227 lines
8.2 KiB
Systemverilog
227 lines
8.2 KiB
Systemverilog
module yayacemu (
|
|
input wire clk_in
|
|
);
|
|
import "DPI-C" function void init_screen();
|
|
|
|
wire [31:0] vram [0:2047];
|
|
bit [7:0] memory [0:4095];
|
|
wire [7:0] registers [0:15];
|
|
logic [3:0] stack_pointer;
|
|
wire [15:0] stack [0:15];
|
|
|
|
logic [15:0] index_reg;
|
|
logic rom_ready;
|
|
logic [15:0] program_counter;
|
|
|
|
rom_loader rl (memory, rom_ready);
|
|
chip8_cpu cpu (memory, clk_in, vram, stack, index_reg, stack_pointer, registers, program_counter);
|
|
chip8_gpu gpu (vram);
|
|
|
|
initial begin
|
|
program_counter = 'h200;
|
|
stack_pointer = 4'b0000;
|
|
init_screen();
|
|
end
|
|
|
|
endmodule
|
|
|
|
module chip8_cpu(
|
|
output bit [7:0] memory [0:4095],
|
|
input wire clk_in,
|
|
output wire [31:0] vram [0:2047],
|
|
output wire [15:0] stack [0:15],
|
|
output wire [15:0] index_reg,
|
|
output wire [3:0] stack_pointer,
|
|
output wire [7:0] registers [0:15],
|
|
output wire [15:0] program_counter
|
|
);
|
|
|
|
logic [15:0] opcode;
|
|
logic [15:0] scratch;
|
|
logic [15:0] scratch2;
|
|
|
|
logic [31:0] x_cord;
|
|
logic [31:0] y_cord;
|
|
logic [7:0] size;
|
|
logic [31:0] screen_pixel;
|
|
logic [7:0] sprite_pixel;
|
|
|
|
int i;
|
|
logic [7:0] i8;
|
|
|
|
int r;
|
|
int c;
|
|
always_ff @(posedge clk_in) begin
|
|
opcode = {memory[program_counter+0], memory[program_counter+1]};
|
|
$display("HW : opcode is 0x%h (%b)", opcode, opcode);
|
|
$display("HW : PC %0d 0x%h", program_counter, program_counter);
|
|
|
|
casez(opcode)
|
|
'h00E0: begin
|
|
$display("HW : INSTR CLS");
|
|
for(i = 0; i < 2048; i++) begin
|
|
vram[i] = 0;
|
|
end
|
|
end
|
|
'h00EE: begin
|
|
$display("HW : INSTR RET");
|
|
stack_pointer--;
|
|
program_counter = stack[stack_pointer];
|
|
end
|
|
'h0???: $display("HW : INSTR SYS addr (Treating as NOP)");
|
|
'h1???: begin
|
|
$display("HW : INSTR JP addr");
|
|
program_counter = (opcode & 'h0FFF) - 2;
|
|
end
|
|
'h2???: begin
|
|
$display("HW : INSTR CALL addr");
|
|
stack[stack_pointer] = program_counter;
|
|
stack_pointer++;
|
|
program_counter = (opcode & 'h0FFF) - 2;
|
|
end
|
|
'h3???: begin
|
|
$display("HW : INSTR SE Vx, byte");
|
|
scratch = (opcode & 'h00FF);
|
|
if (scratch[7:0] == registers[(opcode & 'h0F00) >> 8]) begin
|
|
program_counter += 2;
|
|
end
|
|
end
|
|
'h4???: begin
|
|
$display("HW : INSTR SNE Vx, byte");
|
|
scratch = (opcode & 'h00FF);
|
|
if (scratch[7:0] != registers[(opcode & 'h0F00) >> 8]) begin
|
|
program_counter += 2;
|
|
end
|
|
end
|
|
'h5??0: begin
|
|
$display("HW : INSTR SE Vx, Vy");
|
|
if (registers[(opcode & 'h00F0) >> 4] == registers[(opcode & 'h0F00) >> 8]) begin
|
|
program_counter += 2;
|
|
end
|
|
end
|
|
'h6???: begin
|
|
$display("HW : INSTR LD Vx, byte");
|
|
scratch = (opcode & 'h00FF);
|
|
registers[(opcode & 'h0F00) >> 8] = scratch[7:0];
|
|
end
|
|
'h7???: begin
|
|
$display("HW : INSTR ADD Vx, byte");
|
|
scratch = (opcode & 'h00FF);
|
|
registers[(opcode & 'h0F00) >> 8] += scratch[7:0];
|
|
end
|
|
'h8??0: begin
|
|
$display("HW : INSTR LD Vx, Vy");
|
|
registers[(opcode & 'h0F00) >> 8] = registers[(opcode & 'h00F0) >> 4];
|
|
end
|
|
'h8??1: begin
|
|
$display("HW : INSTR OR Vx, Vy");
|
|
registers[(opcode & 'h0F00) >> 8] |= registers[(opcode & 'h00F0) >> 4];
|
|
end
|
|
'h8??2: begin
|
|
$display("HW : INSTR AND Vx, Vy");
|
|
registers[(opcode & 'h0F00) >> 8] &= registers[(opcode & 'h00F0) >> 4];
|
|
end
|
|
'h8??3: begin
|
|
$display("HW : INSTR XOR Vx, Vy");
|
|
registers[(opcode & 'h0F00) >> 8] ^= registers[(opcode & 'h00F0) >> 4];
|
|
end
|
|
'h8??4: begin
|
|
$display("HW : INSTR ADD Vx, Vy");
|
|
registers[(opcode & 'h0F00) >> 8] += registers[(opcode & 'h00F0) >> 4];
|
|
end
|
|
'h8??5: begin
|
|
$display("HW : INSTR SUB Vx, Vy");
|
|
registers[(opcode & 'h0F00) >> 8] -= registers[(opcode & 'h00F0) >> 4];
|
|
end
|
|
'h8??6: begin
|
|
$display("HW : INSTR SHR Vx {, Vy}");
|
|
registers[(opcode & 'h0F00) >> 8] = registers[(opcode & 'h00F0) >> 4]>> 1;
|
|
end
|
|
'h8??7: begin
|
|
$display("HW : INSTR SUBN Vx, Vy");
|
|
registers[(opcode & 'h0F00) >> 8] = registers[(opcode & 'h00F0) >> 4] - registers[(opcode & 'h0F00) >> 8];
|
|
end
|
|
'h8??E: begin
|
|
$display("HW : INSTR SHL Vx {, Vy}");
|
|
registers[(opcode & 'h0F00) >> 8] = registers[(opcode & 'h00F0) >> 4]<< 1;
|
|
end
|
|
'hA???: begin
|
|
$display("HW : INSTR LD I, addr");
|
|
index_reg = (opcode & 'h0FFF);
|
|
end
|
|
'hD???: begin
|
|
$display("HW : INSTR DRW Vx, Vy, nibble");
|
|
x_cord = {24'h000000, registers[(opcode & 'h0F00) >> 8]};
|
|
y_cord = {24'h000000, registers[(opcode & 'h00F0) >> 4]};
|
|
|
|
x_cord %= 64;
|
|
y_cord %= 32;
|
|
|
|
scratch = (opcode & 'h000F);
|
|
size = scratch[7:0];
|
|
registers[15] = 0;
|
|
|
|
for (r = 0; r < size; r++) begin
|
|
for ( c = 0; c < 8; c++) begin
|
|
screen_pixel = vram[((r + y_cord) * 64) + (x_cord + c)];
|
|
sprite_pixel = memory[{16'h0000, index_reg} + r] & ('h80 >> c);
|
|
|
|
if (|sprite_pixel) begin
|
|
if (screen_pixel == 32'hFFFFFFFF) begin
|
|
registers[15] = 1;
|
|
end
|
|
vram[((r + y_cord) * 64) + (x_cord + c)] ^= 32'hFFFFFFFF;
|
|
end
|
|
end
|
|
end
|
|
end
|
|
'hF?33: begin
|
|
$display("HW : INSTR LD B, Vx");
|
|
scratch = {8'h00, registers[(opcode & 'h0F00) >> 8]};
|
|
scratch2 = scratch % 10;
|
|
memory[index_reg + 2] = scratch2[7:0];
|
|
scratch /= 10;
|
|
scratch2 = scratch % 10;
|
|
memory[index_reg + 1] = scratch2[7:0];
|
|
scratch /= 10;
|
|
scratch2 = scratch % 10;
|
|
memory[index_reg + 0] = scratch2[7:0];
|
|
end
|
|
'hF?55: begin
|
|
$display("HW : INSTR LD [I], Vx");
|
|
scratch = (opcode & 'h0F00) >> 8;
|
|
for (i8 = 0; i8 <= scratch[7:0]; i8++) begin
|
|
scratch2 = index_reg + {8'h00, i8};
|
|
memory[scratch2[11:0]] = registers[i8[3:0]];
|
|
end
|
|
index_reg++;
|
|
end
|
|
'hF?65: begin
|
|
$display("HW : INSTR LD Vx, [I]");
|
|
scratch = (opcode & 'h0F00) >> 8;
|
|
for (i8 = 0; i8 <= scratch[7:0]; i8++) begin
|
|
scratch2 = index_reg + {8'h00, i8};
|
|
registers[i8[3:0]] = memory[scratch2[11:0]];
|
|
end
|
|
index_reg++;
|
|
end
|
|
'hF?1E: begin
|
|
$display("HW : INSTR ADD I, Vx");
|
|
index_reg = index_reg + {8'h00, registers[(opcode & 'h0F00) >> 8]};
|
|
end
|
|
default: $display("HW : ILLEGAL INSTRUCTION");
|
|
endcase
|
|
|
|
program_counter += 2;
|
|
end
|
|
endmodule
|
|
|
|
module chip8_gpu (
|
|
input wire [31:0] vram [0:2047]
|
|
);
|
|
import "DPI-C" function void draw_screen(logic [31:0] vram [0:2047]);
|
|
always_comb begin
|
|
draw_screen(vram);
|
|
end
|
|
endmodule
|