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library ieee;
library work;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.numeric_std.all;
use work.ppu_consts.all;
use work.ppu_pceg_consts.all;
-- TODO: add input stable / output stable pipeline stages if this doesn't work with propagation delays
entity ppu_sprite_bg is port(
-- inputs
CLK : in std_logic; -- system clock
RESET : in std_logic; -- reset clock counter
PL_STAGE : in ppu_sprite_bg_pl_state; -- pipeline stage
OE : in std_logic; -- output enable (of CIDX)
X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
-- aux inputs
BG_SHIFT_X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
BG_SHIFT_Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
-- used memory blocks
BAM_ADDR : out std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
BAM_DATA : in std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0);
TMM_ADDR : out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
TMM_DATA : in std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
-- outputs
CIDX : out std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0)); -- output color
end ppu_sprite_bg;
architecture Behavioral of ppu_sprite_bg is
component ppu_sprite_transform port(
XI : in unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0); -- pixel position relative to tile
YI : in unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0); -- pixel position relative to tile
FLIP_H, FLIP_V : in std_logic; -- flip sprite
XO : out unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0); -- new pixel position relative to tile
YO : out unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0)); -- new pixel position relative to tile
end component;
-- BAM and TMM in/out temp + registers
signal T_BAM_ADDR, R_BAM_ADDR : std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0) := (others => '0');
signal T_BAM_DATA, R_BAM_DATA : std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0) := (others => '0');
signal T_TMM_ADDR, R_TMM_ADDR : std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0) := (others => '0');
signal T_TMM_DATA, R_TMM_DATA : std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0) := (others => '0');
-- docs/architecture.md#background-attribute-memory
alias BAM_DATA_FLIP_H is R_BAM_DATA(14); -- flip horizontally
alias BAM_DATA_FLIP_V is R_BAM_DATA(13); -- flip vertically
alias BAM_DATA_TILE_IDX is R_BAM_DATA(9 downto 0); -- tilemap tile index
alias BAM_DATA_COL_IDX is R_BAM_DATA(12 downto 10); -- palette for sprite
-- auxiliary signals (temp variables)
signal PIXEL_ABS_X, PIXEL_ABS_Y : integer := 0; -- absolute pixel position (relative to BG canvas instead of viewport)
signal TILE_IDX_X, TILE_IDX_Y : integer := 0; -- background canvas tile grid xy
signal TILE_PIDX_X, TRANS_TILE_PIDX_X : unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0) := (others => '0'); -- x position of pixel within tile (local tile coords)
signal TILE_PIDX_Y, TRANS_TILE_PIDX_Y : unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0) := (others => '0'); -- y position of pixel within tile (local tile coords)
signal TRANS_TILE_PIDX : integer := 0; -- index of pixel within tile (reading order)
signal TILEMAP_WORD_OFFSET : integer := 0; -- word offset from tile start address in TMM
signal PIXEL_BIT_OFFSET : integer := 0; -- pixel index within word of TMM
signal TMM_DATA_PAL_IDX : std_logic_vector(PPU_PALETTE_COLOR_WIDTH-1 downto 0); -- color of palette
signal T_CIDX : std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0) := (others => '0'); -- output color buffer/register
begin
-- output drivers
CIDX <= T_CIDX when OE = '1' else (others => 'Z');
BAM_ADDR <= R_BAM_ADDR when PL_STAGE = PL_BG_BAM_ADDR else (others => 'Z');
TMM_ADDR <= R_TMM_ADDR when PL_STAGE = PL_BG_TMM_ADDR else (others => 'Z');
T_BAM_DATA <= BAM_DATA;
T_TMM_DATA <= TMM_DATA;
-- CIDX combination
T_CIDX <= BAM_DATA_COL_IDX & TMM_DATA_PAL_IDX;
-- BAM address calculations
PIXEL_ABS_X <= to_integer(unsigned(X)) + to_integer(unsigned(BG_SHIFT_X)); -- pixel position relative to background canvas
PIXEL_ABS_Y <= to_integer(unsigned(Y)) + to_integer(unsigned(BG_SHIFT_Y)); -- pixel position relative to background canvas
TILE_IDX_X <= PIXEL_ABS_X / 16; -- tile grid index
TILE_IDX_Y <= PIXEL_ABS_Y / 16; -- tile grid index
TILE_PIDX_X <= to_unsigned(PIXEL_ABS_X - TILE_IDX_X * 16, TILE_PIDX_X'length); -- (sprite local) pixel coords
TILE_PIDX_Y <= to_unsigned(PIXEL_ABS_Y - TILE_IDX_Y * 16, TILE_PIDX_Y'length); -- (sprite local) pixel coords
T_BAM_ADDR <= std_logic_vector(to_unsigned((TILE_IDX_Y * integer(PPU_BG_CANVAS_TILES_H)) + TILE_IDX_X, PPU_BAM_ADDR_WIDTH));
-- BAM data dependant calculations
transform: component ppu_sprite_transform port map(
XI => TILE_PIDX_X,
YI => TILE_PIDX_Y,
FLIP_H => BAM_DATA_FLIP_H,
FLIP_V => BAM_DATA_FLIP_V,
XO => TRANS_TILE_PIDX_X,
YO => TRANS_TILE_PIDX_Y);
-- TMM address calculations
TRANS_TILE_PIDX <= integer(PPU_SPRITE_WIDTH) * to_integer(TRANS_TILE_PIDX_Y) + to_integer(TRANS_TILE_PIDX_X); -- pixel index of sprite
TILEMAP_WORD_OFFSET <= TRANS_TILE_PIDX / PPU_PIXELS_PER_TILE_WORD; -- word offset from starting word of sprite
PIXEL_BIT_OFFSET <= TRANS_TILE_PIDX mod PPU_PIXELS_PER_TILE_WORD; -- pixel bit offset
T_TMM_ADDR <= std_logic_vector(to_unsigned(PPU_SPRITE_WORD_COUNT * to_integer(unsigned(BAM_DATA_TILE_IDX)) + TILEMAP_WORD_OFFSET, PPU_TMM_ADDR_WIDTH)); -- TMM address
-- TMM DATA
with PIXEL_BIT_OFFSET select
TMM_DATA_PAL_IDX <= R_TMM_DATA(2 downto 0) when 0,
R_TMM_DATA(5 downto 3) when 1,
R_TMM_DATA(8 downto 6) when 2,
R_TMM_DATA(11 downto 9) when 3,
R_TMM_DATA(14 downto 12) when 4,
(others => '0') when others;
-- state machine (pipeline stage counter) + sync r/w
process(CLK, RESET)
begin
if RESET = '1' then
-- reset internal pipeline registers
R_BAM_ADDR <= (others => '0');
R_BAM_DATA <= (others => '0');
R_TMM_ADDR <= (others => '0');
R_TMM_DATA <= (others => '0');
elsif rising_edge(CLK) then
case PL_STAGE is
when PL_BG_BAM_ADDR =>
R_BAM_ADDR <= T_BAM_ADDR;
when PL_BG_BAM_DATA =>
R_BAM_DATA <= T_BAM_DATA;
when PL_BG_TMM_ADDR =>
R_TMM_ADDR <= T_TMM_ADDR;
when PL_BG_TMM_DATA =>
R_TMM_DATA <= T_TMM_DATA;
when others => null;
end case;
end if;
end process;
end Behavioral;
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