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CLK/Components/9918/Implementation/Fetch.hpp
Thomas Harte c9124f13cd Add suggested brackets.
2023-03-09 22:25:09 -05:00

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//
// Fetch.hpp
// Clock Signal
//
// Created by Thomas Harte on 01/01/2023.
// Copyright © 2023 Thomas Harte. All rights reserved.
//
#ifndef Fetch_hpp
#define Fetch_hpp
/*
Fetching routines follow below; they obey the following rules:
1) input is a start position and an end position; they should perform the proper
operations for the period: start <= time < end.
2) times are measured relative to a 172-cycles-per-line clock (so: they directly
count access windows on the TMS and Master System).
3) time 0 is the beginning of the access window immediately after the last pattern/data
block fetch that would contribute to this line, in a normal 32-column mode. So:
* it's cycle 309 on Mattias' TMS diagram;
* it's cycle 1238 on his V9938 diagram;
* it's after the last background render block in Mask of Destiny's Master System timing diagram.
That division point was selected, albeit arbitrarily, because it puts all the tile
fetches for a single line into the same [0, 171] period.
4) all of these functions are templated with a `use_end` parameter. That will be true if
end is < 172, false otherwise. So functions can use it to eliminate should-exit-not checks,
for the more usual path of execution.
Provided for the benefit of the methods below:
* the function external_slot(), which will perform any pending VRAM read/write.
* the macros slot(n) and external_slot(n) which can be used to schedule those things inside a
switch(start)-based implementation.
All functions should just spool data to intermediary storage. This is because for most VDPs there is
a decoupling between fetch pattern and output pattern, and it's neater to keep the same division
for the exceptions.
*/
// MARK: - Address mask helpers.
/// @returns An instance of @c AddressT with all top bits set down to and including
/// bit @c end and all others clear.
///
/// So e.g. if @c AddressT is @c uint16_t and this VDP has a 15-bit address space then
/// @c top_bits<10> will be the address with bits 15 to 10 (inclusive) set and the rest clear.
template <typename AddressT, int end> constexpr AddressT top_bits() {
return AddressT(~0) - AddressT((1 << end) - 1);
}
/// Modifies and returns @c source so that all bits above position @c n are set; the others are unmodified.
template <int n, typename AddressT> constexpr AddressT bits(AddressT source = 0) {
return AddressT(source | top_bits<AddressT, n>());
}
// MARK: - 171-window Dispatcher.
template <Personality personality>
template<bool use_end, typename SequencerT> void Base<personality>::dispatch(SequencerT &fetcher, int start, int end) {
#define index(n) \
if(use_end && end == n) return; \
[[fallthrough]]; \
case n: fetcher.template fetch<n>();
switch(start) {
default: assert(false);
index(0); index(1); index(2); index(3); index(4); index(5); index(6); index(7); index(8); index(9);
index(10); index(11); index(12); index(13); index(14); index(15); index(16); index(17); index(18); index(19);
index(20); index(21); index(22); index(23); index(24); index(25); index(26); index(27); index(28); index(29);
index(30); index(31); index(32); index(33); index(34); index(35); index(36); index(37); index(38); index(39);
index(40); index(41); index(42); index(43); index(44); index(45); index(46); index(47); index(48); index(49);
index(50); index(51); index(52); index(53); index(54); index(55); index(56); index(57); index(58); index(59);
index(60); index(61); index(62); index(63); index(64); index(65); index(66); index(67); index(68); index(69);
index(70); index(71); index(72); index(73); index(74); index(75); index(76); index(77); index(78); index(79);
index(80); index(81); index(82); index(83); index(84); index(85); index(86); index(87); index(88); index(89);
index(90); index(91); index(92); index(93); index(94); index(95); index(96); index(97); index(98); index(99);
index(100); index(101); index(102); index(103); index(104); index(105); index(106); index(107); index(108); index(109);
index(110); index(111); index(112); index(113); index(114); index(115); index(116); index(117); index(118); index(119);
index(120); index(121); index(122); index(123); index(124); index(125); index(126); index(127); index(128); index(129);
index(130); index(131); index(132); index(133); index(134); index(135); index(136); index(137); index(138); index(139);
index(140); index(141); index(142); index(143); index(144); index(145); index(146); index(147); index(148); index(149);
index(150); index(151); index(152); index(153); index(154); index(155); index(156); index(157); index(158); index(159);
index(160); index(161); index(162); index(163); index(164); index(165); index(166); index(167); index(168); index(169);
index(170);
}
#undef index
}
// MARK: - Fetchers.
template <Personality personality>
struct TextFetcher {
using AddressT = typename Base<personality>::AddressT;
TextFetcher(Base<personality> *base, LineBuffer &buffer, int y) :
base(base),
line_buffer(buffer),
row_base(base->pattern_name_address_ & bits<10>(AddressT((y >> 3) * 40))),
row_offset(base->pattern_generator_table_address_ & bits<11>(AddressT(y & 7))) {}
void fetch_name(AddressT column, int slot = 0) {
base->name_[slot] = base->ram_[row_base + column];
}
void fetch_pattern(AddressT column, int slot = 0) {
line_buffer.characters.shapes[column] = base->ram_[row_offset + size_t(base->name_[slot] << 3)];
}
Base<personality> *const base;
LineBuffer &line_buffer;
const AddressT row_base;
const AddressT row_offset;
};
template <Personality personality>
struct CharacterFetcher {
using AddressT = typename Base<personality>::AddressT;
CharacterFetcher(Base<personality> *base, LineBuffer &buffer, LineBuffer &sprite_selection_buffer, int y) :
base(base),
tile_buffer(buffer),
sprite_selection_buffer(sprite_selection_buffer),
y(y),
row_base(base->pattern_name_address_ & bits<10>(AddressT((y << 2)&~31)))
{
pattern_base = base->pattern_generator_table_address_;
colour_base = base->colour_table_address_;
colour_name_shift = 6;
if(buffer.screen_mode == ScreenMode::Graphics || buffer.screen_mode == ScreenMode::YamahaGraphics3) {
// If this is high resolution mode, allow the row number to affect the pattern and colour addresses.
pattern_base &= bits<13>(AddressT(((y & 0xc0) << 5)));
colour_base &= bits<13>(AddressT(((y & 0xc0) << 5)));
colour_base += AddressT(y & 7);
colour_name_shift = 0;
} else {
colour_base &= bits<6, AddressT>();
pattern_base &= bits<11, AddressT>();
}
if(buffer.screen_mode == ScreenMode::MultiColour) {
pattern_base += AddressT((y >> 2) & 7);
} else {
pattern_base += AddressT(y & 7);
}
}
void fetch_name(int column) {
base->tile_offset_ = base->ram_[row_base + AddressT(column)];
}
void fetch_pattern(int column) {
tile_buffer.tiles.patterns[column][0] = base->ram_[pattern_base + AddressT(base->tile_offset_ << 3)];
}
void fetch_colour(int column) {
tile_buffer.tiles.patterns[column][1] = base->ram_[colour_base + AddressT((base->tile_offset_ << 3) >> colour_name_shift)];
}
Base<personality> *const base;
LineBuffer &tile_buffer;
LineBuffer &sprite_selection_buffer;
const int y;
const AddressT row_base;
AddressT pattern_base;
AddressT colour_base;
int colour_name_shift;
};
constexpr SpriteMode sprite_mode(ScreenMode screen_mode) {
switch(screen_mode) {
default:
return SpriteMode::Mode2;
case ScreenMode::MultiColour:
case ScreenMode::ColouredText:
case ScreenMode::Graphics:
return SpriteMode::Mode1;
case ScreenMode::SMSMode4:
return SpriteMode::MasterSystem;
}
}
// TODO: should this be extended to include Master System sprites?
template <Personality personality, SpriteMode mode>
class SpriteFetcher {
public:
using AddressT = typename Base<personality>::AddressT;
// The Yamaha VDP adds an additional table when in Sprite Mode 2, the sprite colour
// table, which is intended to fill the 512 bytes before the programmer-located sprite
// attribute table.
//
// It partially enforces this proximity by forcing bits 7 and 8 to 0 in the address of
// the attribute table, and forcing them to 1 but masking out bit 9 for the colour table.
//
// AttributeAddressMask is used to enable or disable that behaviour.
static constexpr AddressT AttributeAddressMask = (mode == SpriteMode::Mode2) ? AddressT(~0x180) : AddressT(~0x000);
SpriteFetcher(Base<personality> *base, LineBuffer &buffer, LineBuffer &sprite_selection_buffer, int y) :
base(base),
tile_buffer(buffer),
sprite_selection_buffer(sprite_selection_buffer),
y(y) {}
void fetch_location(int slot) {
fetch_xy(slot);
if constexpr (mode == SpriteMode::Mode2) {
fetch_xy(slot + 1);
base->name_[0] = name(slot);
base->name_[1] = name(slot + 1);
}
}
void fetch_pattern(int slot) {
switch(mode) {
case SpriteMode::Mode1:
fetch_image(slot, name(slot));
break;
case SpriteMode::Mode2:
fetch_image(slot, base->name_[0]);
fetch_image(slot + 1, base->name_[1]);
break;
}
}
void fetch_y(int sprite) {
const AddressT address = base->sprite_attribute_table_address_ & AttributeAddressMask & bits<7>(AddressT(sprite << 2));
const uint8_t sprite_y = base->ram_[address];
base->posit_sprite(sprite_selection_buffer, sprite, sprite_y, y);
}
private:
void fetch_xy(int slot) {
tile_buffer.active_sprites[slot].x =
base->ram_[
base->sprite_attribute_table_address_ & AttributeAddressMask & bits<7>(AddressT((tile_buffer.active_sprites[slot].index << 2) | 1))
];
}
uint8_t name(int slot) {
const AddressT address =
base->sprite_attribute_table_address_ &
AttributeAddressMask &
bits<7>(AddressT((tile_buffer.active_sprites[slot].index << 2) | 2));
const uint8_t name = base->ram_[address] & (base->sprites_16x16_ ? ~3 : ~0);
return name;
}
void fetch_image(int slot, uint8_t name) {
uint8_t colour = 0;
auto &sprite = tile_buffer.active_sprites[slot];
switch(mode) {
case SpriteMode::Mode1:
// Fetch colour from the attribute table, per this sprite's slot.
colour = base->ram_[
base->sprite_attribute_table_address_ & bits<7>(AddressT((sprite.index << 2) | 3))
];
break;
case SpriteMode::Mode2: {
// Fetch colour from the colour table, per this sprite's slot and row.
const AddressT colour_table_address = (base->sprite_attribute_table_address_ | ~AttributeAddressMask) & AddressT(~0x200);
colour = base->ram_[
colour_table_address &
bits<9>(
AddressT(sprite.index << 4) |
AddressT(sprite.row)
)
];
} break;
}
sprite.image[2] = colour;
sprite.x -= sprite.early_clock();
const AddressT graphic_location = base->sprite_generator_table_address_ & bits<11>(AddressT((name << 3) | sprite.row));
sprite.image[0] = base->ram_[graphic_location];
sprite.image[1] = base->ram_[graphic_location+16];
}
Base<personality> *const base;
LineBuffer &tile_buffer;
LineBuffer &sprite_selection_buffer;
const int y;
};
template <Personality personality>
struct SMSFetcher {
using AddressT = typename Base<personality>::AddressT;
struct RowInfo {
AddressT pattern_address_base;
AddressT sub_row[2];
};
SMSFetcher(Base<personality> *base, LineBuffer &buffer, LineBuffer &sprite_selection_buffer, int y) :
base(base),
storage(static_cast<Storage<personality> *>(base)),
tile_buffer(buffer),
sprite_selection_buffer(sprite_selection_buffer),
y(y),
horizontal_offset((y >= 16 || !storage->horizontal_scroll_lock_) ? (tile_buffer.latched_horizontal_scroll >> 3) : 0)
{
// Limit address bits in use if this is a SMS2 mode.
const bool is_tall_mode = base->mode_timing_.pixel_lines != 192;
const AddressT pattern_name_address = storage->pattern_name_address_ | (is_tall_mode ? 0x800 : 0);
const AddressT pattern_name_offset = is_tall_mode ? 0x100 : 0;
// Determine row info for the screen both (i) if vertical scrolling is applied; and (ii) if it isn't.
// The programmer can opt out of applying vertical scrolling to the right-hand portion of the display.
const int scrolled_row = (y + storage->latched_vertical_scroll_) % (is_tall_mode ? 256 : 224);
scrolled_row_info.pattern_address_base = (pattern_name_address & bits<11>(AddressT((scrolled_row & ~7) << 3))) - pattern_name_offset;
scrolled_row_info.sub_row[0] = AddressT((scrolled_row & 7) << 2);
scrolled_row_info.sub_row[1] = AddressT(28 ^ ((scrolled_row & 7) << 2));
if(storage->vertical_scroll_lock_) {
static_row_info.pattern_address_base = bits<11>(AddressT(pattern_name_address & ((y & ~7) << 3))) - pattern_name_offset;
static_row_info.sub_row[0] = AddressT((y & 7) << 2);
static_row_info.sub_row[1] = 28 ^ AddressT((y & 7) << 2);
} else static_row_info = scrolled_row_info;
}
void fetch_sprite(int sprite) {
tile_buffer.active_sprites[sprite].x =
base->ram_[
storage->sprite_attribute_table_address_ & bits<7>((tile_buffer.active_sprites[sprite].index << 1) | 0)
] - (storage->shift_sprites_8px_left_ ? 8 : 0);
const uint8_t name = base->ram_[
storage->sprite_attribute_table_address_ & bits<7>((tile_buffer.active_sprites[sprite].index << 1) | 1)
] & (base->sprites_16x16_ ? ~1 : ~0);
const AddressT graphic_location =
storage->sprite_generator_table_address_ &
bits<13>(AddressT((name << 5) | (tile_buffer.active_sprites[sprite].row << 2)));
tile_buffer.active_sprites[sprite].image[0] = base->ram_[graphic_location];
tile_buffer.active_sprites[sprite].image[1] = base->ram_[graphic_location+1];
tile_buffer.active_sprites[sprite].image[2] = base->ram_[graphic_location+2];
tile_buffer.active_sprites[sprite].image[3] = base->ram_[graphic_location+3];
}
void fetch_tile_name(int column) {
const RowInfo &row_info = column < 24 ? scrolled_row_info : static_row_info;
const size_t scrolled_column = (column - horizontal_offset) & 0x1f;
const size_t address = row_info.pattern_address_base + (scrolled_column << 1);
tile_buffer.tiles.flags[column] = base->ram_[address+1];
base->tile_offset_ = AddressT(
(((tile_buffer.tiles.flags[column]&1) << 8) | base->ram_[address]) << 5
) + row_info.sub_row[(tile_buffer.tiles.flags[column]&4) >> 2];
}
void fetch_tile_pattern(int column) {
tile_buffer.tiles.patterns[column][0] = base->ram_[base->tile_offset_];
tile_buffer.tiles.patterns[column][1] = base->ram_[base->tile_offset_+1];
tile_buffer.tiles.patterns[column][2] = base->ram_[base->tile_offset_+2];
tile_buffer.tiles.patterns[column][3] = base->ram_[base->tile_offset_+3];
}
void posit_sprite(int sprite) {
base->posit_sprite(sprite_selection_buffer, sprite, base->ram_[storage->sprite_attribute_table_address_ & bits<8>(AddressT(sprite))], y);
}
Base<personality> *const base;
const Storage<personality> *const storage;
LineBuffer &tile_buffer;
LineBuffer &sprite_selection_buffer;
const int y;
const int horizontal_offset;
RowInfo scrolled_row_info, static_row_info;
};
// MARK: - TMS Sequencers.
template <Personality personality>
struct RefreshSequencer {
RefreshSequencer(Base<personality> *base) : base(base) {}
template <int cycle> void fetch() {
if(cycle < 44 || (cycle&1)) {
base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(cycle));
}
}
Base<personality> *const base;
};
template <Personality personality>
struct TextSequencer {
template <typename... Args> TextSequencer(Args&&... args) : fetcher(std::forward<Args>(args)...) {}
template <int cycle> void fetch() {
// The first 47 and the final 4 slots are external.
if constexpr (cycle < 47 || cycle >= 167) {
fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(cycle));
return;
} else {
// For the 120 slots in between follow a three-step pattern of:
constexpr int offset = cycle - 47;
constexpr auto column = AddressT(offset / 3);
switch(offset % 3) {
case 0: fetcher.fetch_name(column); break; // (1) fetch tile name.
case 1: fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(cycle)); break; // (2) external slot.
case 2: fetcher.fetch_pattern(column); break; // (3) fetch tile pattern.
}
}
}
using AddressT = typename Base<personality>::AddressT;
TextFetcher<personality> fetcher;
};
template <Personality personality>
struct CharacterSequencer {
template <typename... Args> CharacterSequencer(Args&&... args) :
character_fetcher(std::forward<Args>(args)...),
sprite_fetcher(std::forward<Args>(args)...) {}
template <int cycle> void fetch() {
if(cycle < 2) {
character_fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(cycle));
}
if(cycle == 2) {
// Fetch: y0, x0, n0, c0, pat0a, pat0b, y1, x1, n1, c1, pat1a, pat1b, y2, x2.
sprite_fetcher.fetch_location(0);
sprite_fetcher.fetch_pattern(0);
sprite_fetcher.fetch_location(1);
sprite_fetcher.fetch_pattern(1);
sprite_fetcher.fetch_location(2);
}
if(cycle > 16 && cycle < 21) {
character_fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(cycle));
}
if(cycle == 21) {
// Fetch: n1, c2, pat2a, pat2b, y3, x3, n3, c3, pat3a, pat3b.
sprite_fetcher.fetch_pattern(2);
sprite_fetcher.fetch_location(3);
sprite_fetcher.fetch_pattern(3);
}
if(cycle >= 31 && cycle < 35) {
character_fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(cycle));
}
// Cycles 35 to 43: fetch 8 new sprite Y coordinates, to begin selecting sprites for next line.
if(cycle == 35) {
sprite_fetcher.fetch_y(0); sprite_fetcher.fetch_y(1); sprite_fetcher.fetch_y(2); sprite_fetcher.fetch_y(3);
sprite_fetcher.fetch_y(4); sprite_fetcher.fetch_y(5); sprite_fetcher.fetch_y(6); sprite_fetcher.fetch_y(7);
}
// Rest of line: tiles themselves, plus some additional potential sprites.
if(cycle >= 43) {
constexpr int offset = cycle - 43;
constexpr int block = offset >> 2;
constexpr int sub_block = offset & 3;
switch(sub_block) {
case 0: character_fetcher.fetch_name(block); break;
case 1:
if(!(block & 3)) {
character_fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(cycle));
} else {
constexpr int sprite = 8 + ((block >> 2) * 3) + ((block & 3) - 1);
sprite_fetcher.fetch_y(sprite);
}
break;
case 3:
character_fetcher.fetch_pattern(block);
character_fetcher.fetch_pattern(block);
break;
default: break;
}
}
}
using AddressT = typename Base<personality>::AddressT;
CharacterFetcher<personality> character_fetcher;
SpriteFetcher<personality, SpriteMode::Mode1> sprite_fetcher;
};
// MARK: - TMS fetch routines.
template <Personality personality>
template<bool use_end> void Base<personality>::fetch_tms_refresh(LineBuffer &, LineBuffer &, int, int start, int end) {
RefreshSequencer sequencer(this);
dispatch<use_end>(sequencer, start, end);
}
template <Personality personality>
template<bool use_end> void Base<personality>::fetch_tms_text(LineBuffer &line_buffer, LineBuffer &, int y, int start, int end) {
TextSequencer<personality> sequencer(this, line_buffer, y);
dispatch<use_end>(sequencer, start, end);
}
template <Personality personality>
template<bool use_end> void Base<personality>::fetch_tms_character(LineBuffer &line_buffer, LineBuffer &next_line_buffer, int y, int start, int end) {
CharacterSequencer<personality> sequencer(this, line_buffer, next_line_buffer, y);
dispatch<use_end>(sequencer, start, end);
}
// MARK: - Master System
template <Personality personality>
struct SMSSequencer {
template <typename... Args> SMSSequencer(Args&&... args) : fetcher(std::forward<Args>(args)...) {}
template <int cycle> void fetch() {
if(!cycle) {
fetcher.fetch_sprite(0);
fetcher.fetch_sprite(1);
fetcher.fetch_sprite(2);
fetcher.fetch_sprite(3);
}
if(cycle >= 12 && cycle < 17) {
fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(cycle));
}
if(cycle == 17) {
fetcher.fetch_sprite(4);
fetcher.fetch_sprite(5);
fetcher.fetch_sprite(6);
fetcher.fetch_sprite(7);
}
if(cycle == 29 || cycle == 30) {
fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(cycle));
}
if(cycle == 31) {
fetcher.posit_sprite(0); fetcher.posit_sprite(1); fetcher.posit_sprite(2); fetcher.posit_sprite(3);
fetcher.posit_sprite(4); fetcher.posit_sprite(5); fetcher.posit_sprite(6); fetcher.posit_sprite(7);
fetcher.posit_sprite(8); fetcher.posit_sprite(9); fetcher.posit_sprite(10); fetcher.posit_sprite(11);
fetcher.posit_sprite(12); fetcher.posit_sprite(13); fetcher.posit_sprite(14); fetcher.posit_sprite(15);
}
if(cycle >= 39 && cycle < 167) {
constexpr int offset = cycle - 39;
constexpr int block = offset >> 2;
constexpr int sub_block = offset & 3;
switch(sub_block) {
default: break;
case 0: fetcher.fetch_tile_name(block); break;
case 1:
if(!(block & 3)) {
fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(cycle));
} else {
constexpr int sprite = (8 + ((block >> 2) * 3) + ((block & 3) - 1)) << 1;
fetcher.posit_sprite(sprite);
fetcher.posit_sprite(sprite+1);
}
break;
case 2: fetcher.fetch_tile_pattern(block); break;
}
}
if(cycle >= 167) {
fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(cycle));
}
}
using AddressT = typename Base<personality>::AddressT;
SMSFetcher<personality> fetcher;
};
template <Personality personality>
template<bool use_end> void Base<personality>::fetch_sms(LineBuffer &line_buffer, LineBuffer &next_line_buffer, int y, int start, int end) {
if constexpr (is_sega_vdp(personality)) {
SMSSequencer<personality> sequencer(this, line_buffer, next_line_buffer, y);
dispatch<use_end>(sequencer, start, end);
}
}
// MARK: - Yamaha
template <Personality personality>
template<ScreenMode mode> void Base<personality>::fetch_yamaha(LineBuffer &line_buffer, LineBuffer &next_line_buffer, int y, int end) {
CharacterFetcher character_fetcher(this, line_buffer, next_line_buffer, y);
TextFetcher text_fetcher(this, line_buffer, y);
SpriteFetcher<personality, sprite_mode(mode)> sprite_fetcher(this, line_buffer, next_line_buffer, y);
using Type = typename Storage<personality>::Event::Type;
while(Storage<personality>::next_event_->offset < end) {
switch(Storage<personality>::next_event_->type) {
case Type::External:
do_external_slot(Storage<personality>::next_event_->offset);
break;
case Type::Name:
switch(mode) {
case ScreenMode::Text: {
const auto column = AddressT(Storage<personality>::next_event_->id << 1);
text_fetcher.fetch_name(column, 0);
text_fetcher.fetch_name(column + 1, 1);
} break;
case ScreenMode::YamahaText80: {
const auto column = AddressT(Storage<personality>::next_event_->id << 2);
const auto start = pattern_name_address_ & bits<12>(AddressT((y >> 3) * 80));
name_[0] = ram_[start + column + 0];
name_[1] = ram_[start + column + 1];
name_[2] = ram_[start + column + 2];
name_[3] = ram_[start + column + 3];
} break;
case ScreenMode::Graphics:
case ScreenMode::MultiColour:
case ScreenMode::ColouredText:
character_fetcher.fetch_name(Storage<personality>::next_event_->id);
break;
default: break;
}
break;
case Type::Colour:
switch(mode) {
case ScreenMode::YamahaText80: {
const auto column = AddressT(Storage<personality>::next_event_->id);
const auto address = colour_table_address_ & bits<9>(AddressT((y >> 3) * 10));
line_buffer.characters.flags[column] = ram_[address + column];
} break;
case ScreenMode::Graphics:
case ScreenMode::MultiColour:
case ScreenMode::ColouredText:
character_fetcher.fetch_colour(Storage<personality>::next_event_->id);
break;
default: break;
}
break;
case Type::Pattern:
switch(mode) {
case ScreenMode::Text: {
const auto column = AddressT(Storage<personality>::next_event_->id << 1);
text_fetcher.fetch_pattern(column, 0);
text_fetcher.fetch_pattern(column + 1, 1);
} break;
case ScreenMode::YamahaText80: {
const auto column = Storage<personality>::next_event_->id << 2;
const auto start = pattern_generator_table_address_ & bits<11>(AddressT(y & 7));
line_buffer.characters.shapes[column + 0] = ram_[start + AddressT(name_[0] << 3)];
line_buffer.characters.shapes[column + 1] = ram_[start + AddressT(name_[1] << 3)];
line_buffer.characters.shapes[column + 2] = ram_[start + AddressT(name_[2] << 3)];
line_buffer.characters.shapes[column + 3] = ram_[start + AddressT(name_[3] << 3)];
} break;
case ScreenMode::Graphics:
case ScreenMode::MultiColour:
case ScreenMode::ColouredText:
character_fetcher.fetch_pattern(Storage<personality>::next_event_->id);
break;
case ScreenMode::YamahaGraphics3:
// As per comment elsewhere; my _guess_ is that G3 is slotted as if it were
// a bitmap mode, with the three bytes that describe each column fitting into
// the relevant windows.
character_fetcher.fetch_name(Storage<personality>::next_event_->id);
character_fetcher.fetch_colour(Storage<personality>::next_event_->id);
character_fetcher.fetch_pattern(Storage<personality>::next_event_->id);
break;
case ScreenMode::YamahaGraphics4:
case ScreenMode::YamahaGraphics5: {
const int column = Storage<personality>::next_event_->id << 2;
const auto start = bits<15>((y << 7) | column);
line_buffer.bitmap[column + 0] = ram_[pattern_name_address_ & AddressT(start + 0)];
line_buffer.bitmap[column + 1] = ram_[pattern_name_address_ & AddressT(start + 1)];
line_buffer.bitmap[column + 2] = ram_[pattern_name_address_ & AddressT(start + 2)];
line_buffer.bitmap[column + 3] = ram_[pattern_name_address_ & AddressT(start + 3)];
} break;
case ScreenMode::YamahaGraphics6:
case ScreenMode::YamahaGraphics7: {
const uint8_t *const ram2 = &ram_[65536];
const int column = Storage<personality>::next_event_->id << 3;
const auto start = bits<15>((y << 7) | (column >> 1));
// Fetch from alternate banks.
line_buffer.bitmap[column + 0] = ram_[pattern_name_address_ & AddressT(start + 0) & 0xffff];
line_buffer.bitmap[column + 1] = ram2[pattern_name_address_ & AddressT(start + 0) & 0xffff];
line_buffer.bitmap[column + 2] = ram_[pattern_name_address_ & AddressT(start + 1) & 0xffff];
line_buffer.bitmap[column + 3] = ram2[pattern_name_address_ & AddressT(start + 1) & 0xffff];
line_buffer.bitmap[column + 4] = ram_[pattern_name_address_ & AddressT(start + 2) & 0xffff];
line_buffer.bitmap[column + 5] = ram2[pattern_name_address_ & AddressT(start + 2) & 0xffff];
line_buffer.bitmap[column + 6] = ram_[pattern_name_address_ & AddressT(start + 3) & 0xffff];
line_buffer.bitmap[column + 7] = ram2[pattern_name_address_ & AddressT(start + 3) & 0xffff];
} break;
default: break;
}
break;
case Type::SpriteY:
switch(mode) {
case ScreenMode::Blank:
case ScreenMode::Text:
case ScreenMode::YamahaText80:
// Ensure the compiler can discard character_fetcher in these modes.
break;
default:
sprite_fetcher.fetch_y(Storage<personality>::next_event_->id);
break;
}
break;
case Type::SpriteLocation:
switch(mode) {
case ScreenMode::Blank:
case ScreenMode::Text:
case ScreenMode::YamahaText80:
// Ensure the compiler can discard character_fetcher in these modes.
break;
default:
sprite_fetcher.fetch_location(Storage<personality>::next_event_->id);
break;
}
break;
case Type::SpritePattern:
switch(mode) {
case ScreenMode::Blank:
case ScreenMode::Text:
case ScreenMode::YamahaText80:
// Ensure the compiler can discard character_fetcher in these modes.
break;
default:
sprite_fetcher.fetch_pattern(Storage<personality>::next_event_->id);
break;
}
break;
default: break;
}
++Storage<personality>::next_event_;
}
}
template <Personality personality>
template<bool use_end> void Base<personality>::fetch_yamaha(LineBuffer &line_buffer, LineBuffer &next_line_buffer, int y, int, int end) {
if constexpr (is_yamaha_vdp(personality)) {
// Dispatch according to [supported] screen mode.
#define Dispatch(mode) case mode: fetch_yamaha<mode>(line_buffer, next_line_buffer, y, end); break;
switch(line_buffer.screen_mode) {
default: break;
Dispatch(ScreenMode::Blank);
Dispatch(ScreenMode::Text);
Dispatch(ScreenMode::MultiColour);
Dispatch(ScreenMode::ColouredText);
Dispatch(ScreenMode::Graphics);
Dispatch(ScreenMode::YamahaText80);
Dispatch(ScreenMode::YamahaGraphics3);
Dispatch(ScreenMode::YamahaGraphics4);
Dispatch(ScreenMode::YamahaGraphics5);
Dispatch(ScreenMode::YamahaGraphics6);
Dispatch(ScreenMode::YamahaGraphics7);
}
#undef Dispatch
}
}
// MARK: - Mega Drive
// TODO.
#endif /* Fetch_hpp */
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