mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-12-29 11:31:42 +00:00
275 lines
7.2 KiB
Verilog
275 lines
7.2 KiB
Verilog
|
|
`include "hvsync_generator.v"
|
|
`include "sprite_bitmap.v"
|
|
`include "sprite_renderer.v"
|
|
`include "cpu8.v"
|
|
|
|
/*
|
|
A simple racing game with two sprites and a scrolling playfield.
|
|
This version uses the 8-bit CPU.
|
|
*/
|
|
|
|
module racing_game_cpu_top(clk, reset, hsync, vsync, hpaddle, vpaddle, rgb);
|
|
|
|
input clk, reset;
|
|
input hpaddle, vpaddle;
|
|
output hsync, vsync;
|
|
wire display_on;
|
|
wire [8:0] hpos;
|
|
wire [8:0] vpos;
|
|
output [3:0] rgb;
|
|
|
|
parameter PADDLE_X = 0; // paddle X coordinate
|
|
parameter PADDLE_Y = 1; // paddle Y coordinate
|
|
parameter PLAYER_X = 2; // player X coordinate
|
|
parameter PLAYER_Y = 3; // player Y coordinate
|
|
parameter ENEMY_X = 4; // enemy X coordinate
|
|
parameter ENEMY_Y = 5; // enemy Y coordinate
|
|
parameter ENEMY_DIR = 6; // enemy direction (1, -1)
|
|
parameter SPEED = 7; // player speed
|
|
parameter TRACKPOS_LO = 8; // track position (lo byte)
|
|
parameter TRACKPOS_HI = 9; // track position (hi byte)
|
|
|
|
parameter IN_HPOS = 8'h40; // CRT horizontal position
|
|
parameter IN_VPOS = 8'h41; // CRT vertical position
|
|
// flags: [0, 0, collision, vsync, hsync, vpaddle, hpaddle, display_on]
|
|
parameter IN_FLAGS = 8'h42;
|
|
|
|
reg [7:0] ram[0:15]; // 16 bytes of RAM
|
|
reg [7:0] rom[0:127]; // 128 bytes of ROM
|
|
|
|
wire [7:0] address_bus; // CPU address bus
|
|
reg [7:0] to_cpu; // data bus to CPU
|
|
wire [7:0] from_cpu; // data bus from CPU
|
|
wire write_enable; // write enable bit from CPU
|
|
|
|
// 8-bit CPU module
|
|
CPU cpu(.clk(clk),
|
|
.reset(reset),
|
|
.address(address_bus),
|
|
.data_in(to_cpu),
|
|
.data_out(from_cpu),
|
|
.write(write_enable));
|
|
|
|
// RAM write from CPU
|
|
always @(posedge clk)
|
|
if (write_enable)
|
|
ram[address_bus[3:0]] <= from_cpu;
|
|
|
|
// RAM read from CPU
|
|
always @(*)
|
|
casez (address_bus)
|
|
// RAM
|
|
8'b00??????: to_cpu = ram[address_bus[3:0]];
|
|
// special read registers
|
|
IN_HPOS: to_cpu = hpos[7:0];
|
|
IN_VPOS: to_cpu = vpos[7:0];
|
|
IN_FLAGS: to_cpu = {2'b0, frame_collision,
|
|
vsync, hsync, vpaddle, hpaddle, display_on};
|
|
// ROM
|
|
8'b1???????: to_cpu = rom[address_bus[6:0]];
|
|
default: to_cpu = 8'bxxxxxxxx;
|
|
endcase
|
|
|
|
// sync generator module
|
|
hvsync_generator hvsync_gen(
|
|
.clk(clk),
|
|
.reset(0),
|
|
.hsync(hsync),
|
|
.vsync(vsync),
|
|
.display_on(display_on),
|
|
.hpos(hpos),
|
|
.vpos(vpos)
|
|
);
|
|
|
|
// flags for player sprite renderer module
|
|
wire player_vstart = {1'b0,ram[PLAYER_Y]} == vpos;
|
|
wire player_hstart = {1'b0,ram[PLAYER_X]} == hpos;
|
|
wire player_gfx;
|
|
wire player_is_drawing;
|
|
|
|
// flags for enemy sprite renderer module
|
|
wire enemy_vstart = {1'b0,ram[ENEMY_Y]} == vpos;
|
|
wire enemy_hstart = {1'b0,ram[ENEMY_X]} == hpos;
|
|
wire enemy_gfx;
|
|
wire enemy_is_drawing;
|
|
|
|
// select player or enemy access to ROM
|
|
wire player_load = (hpos >= 256) && (hpos < 260);
|
|
wire enemy_load = (hpos >= 260);
|
|
// wire up car sprite ROM
|
|
// multiplex between player and enemy ROM address
|
|
wire [3:0] player_sprite_yofs;
|
|
wire [3:0] enemy_sprite_yofs;
|
|
wire [3:0] car_sprite_yofs = player_load ? player_sprite_yofs : enemy_sprite_yofs;
|
|
wire [7:0] car_sprite_bits;
|
|
car_bitmap car(
|
|
.yofs(car_sprite_yofs),
|
|
.bits(car_sprite_bits));
|
|
|
|
// player sprite renderer
|
|
sprite_renderer player_renderer(
|
|
.clk(clk),
|
|
.vstart(player_vstart),
|
|
.hstart(player_hstart),
|
|
.load(player_load),
|
|
.rom_addr(player_sprite_yofs),
|
|
.rom_bits(car_sprite_bits),
|
|
.gfx(player_gfx),
|
|
.in_progress(player_is_drawing));
|
|
|
|
// enemy sprite renderer
|
|
sprite_renderer enemy_renderer(
|
|
.clk(clk),
|
|
.vstart(enemy_vstart),
|
|
.hstart(enemy_hstart),
|
|
.load(enemy_load),
|
|
.rom_addr(enemy_sprite_yofs),
|
|
.rom_bits(car_sprite_bits),
|
|
.gfx(enemy_gfx),
|
|
.in_progress(enemy_is_drawing));
|
|
|
|
// collision detection logic
|
|
reg frame_collision;
|
|
always @(posedge clk)
|
|
if (player_gfx && (enemy_gfx || track_gfx))
|
|
frame_collision <= 1;
|
|
else if (vpos==0)
|
|
frame_collision <= 0;
|
|
|
|
// track graphics
|
|
wire track_offside = (hpos[7:5]==0) || (hpos[7:5]==7);
|
|
wire track_shoulder = (hpos[7:3]==3) || (hpos[7:3]==28);
|
|
wire track_gfx = (vpos[5:1]!=ram[TRACKPOS_LO][5:1]) && track_offside;
|
|
|
|
// RGB output
|
|
wire r = display_on && (player_gfx || enemy_gfx || track_shoulder);
|
|
wire g = display_on && (player_gfx || track_gfx);
|
|
wire b = display_on && (enemy_gfx || track_shoulder);
|
|
// RGBI (in IBGR order, intensity is 4th bit)
|
|
assign rgb = {1'b0,b,g,r};
|
|
|
|
//////////// CPU program code
|
|
|
|
`ifdef EXT_INLINE_ASM
|
|
initial begin
|
|
rom = '{
|
|
__asm
|
|
.arch femto8 ; FEMTO-8 architecture
|
|
.org 128 ; origin = 128 ($80)
|
|
.len 128 ; length = 128 ($80)
|
|
|
|
; define constants
|
|
.define PADDLE_X 0
|
|
.define PADDLE_Y 1
|
|
.define PLAYER_X 2
|
|
.define PLAYER_Y 3
|
|
.define ENEMY_X 4
|
|
.define ENEMY_Y 5
|
|
.define ENEMY_DIR 6
|
|
.define SPEED 7
|
|
.define TRACKPOS_LO 8
|
|
.define TRACKPOS_HI 9
|
|
|
|
.define IN_HPOS $40
|
|
.define IN_VPOS $41
|
|
.define IN_FLAGS $42
|
|
|
|
.define F_DISPLAY 1
|
|
.define F_HPADDLE 2
|
|
.define F_VPADDLE 4
|
|
.define F_HSYNC 8
|
|
.define F_VSYNC 16
|
|
.define F_COLLIDE 32
|
|
|
|
Start:
|
|
lda #128 ; load initial positions
|
|
sta PLAYER_X ; player_x = 128
|
|
sta ENEMY_X ; enemy_x = 128
|
|
sta ENEMY_Y ; enemy_y = 128
|
|
lda #180
|
|
sta PLAYER_Y ; player_y = 180
|
|
zero A
|
|
sta SPEED ; player speed = 0
|
|
inc A
|
|
sta ENEMY_DIR ; enemy dir = 1 (right)
|
|
; read horizontal paddle position
|
|
DisplayLoop:
|
|
lda #F_HPADDLE ; paddle flag -> A
|
|
ldb #IN_FLAGS ; addr of IN_FLAGS -> B
|
|
and none,[B] ; read B, AND with A
|
|
bz DisplayLoop ; loop until paddle flag set
|
|
ldb #IN_VPOS
|
|
mov A,[B] ; load vertical position -> A
|
|
sta PLAYER_X ; store player x position
|
|
; wait for vsync
|
|
lda #F_VSYNC
|
|
ldb #IN_FLAGS
|
|
WaitForVsyncOn:
|
|
and none,[B]
|
|
bz WaitForVsyncOn ; wait until VSYNC on
|
|
WaitForVsyncOff:
|
|
and none,[B]
|
|
bnz WaitForVsyncOff ; wait until VSYNC off
|
|
; check collision
|
|
lda #F_COLLIDE
|
|
ldb #IN_FLAGS
|
|
and none,[B] ; collision flag set?
|
|
bz NoCollision ; skip ahead if not
|
|
lda #16
|
|
sta SPEED ; speed = 16
|
|
NoCollision:
|
|
; update speed
|
|
ldb #SPEED
|
|
mov A,[B] ; speed -> A
|
|
inc A ; increment speed
|
|
bz MaxSpeed ; speed wraps to 0?
|
|
sta SPEED ; no, store speed
|
|
MaxSpeed:
|
|
mov A,[B] ; reload speed -> A
|
|
lsr A
|
|
lsr A
|
|
lsr A
|
|
lsr A ; divide speed by 16
|
|
; add to lo byte of track pos
|
|
ldb #TRACKPOS_LO
|
|
add B,[B] ; B <- speed/16 + trackpos_lo
|
|
swapab ; swap A <-> B
|
|
sta TRACKPOS_LO ; A -> trackpos_lo
|
|
swapab ; swap A <-> B again
|
|
bcc NoCarry ; carry flag from earlier add op
|
|
; add to hi byte of track pos
|
|
ldb #TRACKPOS_HI
|
|
mov B,[B] ; B <- trackpos_hi
|
|
inc b ; increment B
|
|
swapab ; swap A <-> B
|
|
sta TRACKPOS_HI ; A -> trackpos_hi
|
|
swapab ; swap A <-> B again
|
|
NoCarry:
|
|
; update enemy vert pos
|
|
ldb #ENEMY_Y
|
|
add A,[B]
|
|
sta ENEMY_Y ; enemy_y = enemy_y + speed/16
|
|
; update enemy horiz pos
|
|
ldb #ENEMY_X
|
|
mov A,[B]
|
|
ldb #ENEMY_DIR
|
|
add A,[B]
|
|
sta ENEMY_X ; enemy_x = enemy_x + enemy_dir
|
|
sub A,#64
|
|
and A,#127 ; A <- (enemy_x-64) & 127
|
|
bnz SkipXReverse ; skip if enemy_x is in range
|
|
; load ENEMY_DIR and negate
|
|
zero A
|
|
sub A,[B]
|
|
sta ENEMY_DIR ; enemy_dir = -enemy_dir
|
|
SkipXReverse:
|
|
; back to display loop
|
|
jmp DisplayLoop
|
|
__endasm
|
|
};
|
|
end
|
|
`endif
|
|
|
|
endmodule
|