1'b0};
assign slaf = {(tmp[6:0] == 0 ? 1'b1 : 1'b0),
2'b0,
tmp[7]};
// 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),
+ assign swapf = {(tmp == 1'b0 ? 1'b1 : 1'b0),
3'b0};
- assign srl = {0,tmp[7:1]};
+ assign srl = {1'b0,tmp[7:1]};
assign srlf = {(tmp[7:1] == 0 ? 1'b1 : 1'b0),
2'b0,
tmp[0]};
);
initial begin
- registers[ 0] <= 0;
- registers[ 1] <= 0;
- registers[ 2] <= 0;
- registers[ 3] <= 0;
- registers[ 4] <= 0;
- registers[ 5] <= 0;
- registers[ 6] <= 0;
- registers[ 7] <= 0;
- registers[ 8] <= 0;
- registers[ 9] <= 0;
- registers[10] <= 0;
- registers[11] <= 0;
+ `_A <= 0;
+ `_B <= 0;
+ `_C <= 0;
+ `_D <= 0;
+ `_E <= 0;
+ `_F <= 0;
+ `_H <= 0;
+ `_L <= 0;
+ `_PCH <= 0;
+ `_PCL <= 0;
+ `_SPH <= 0;
+ `_SPL <= 0;
rd <= 1;
wr <= 0;
newcycle <= 1;
state <= `STATE_WRITEBACK;
cycle <= 0;
twobyte <= 0;
+ bootstrap_enb <= 1;
+ irqack <= 0;
end
- always @(posedge clk)
+ always @(negedge clk) /* Set things up at the negedge to prepare for the posedge. */
case (state)
`STATE_FETCH: begin
if (newcycle) begin
busaddress <= address;
buswr <= wr;
busrd <= rd;
- if (wr)
+ if (wr) begin
buswdata <= wdata;
+ if (address == 16'hFF50)
+ bootstrap_enb <= 0;
+ end
end
+ end
+ `STATE_DECODE: begin /* Make sure this only happens for one clock. */
+ buswr <= 0;
+ busrd <= 0;
+ end
+ endcase
+
+ always @(posedge clk)
+ case (state)
+ `STATE_FETCH: begin
+ /* Things are set up in negedge so that something looking on posedge will get his shit. */
state <= `STATE_DECODE;
end
`STATE_DECODE: begin
if (newcycle) begin
if (twobyte) begin
- opcode <= {1,busdata};
+ opcode <= {1'b1,busdata};
twobyte <= 0;
end else if (ie && irq)
opcode <= `INSN_VOP_INTR;
else
- opcode <= {0,busdata};
- rdata <= busdata;
+ opcode <= {1'b0,busdata};
newcycle <= 0;
+ rdata <= busdata;
cycle <= 0;
end else begin
- if (rd) rdata <= busdata;
+ if (rd) rdata <= busdata; /* Still valid because peripherals are now expected to keep it held valid. */
cycle <= cycle + 1;
end
if (iedelay) begin
ie <= 1;
iedelay <= 0;
end
- buswr <= 0;
- busrd <= 0;
wr <= 0;
rd <= 0;
address <= 16'bxxxxxxxxxxxxxxxx; // Make it obvious if something of type has happened.
state <= `STATE_EXECUTE;
end
`STATE_EXECUTE: begin
+ `ifdef isim
+ if (opcode[7:0] === 8'bxxxxxxxx)
+ $stop;
+ `endif
casex (opcode)
`define EXECUTE
`include "allinsns.v"
git.joshuawise.com / fpgaboy.git / blobdiff