diff options
Diffstat (limited to 'basys3/basys3.srcs/ppu_consts.vhd')
| -rw-r--r-- | basys3/basys3.srcs/ppu_consts.vhd | 73 |
1 files changed, 53 insertions, 20 deletions
diff --git a/basys3/basys3.srcs/ppu_consts.vhd b/basys3/basys3.srcs/ppu_consts.vhd index c063586..75b6168 100644 --- a/basys3/basys3.srcs/ppu_consts.vhd +++ b/basys3/basys3.srcs/ppu_consts.vhd @@ -1,22 +1,55 @@ +library ieee; +use ieee.math_real.all; + +-- https://docs.google.com/spreadsheets/d/1MU6K4c4PtMR_JXIpc3I0ZJdLZNnoFO7G2P3olCz6LSc package ppu_consts is - constant PPU_RAM_BUS_ADDR_WIDTH: natural := 16; -- RAM bus address width - constant PPU_RAM_BUS_DATA_WIDTH: natural := 16; -- RAM bus data width - constant PPU_FG_SPRITE_COUNT: natural := 128; -- amount of foreground sprites - constant PPU_COLOR_OUTPUT_DEPTH: natural := 4; -- VGA output channel depth - constant PPU_PALETTE_IDX_WIDTH: natural := 3; -- palette index width (within sprite) - constant PPU_PALETTE_WIDTH: natural := 3; -- palette index width (palette table) - constant PPU_PALETTE_CIDX_WIDTH: natural := PPU_PALETTE_IDX_WIDTH + PPU_PALETTE_WIDTH; -- global palette index width - constant PPU_TMM_ADDR_WIDTH: natural := 16; - constant PPU_TMM_DATA_WIDTH: natural := 16; - constant PPU_BAM_ADDR_WIDTH: natural := 11; - constant PPU_BAM_DATA_WIDTH: natural := 15; - constant PPU_FAM_ADDR_WIDTH: natural := 8; - constant PPU_FAM_DATA_WIDTH: natural := 16; - constant PPU_PAL_ADDR_WIDTH: natural := 6; - constant PPU_PAL_DATA_WIDTH: natural := 12; - constant PPU_AUX_ADDR_WIDTH: natural := 2; - constant PPU_AUX_DATA_WIDTH: natural := 16; - constant PPU_POS_H_WIDTH: natural := 9; -- amount of bits for horizontal screen offset - constant PPU_POS_V_WIDTH: natural := 8; -- amount of bits for vertical screen offset -end package ppu_consts; + -- utility functions + function ceil_log2(n : natural) return natural; + constant PPU_RAM_BUS_ADDR_WIDTH : natural := 16; -- RAM bus address width + constant PPU_RAM_BUS_DATA_WIDTH : natural := 16; -- RAM bus data width + constant PPU_FG_SPRITE_COUNT : natural := 128; -- foreground sprites + constant PPU_COLOR_OUTPUT_DEPTH : natural := 4; -- VGA output channel depth + constant PPU_PALETTE_COLOR_WIDTH : natural := 3; -- palette index width (within sprite) + constant PPU_PALETTE_INDEX_WIDTH : natural := 3; -- palette index width (palette table) + constant PPU_PALETTE_CIDX_WIDTH : natural := (PPU_PALETTE_COLOR_WIDTH + PPU_PALETTE_INDEX_WIDTH); -- global palette index width + constant PPU_TMM_ADDR_WIDTH : natural := 16; -- tilemap memory ram bus address width + constant PPU_TMM_DATA_WIDTH : natural := 15; -- tilemap memory ram bus data width + constant PPU_BAM_ADDR_WIDTH : natural := 11; -- background attribute memory ram bus address width + constant PPU_BAM_DATA_WIDTH : natural := 15; -- background attribute memory ram bus data width + constant PPU_FAM_ADDR_WIDTH : natural := 8; -- foreground attribute memory ram bus address width + constant PPU_FAM_DATA_WIDTH : natural := 16; -- foreground attribute memory ram bus data width + constant PPU_PAL_ADDR_WIDTH : natural := 6; -- palette memory ram bus address width + constant PPU_PAL_DATA_WIDTH : natural := 12; -- palette memory ram bus data width + constant PPU_AUX_ADDR_WIDTH : natural := 1; -- auxiliary memory ram bus address width + constant PPU_AUX_DATA_WIDTH : natural := 16; -- auxiliary memory ram bus data width + constant PPU_POS_H_WIDTH : natural := 9; -- bits for horizontal screen offset + constant PPU_POS_V_WIDTH : natural := 8; -- bits for vertical screen offset + constant PPU_SPRITE_WIDTH : natural := 16; -- sprite width (pixels) + constant PPU_SPRITE_HEIGHT : natural := 16; -- sprite height (pixels) + constant PPU_SPRITE_PIDX_WIDTH : natural := 8; -- bits needed to identify horizontal and vertical pixel within sprite + constant PPU_SPRITE_POS_H_WIDTH: natural := 4; -- bits needed to identify horizontal pixel within sprite + constant PPU_SPRITE_POS_V_WIDTH: natural := 4; -- bits needed to identify vertical pixel within sprite + constant PPU_SCREEN_WIDTH : natural := 320; -- absolute screen width (pixels) + constant PPU_SCREEN_HEIGHT : natural := 240; -- absolute screen height (pixels) + constant PPU_BG_CANVAS_TILES_H : natural := 40; -- tiles (horizontally) on background canvas + constant PPU_BG_CANVAS_TILES_V : natural := 30; -- tiles (vertically) on background canvas + constant PPU_BG_CANVAS_TILE_H_WIDTH : natural := 6; -- bits needed to describe horizontal bg tile index (grid coordinates) + constant PPU_BG_CANVAS_TILE_V_WIDTH : natural := 5; -- bits needed to describe vertical bg tile index (grid coordinates) + constant PPU_TILE_INDEX_WIDTH : natural := 10; -- bits needed to index a tile from TMM memory + constant PPU_PIXELS_PER_TILE_WORD : natural := 5; -- pixels defined in one word in TMM memory + constant PPU_SPRITE_WORD_COUNT : natural := 52; -- words needed for a single sprite + constant PPU_PIXEL_BIT_WIDTH : natural := 3; -- bits needed to identify pixel in TMM word + constant PPU_TILE_BIT_WIDTH : natural := (PPU_SPRITE_WIDTH * PPU_SPRITE_HEIGHT * PPU_PALETTE_COLOR_WIDTH); -- bits in single tile + constant PPU_TMM_CACHE_FETCH_C_COUNT : natural := PPU_SPRITE_WORD_COUNT + 1; + constant PPU_TMM_CACHE_FETCH_A_COUNT : natural := PPU_TMM_CACHE_FETCH_C_COUNT * PPU_FG_SPRITE_COUNT; -- amount of clocks to fetch new TMM cache + constant PPU_TMM_CACHE_FETCH_A_WIDTH : natural := ceil_log2(PPU_TMM_CACHE_FETCH_A_COUNT); +end package ppu_consts; +package body ppu_consts is + -- https://stackoverflow.com/questions/21783280/number-of-bits-to-represent-an-integer-in-vhdl + -- Returns number of bits required to represent val in binary vector + function ceil_log2(n : natural) return natural is + begin + return natural(integer(ceil(log2(real(n - 1))))); + end function; +end package body ppu_consts; |