diff options
Diffstat (limited to 'lib/nes/ppu.hh')
| -rw-r--r-- | lib/nes/ppu.hh | 88 |
1 files changed, 69 insertions, 19 deletions
diff --git a/lib/nes/ppu.hh b/lib/nes/ppu.hh index d58bfd4..4f15d37 100644 --- a/lib/nes/ppu.hh +++ b/lib/nes/ppu.hh @@ -20,26 +20,19 @@ namespace nes // Writes to some registers are ignored until this clock cycle. static constexpr auto boot_up_cycles = cycle_count::from_ppu(29658); - enum class role : unsigned - { - background = 0, - sprite = 1, - }; - enum class color : std::uint8_t { }; struct color_index { - auto get_color() const -> unsigned { return (value & 0b00000011u) >> 0; } - auto get_palette() const -> unsigned { return (value & 0b00001100u) >> 2; } - auto get_role() const -> role { return role{ (value & 0b00010000u) >> 4 }; } + auto get_color() const -> unsigned { return (value & 0b00000011) >> 0; } + auto get_palette() const -> unsigned { return (value & 0b00001100) >> 2; } + auto get_foreground() const -> bool { return value & 0b00010000; } auto set_color(unsigned const v) -> void { value = (value & ~0b00000011) | ((v << 0) & 0b00000011); } auto set_palette(unsigned const v) -> void { value = (value & ~0b00001100) | ((v << 2) & 0b00001100); } - auto set_role(unsigned const v) -> void { value = (value & ~0b00010000) | ((v << 4) & 0b00010000); } - auto set_role(role const v) -> void { set_role(static_cast<unsigned>(v)); } + auto set_foreground(bool const v) -> void { value = (value & ~0b00010000) | (v ? 0b00010000 : 0); } std::uint8_t value{}; @@ -51,8 +44,42 @@ namespace nes struct sprite { + // Tile index and pattern table for large sprites + auto get_pattern_table() const -> unsigned { return (tile_index & 0b00000001) >> 0; } + auto get_top_tile() const -> unsigned { return (tile_index & 0b11111110) >> 1; } + + auto set_pattern_table(unsigned const v) -> void { tile_index = (tile_index & ~0b00000001) | ((v << 0) & 0b00000001); } + auto set_top_tile(unsigned const v) -> void { tile_index = (tile_index & ~0b11111110) | ((v << 1) & 0b11111110); } + + // Attributes + auto get_palette() const -> unsigned { return (attributes & 0b00000011) >> 0; } + auto get_behind_background() const -> bool { return attributes & 0b00100000; } + auto get_flip_horizontal() const -> bool { return attributes & 0b01000000; } + auto get_flip_vertical() const -> bool { return attributes & 0b10000000; } + + auto set_palette(unsigned const v) -> void { attributes = (attributes & ~0b00000011) | ((v << 0) & 0b00000011); } + auto set_behind_background(bool const v) -> void { attributes = (attributes & ~0b00100000) | (v ? 0b00100000 : 0); } + auto set_flip_horizontal(bool const v) -> void { attributes = (attributes & ~0b01000000) | (v ? 0b01000000 : 0); } + auto set_flip_vertical(bool const v) -> void { attributes = (attributes & ~0b10000000) | (v ? 0b10000000 : 0); } + + std::uint8_t y{}; + std::uint8_t tile_index{}; + std::uint8_t attributes{}; + std::uint8_t x{}; + + explicit sprite(std::uint8_t const y, std::uint8_t const tile_index, std::uint8_t const attributes, std::uint8_t const x) + : y{ y } + , tile_index{ tile_index } + , attributes{ attributes } + , x{ x } + { + } + }; + + struct evaluated_sprite + { std::uint32_t pattern{ 0 }; - std::uint8_t position{ 0 }; + std::uint8_t x{ 0 }; bool is_in_front{ false }; bool is_sprite_zero{ false }; }; @@ -147,8 +174,30 @@ namespace nes struct { // See https://www.nesdev.org/wiki/PPU_scrolling#PPU_internal_registers - std::uint16_t v{}; // Current VRAM address (15 bits) - std::uint16_t t{}; // Temporary VRAM address (15 bits) + struct + { + // Scroll position + auto get_coarse_x() const -> unsigned { return (value & 0b0000000000011111) >> 0; } + auto get_coarse_y() const -> unsigned { return (value & 0b0000001111100000) >> 5; } + auto get_horizontal_name_table() const -> unsigned { return (value & 0b0000010000000000) >> 10; } + auto get_vertical_name_table() const -> unsigned { return (value & 0b0000100000000000) >> 11; } + auto get_fine_y() const -> unsigned { return (value & 0b0111000000000000) >> 12; } + + auto set_coarse_x(unsigned const v) -> void { value = (value & ~0b0000000000011111) | ((v << 0) & 0b0000000000011111); } + auto set_coarse_y(unsigned const v) -> void { value = (value & ~0b0000001111100000) | ((v << 5) & 0b0000001111100000); } + auto set_horizontal_name_table(unsigned const v) -> void { value = (value & ~0b0000010000000000) | ((v << 10) & 0b0000010000000000); } + auto set_vertical_name_table(unsigned const v) -> void { value = (value & ~0b0000100000000000) | ((v << 11) & 0b0000100000000000); } + auto set_fine_y(unsigned const v) -> void { value = (value & ~0b0111000000000000) | ((v << 12) & 0b0111000000000000); } + + // Address + auto get_address_low() const -> unsigned { return (value & 0b0000000011111111) >> 0; } + auto get_address_high() const -> unsigned { return (value & 0b0111111100000000) >> 8; } + + auto set_address_low(unsigned const v) -> void { value = (value & ~0b0000000011111111) | ((v << 0) & 0b0000000011111111); } + auto set_address_high(unsigned const v) -> void { value = (value & ~0b0111111100000000) | ((v << 8) & 0b0111111100000000); } + + std::uint16_t value{}; + } v{}, t{}; // Current and temporary VRAM address and scroll position (15 bits) std::uint8_t x{}; // Fine X scroll (3 bits) bool w{}; // Second write toggle (1 bit) } internal_{}; @@ -162,7 +211,7 @@ namespace nes std::uint8_t attribute_table_byte_{ 0 }; std::uint8_t low_tile_byte_{ 0 }; std::uint8_t high_tile_byte_{ 0 }; - sprite sprites_[8]{}; // Evaluated sprites. + evaluated_sprite sprites_[8]{}; // Evaluated sprites. unsigned sprite_count_{ 0 }; // Number of evaluated sprites in sprites_. public: @@ -211,13 +260,14 @@ namespace nes auto copy_x() -> void; auto copy_y() -> void; auto evaluate_sprites() -> void; - auto fetch_sprite_pattern(unsigned i, unsigned row) -> std::uint32_t; + auto fetch_sprite_pattern(sprite, unsigned row) -> std::uint32_t; // Helpers - auto sprite_height() -> unsigned; + auto sprite_height() const -> unsigned; auto increment_vram() -> void; - auto get_color(color_index) -> color&; - auto resolve_color(color) -> rgb; + auto get_sprite(unsigned) const -> sprite; + auto ref_color(color_index) -> color&; + auto resolve_color(color) const -> rgb; }; } // namespace nes
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