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This commit is contained in:
Nicholas Orlowsky 2024-04-07 23:39:15 -05:00
parent fdd6553f11
commit f2c0935b60
Signed by: nickorlow
GPG key ID: 838827D8C4611687
128 changed files with 39530 additions and 530 deletions
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cpu.sv
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@ -1,317 +1,317 @@
module cpu (
input wire system_ready,
output bit [7:0] memory[0:4095],
input wire clk_in,
input wire keyboard[15:0],
input wire [7:0] random_number,
input wire [7:0] rd_memory_data,
output int cycle_counter,
output wire [15:0] program_counter,
output wire [7:0] vram[0:1023],
output wire [7:0] sound_timer
output logic [11:0] rd_memory_address,
output logic [11:0] wr_memory_address,
output logic [7:0] wr_memory_data,
output logic wr_go,
output logic lcd_clk,
output logic lcd_data,
output logic [5:0] led
);
bit halt;
int watch_key;
logic [7:0] vram [0:1023];
logic [15:0] stack[0:15];
logic [15:0] index_reg;
logic [3:0] stack_pointer;
logic [7:0] registers[0:15];
logic [15:0] opcode;
logic [7:0] delay_timer;
`ifdef DUMMY_GPU
gpu gpu(
`endif
`ifndef DUMMY_GPU
st7920_serial_driver gpu(
`endif
clk_in,
1'b1,
vram,
lcd_clk,
lcd_data,
led
);
logic [15:0] scratch;
logic [15:0] scratch2;
logic [7:0] scratch_8;
logic [7:0] scratch_82;
logic [31:0] x_cord;
logic [31:0] y_cord;
logic [7:0] size;
logic screen_pixel;
logic [7:0] sprite_pixel;
task write_pixels;
input [31:0] x;
input [31:0] y;
int i;
begin
// bottom left
i = (y*128*2) + x*2 +127;
begin
// bottom left
`define BLP ((y*128*2) + x*2 +127)
if (vram[`BLP/8][7-(`BLP%8)] == 1) begin
registers[15] <= 1;
end
vram[`BLP/8][7-(`BLP%8)] <= 1;
if (vram[i/8][7-(i%8)] == 1) begin
registers[15] = 1;
end
// bottom right
`define BRP ((y*128*2) + x*2 +128)
vram[`BRP/8][7-(`BRP%8)] <= 1;
vram[i/8][7-(i%8)] ^= 1;
// top left
`define TLP ((y*128*2) + x*2-1)
vram[`TLP/8][7-(`TLP%8)] <= 1;
// bottom right
i = (y*128*2) + x*2 +128;
vram[i/8][7-(i%8)] ^= 1;
// top left
i = (y*128*2) + x*2-1;
vram[i/8][7-(i%8)] ^= 1;
// top right
i = (y*128*2) + x*2;
vram[i/8][7-(i%8)] ^= 1;
end
// top right
`define TRP ((y*128*2) + x*2)
vram[`TRP/8][7-(`TRP%8)] <= 1;
end
endtask
always_ff @(negedge clk_in) begin
if (system_ready) 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);
logic [15:0] program_counter;
if (cycle_counter % 20 == 0) begin
if (delay_timer > 0) delay_timer--;
if (sound_timer > 0) sound_timer--;
logic [7:0] registers[0:15];
logic [15:0] index_reg;
logic [15:0] stack[0:15];
logic [3:0] stack_pointer;
logic [15:0] opcode;
logic [7:0] sound_timer;
logic [7:0] delay_timer;
typedef enum {ST_FETCH_HI, ST_FETCH_LO, ST_FETCH_LO2, ST_DECODE, ST_EXEC, ST_DRAW, ST_FETCH_MEM, ST_WB, ST_CLEANUP, ST_HALT} cpu_state;
cpu_state state;
typedef enum {INIT, DRAW} draw_stage;
typedef enum {CLS, LD, DRW, JP} cpu_opcode;
typedef enum {REG, IDX_REG, BYTE, MEM, SPRITE_MEM} data_type;
struct {
draw_stage stage;
logic [4:0] r;
logic [4:0] c;
logic [7:0] x;
logic [7:0] y;
} draw_state;
struct {
cpu_opcode op;
data_type src;
data_type dst;
logic [3:0] dst_reg;
logic [3:0] src_reg;
logic [11:0] src_byte;
logic [(8*16)-1:0] src_sprite;
logic [11:0] src_sprite_addr;
logic [3:0] src_sprite_vx;
logic [3:0] src_sprite_vy;
logic [7:0] src_sprite_x;
logic [7:0] src_sprite_y;
logic [4:0] src_sprite_sz;
logic [4:0] src_sprite_idx;
logic [11:0] src_addr;
logic [11:0] dst_addr;
} instr;
initial begin
state = ST_FETCH_HI;
cycle_counter = 0;
program_counter = 'h200;
wr_go = 0;
for (int i = 0; i < 2048; i++) begin
vram[i] = 0;
end
end
casez (opcode)
'h00E0: begin
$display("HW : INSTR CLS");
for (int i = 0; i < 2048; i++) begin
vram[i] = 0;
always_ff @(posedge clk_in) begin
case (state)
ST_FETCH_HI: begin
rd_memory_address <= program_counter[11:0];
program_counter <= program_counter + 1;
state <= ST_FETCH_LO;
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;
ST_FETCH_LO: begin
rd_memory_address <= program_counter[11:0];
program_counter <= program_counter - 1;
opcode <= { rd_memory_data, 8'h00 };
$display("CPU : Opcode HI is %h", rd_memory_data);
state <= ST_FETCH_LO2;
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;
ST_FETCH_LO2: begin
opcode <= { opcode[15:8], rd_memory_data};
$display("CPU : Opcode LO is %h", rd_memory_data);
state <= ST_DECODE;
end
end
'h5??0: begin
$display("HW : INSTR SE Vx, Vy");
if (registers[(opcode&'h00F0)>>4] == registers[(opcode&'h0F00)>>8]) begin
program_counter += 2;
ST_DECODE: begin
casez (opcode)
16'h00E0: begin
instr.op <= CLS;
state <= ST_CLEANUP;
program_counter <= program_counter + 2;
end
16'h1???: begin
instr.op <= JP;
instr.src_byte <= opcode[11:0];
state <= ST_EXEC;
end
16'h6???: begin
$display("Instruction is LD Vx, Byte");
instr.op <= LD;
instr.src <= BYTE;
instr.src_byte <= {4'h00, opcode[7:0]};
instr.dst <= REG;
instr.dst_reg <= opcode[11:8];
state <= ST_EXEC;
end
16'hA???: begin
$display("Instruction is LD I, Byte");
instr.op <= LD;
instr.src <= BYTE;
instr.src_byte <= opcode[11:0];
instr.dst <= IDX_REG;
state <= ST_EXEC;
end
16'hD???: begin
instr.op <= DRW;
instr.src <= SPRITE_MEM;
instr.src_sprite_sz <= {1'b0, opcode[3:0]};
instr.src_sprite_addr <= index_reg[11:0];
instr.src_sprite_vx <= opcode[11:8];
instr.src_sprite_vy <= opcode[7:4];
instr.src_sprite_idx <= 0;
state <= ST_FETCH_MEM;
end
default: begin
$display("ILLEGAL INSTRUCTION %h at PC 0x%h (%0d)", opcode, program_counter, program_counter);
$fatal();
end
endcase
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];
registers[15] = 0;
end
'h8??2: begin
$display("HW : INSTR AND Vx, Vy");
registers[(opcode&'h0F00)>>8] &= registers[(opcode&'h00F0)>>4];
registers[15] = 0;
end
'h8??3: begin
$display("HW : INSTR XOR Vx, Vy");
registers[(opcode&'h0F00)>>8] ^= registers[(opcode&'h00F0)>>4];
registers[15] = 0;
end
'h8??4: begin
$display("HW : INSTR ADD Vx, Vy");
scratch_8 = registers[(opcode&'h0F00)>>8];
registers[(opcode&'h0F00)>>8] += registers[(opcode&'h00F0)>>4];
registers[15] = {7'b0000000, scratch_8 > registers[(opcode&'h0F00)>>8]};
end
'h8??5: begin
$display("HW : INSTR SUB Vx, Vy");
scratch_8 = registers[(opcode&'h0F00)>>8];
registers[(opcode&'h0F00)>>8] -= registers[(opcode&'h00F0)>>4];
registers[15] = {7'b0000000, scratch_8 >= registers[(opcode&'h0F00)>>8]};
end
'h8??6: begin
$display("HW : INSTR SHR Vx {, Vy}");
scratch_8 = registers[(opcode&'h0F00)>>8];
registers[(opcode&'h0F00)>>8] = registers[(opcode&'h00F0)>>4] >> 1;
registers[15] = {7'b0000000, ((scratch_8 & 8'h01) == 8'h01)};
end
'h8??7: begin
$display("HW : INSTR SUBN Vx, Vy");
scratch_8 = registers[(opcode&'h00F0)>>4];
scratch_82 = registers[(opcode&'h0F00)>>8];
registers[(opcode & 'h0F00) >> 8] = registers[(opcode & 'h00F0) >> 4] - registers[(opcode & 'h0F00) >> 8];
registers[15] = {7'b0000000, (scratch_8 >= scratch_82)};
end
'h8??E: begin
$display("HW : INSTR SHL Vx {, Vy}");
scratch_8 = registers[(opcode&'h0F00)>>8];
registers[(opcode&'h0F00)>>8] = registers[(opcode&'h00F0)>>4] << 1;
registers[15] = {7'b0000000, (scratch_8[7])};
end
'h9??0: begin
$display("HW : INSTR SNE Vx, Vy");
if (registers[(opcode&'h00F0)>>4] != registers[(opcode&'h0F00)>>8]) begin
program_counter += 2;
end
end
'hA???: begin
$display("HW : INSTR LD I, addr");
index_reg = (opcode & 'h0FFF);
end
'hb???: begin
$display("HW : INSTR JP V0, addr");
program_counter = {8'h00, registers[0]} + (opcode & 'h0FFF) - 2;
end
'hc???: begin
$display("HW : RND Vx, addr");
// TODO: use a real RNG module, this is not synthesizeable
scratch = {8'h00, random_number} % 16'h0100;
scratch2 = (opcode & 'h00FF);
registers[(opcode&'h0F00)>>8] = scratch[7:0] & scratch2[7:0];
end
'hD???: begin
$display("HW : INSTR DRW Vx, Vy, nibble");
if (cycle_counter % 20 != 0) begin
halt = 1;
end else begin
halt = 0;
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 (int r = 0; r < size; r++) begin
for (int c = 0; c < 8; c++) begin
if (r + y_cord >= 32 || x_cord + c >= 64) continue;
sprite_pixel = memory[{16'h0000, index_reg}+r] & ('h80 >> c);
if (|sprite_pixel) begin
write_pixels(x_cord + c, r+y_cord);
end
ST_FETCH_MEM: begin
if (instr.src == MEM) begin
if (rd_memory_address == instr.src_addr) begin
instr.src_byte <= { 4'h0, rd_memory_data};
instr.src <= BYTE;
state <= ST_EXEC;
end else begin
rd_memory_address <= instr.src_addr;
end
end
end
end
end
'hE?9E: begin
$display("HW : INSTR SKP Vx");
scratch_8 = registers[(opcode&'h0F00)>>8];
if (keyboard[scratch_8[3:0]] == 1) begin
program_counter += 2;
end
end
'hE?A1: begin
$display("HW : INSTR SNE Vx");
scratch_8 = registers[(opcode&'h0F00)>>8];
if (keyboard[scratch_8[3:0]] != 1) begin
program_counter += 2;
end
end
'hF?07: begin
$display("HW : INSTR LD Vx, DT");
registers[(opcode&'h0F00)>>8] = delay_timer;
end
'hF?0A: begin
$display("HW : INSTR LD Vx, K");
halt = 1;
for (int i = 0; i < 16; i++) begin
if (watch_key == 255) begin
if (keyboard[i]) begin
watch_key = i;
if (instr.src == SPRITE_MEM) begin
if (instr.src_sprite_idx == 0) begin
rd_memory_address <= instr.src_sprite_addr + {7'b0000000, instr.src_sprite_idx};
instr.src_sprite_idx <= instr.src_sprite_idx + 1;
end else if (instr.src_sprite_idx <= instr.src_sprite_sz) begin
rd_memory_address <= instr.src_sprite_addr + {7'b0000000, instr.src_sprite_idx};
instr.src_sprite_idx <= instr.src_sprite_idx + 1;
for (int l = 0; l < 8; l++)
instr.src_sprite[(instr.src_sprite_idx)*8+l] <= rd_memory_data[7-l];
$display("%b", rd_memory_data);
end else begin
instr.src_sprite_x <= registers[instr.src_sprite_vx] % 8'd64;
instr.src_sprite_y <= registers[instr.src_sprite_vy] % 8'd32;
state <= ST_DRAW;
draw_state.stage <= INIT;
end
end
end else begin
if (!keyboard[watch_key]) begin
halt = 0;
watch_key = 255;
end
ST_HALT: begin end
ST_DRAW: begin
if (draw_state.stage == INIT) begin
draw_state.x <= instr.src_sprite_x;
draw_state.y <= instr.src_sprite_y;
draw_state.r <= 0;
draw_state.c <= 0;
draw_state.stage <= DRAW;
registers[15] <= 0;
end else begin
if (draw_state.r == instr.src_sprite_sz + 1) begin
$display("sprite is %0d big at coord %d %d sprite=%b idx=%0d", instr.src_sprite_sz, instr.src_sprite_x, instr.src_sprite_y, instr.src_sprite, instr.src_sprite_addr);
state <= ST_CLEANUP;
program_counter <= program_counter + 2;
end else begin
if (draw_state.c == 5'd8) begin
draw_state.c <= 0;
draw_state.r <= draw_state.r + 1;
end else begin
/* verilator lint_off WIDTHEXPAND */
if (draw_state.r + instr.src_sprite_y < 32 && draw_state.c + instr.src_sprite_x < 64) begin
`define DRAW_PX ((draw_state.r + instr.src_sprite_y)*64 + (draw_state.c + instr.src_sprite_x))
/* verilator lint_off WIDTHEXPAND */
if (instr.src_sprite[(draw_state.r*8) + draw_state.c]) begin
write_pixels(draw_state.c + instr.src_sprite_x, draw_state.r + instr.src_sprite_y);
end
end
draw_state.c <= draw_state.c + 1;
end
end
end
end
end
end
'hF?15: begin
$display("HW : INSTR LD DT, Vx");
delay_timer = registers[(opcode&'h0F00)>>8];
end
'hF?18: begin
$display("HW : INSTR LD ST, Vx");
sound_timer = registers[(opcode&'h0F00)>>8];
end
'hF?1E: begin
$display("HW : INSTR ADD I, Vx");
index_reg = index_reg + {8'h00, registers[(opcode&'h0F00)>>8]};
end
'hF?29: begin
$display("HW : INSTR LDL F, Vx");
index_reg = registers[(opcode&'h0F00)>>8] * 5;
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 (bit [7:0] i8 = 0; i8 <= scratch[7:0]; i8++) begin
scratch2 = index_reg + {8'h00, i8};
memory[scratch2[11:0]] = registers[i8[3:0]];
ST_EXEC: begin
$display("CPU : IN EXEC");
case (instr.op)
LD: begin
if (instr.src == REG) begin
instr.src_byte <= { 4'h0, registers[instr.src_reg] };
instr.src <= BYTE;
end
end
JP: begin
program_counter <= {4'h00, instr.src_byte};
state <= ST_CLEANUP;
end
endcase
case (instr.op)
LD,
DRW,
CLS: begin
program_counter <= program_counter + 2;
state <= ST_WB;
end
endcase
end
index_reg++;
end
'hF?65: begin
$display("HW : INSTR LD Vx, [I]");
scratch = (opcode & 'h0F00) >> 8;
for (bit [7:0] i8 = 0; i8 <= scratch[7:0]; i8++) begin
scratch2 = index_reg + {8'h00, i8};
registers[i8[3:0]] = memory[scratch2[11:0]];
ST_WB: begin
$display("CPU : IN WB");
if (instr.src != BYTE)
$fatal();
case (instr.dst)
MEM: begin
wr_memory_address <= instr.dst_addr;
wr_memory_data <= instr.src_byte[7:0];
wr_go <= 1'b1;
$display("writing back byte %b to %h", instr.src_byte, instr.dst_addr);
end
REG: registers[instr.dst_reg] <= instr.src_byte[7:0];
IDX_REG: index_reg <= {4'h0, instr.src_byte};
endcase
state <= ST_CLEANUP;
end
ST_CLEANUP: begin
wr_go <= 0;
state <= ST_FETCH_HI;
end
index_reg++;
end
default: $display("HW : ILLEGAL INSTRUCTION");
endcase
if (!halt) program_counter += 2;
cycle_counter++;
end
cycle_counter <= cycle_counter + 1;
end
endmodule