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514 lines
17 KiB
C++
514 lines
17 KiB
C++
//
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// Fetch.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 01/01/2023.
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// Copyright © 2023 Thomas Harte. All rights reserved.
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//
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#ifndef Fetch_hpp
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#define Fetch_hpp
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/*
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Fetching routines follow below; they obey the following rules:
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1) input is a start position and an end position; they should perform the proper
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operations for the period: start <= time < end.
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2) times are measured relative to a 172-cycles-per-line clock (so: they directly
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count access windows on the TMS and Master System).
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3) time 0 is the beginning of the access window immediately after the last pattern/data
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block fetch that would contribute to this line, in a normal 32-column mode. So:
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* it's cycle 309 on Mattias' TMS diagram;
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* it's cycle 1238 on his V9938 diagram;
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* it's after the last background render block in Mask of Destiny's Master System timing diagram.
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That division point was selected, albeit arbitrarily, because it puts all the tile
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fetches for a single line into the same [0, 171] period.
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4) all of these functions are templated with a `use_end` parameter. That will be true if
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end is < 172, false otherwise. So functions can use it to eliminate should-exit-not checks,
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for the more usual path of execution.
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Provided for the benefit of the methods below:
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* the function external_slot(), which will perform any pending VRAM read/write.
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* the macros slot(n) and external_slot(n) which can be used to schedule those things inside a
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switch(start)-based implementation.
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All functions should just spool data to intermediary storage. This is because for most VDPs there is
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a decoupling between fetch pattern and output pattern, and it's neater to keep the same division
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for the exceptions.
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*/
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#define slot(n) \
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if(use_end && end == n) return; \
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[[fallthrough]]; \
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case n
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#define external_slot(n) \
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slot(n): do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(n));
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#define external_slots_2(n) \
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external_slot(n); \
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external_slot(n+1);
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#define external_slots_4(n) \
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external_slots_2(n); \
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external_slots_2(n+2);
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#define external_slots_8(n) \
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external_slots_4(n); \
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external_slots_4(n+4);
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#define external_slots_16(n) \
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external_slots_8(n); \
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external_slots_8(n+8);
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#define external_slots_32(n) \
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external_slots_16(n); \
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external_slots_16(n+16);
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// MARK: - TMS9918
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template <Personality personality>
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template<bool use_end> void Base<personality>::fetch_tms_refresh(int start, int end) {
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#define refresh(location) \
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slot(location): \
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external_slot(location+1);
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#define refreshes_2(location) \
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refresh(location); \
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refresh(location+2);
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#define refreshes_4(location) \
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refreshes_2(location); \
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refreshes_2(location+4);
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#define refreshes_8(location) \
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refreshes_4(location); \
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refreshes_4(location+8);
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switch(start) {
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default: assert(false);
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/* 44 external slots */
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external_slots_32(0)
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external_slots_8(32)
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external_slots_4(40)
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/* 64 refresh/external slot pairs (= 128 windows) */
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refreshes_8(44);
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refreshes_8(60);
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refreshes_8(76);
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refreshes_8(92);
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refreshes_8(108);
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refreshes_8(124);
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refreshes_8(140);
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refreshes_8(156);
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return;
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}
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#undef refreshes_8
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#undef refreshes_4
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#undef refreshes_2
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#undef refresh
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}
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template <Personality personality>
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template<bool use_end> void Base<personality>::fetch_tms_text(int start, int end) {
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#define fetch_tile_name(location, column) slot(location): line_buffer.names[column].offset = ram_[row_base + column];
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#define fetch_tile_pattern(location, column) slot(location): line_buffer.patterns[column][0] = ram_[row_offset + size_t(line_buffer.names[column].offset << 3)];
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#define fetch_column(location, column) \
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fetch_tile_name(location, column); \
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external_slot(location+1); \
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fetch_tile_pattern(location+2, column);
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#define fetch_columns_2(location, column) \
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fetch_column(location, column); \
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fetch_column(location+3, column+1);
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#define fetch_columns_4(location, column) \
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fetch_columns_2(location, column); \
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fetch_columns_2(location+6, column+2);
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#define fetch_columns_8(location, column) \
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fetch_columns_4(location, column); \
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fetch_columns_4(location+12, column+4);
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LineBuffer &line_buffer = line_buffers_[fetch_pointer_.row];
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const size_t row_base = pattern_name_address_ & (0x3c00 | size_t(fetch_pointer_.row >> 3) * 40);
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const size_t row_offset = pattern_generator_table_address_ & (0x3800 | (fetch_pointer_.row & 7));
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switch(start) {
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default: assert(false);
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/* 47 external slots (= 47 windows) */
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external_slots_32(0)
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external_slots_8(32)
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external_slots_4(40)
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external_slots_2(44)
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external_slot(46)
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/* 40 column fetches (= 120 windows) */
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fetch_columns_8(47, 0);
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fetch_columns_8(71, 8);
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fetch_columns_8(95, 16);
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fetch_columns_8(119, 24);
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fetch_columns_8(143, 32);
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/* 5 more external slots */
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external_slots_4(167);
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external_slot(171);
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return;
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}
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#undef fetch_columns_8
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#undef fetch_columns_4
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#undef fetch_columns_2
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#undef fetch_column
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#undef fetch_tile_pattern
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#undef fetch_tile_name
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}
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template <Personality personality>
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template<bool use_end> void Base<personality>::fetch_tms_character(int start, int end) {
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#define sprite_fetch_coordinates(location, sprite) \
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slot(location): \
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slot(location+1): \
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line_buffer.active_sprites[sprite].x = \
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ram_[\
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sprite_attribute_table_address_ & size_t(0x3f81 | (line_buffer.active_sprites[sprite].index << 2))\
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];
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// This implementation doesn't refetch Y; it's unclear to me
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// whether it's refetched.
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#define sprite_fetch_graphics(location, sprite) \
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slot(location): \
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slot(location+1): \
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slot(location+2): \
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slot(location+3): {\
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const uint8_t name = ram_[\
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sprite_attribute_table_address_ & size_t(0x3f82 | (line_buffer.active_sprites[sprite].index << 2))\
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] & (sprites_16x16_ ? ~3 : ~0);\
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line_buffer.active_sprites[sprite].image[2] = ram_[\
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sprite_attribute_table_address_ & size_t(0x3f83 | (line_buffer.active_sprites[sprite].index << 2))\
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];\
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line_buffer.active_sprites[sprite].x -= (line_buffer.active_sprites[sprite].image[2] & 0x80) >> 2;\
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const size_t graphic_location = sprite_generator_table_address_ & size_t(0x3800 | (name << 3) | line_buffer.active_sprites[sprite].row); \
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line_buffer.active_sprites[sprite].image[0] = ram_[graphic_location];\
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line_buffer.active_sprites[sprite].image[1] = ram_[graphic_location+16];\
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}
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#define sprite_fetch_block(location, sprite) \
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sprite_fetch_coordinates(location, sprite) \
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sprite_fetch_graphics(location+2, sprite)
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#define sprite_y_read(location, sprite) \
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slot(location): posit_sprite(sprite_selection_buffer, sprite, ram_[sprite_attribute_table_address_ & (((sprite) << 2) | 0x3f80)], fetch_pointer_.row);
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#define fetch_tile_name(column) line_buffer.names[column].offset = ram_[(row_base + column) & 0x3fff];
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#define fetch_tile(column) {\
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line_buffer.patterns[column][1] = ram_[(colour_base + size_t((line_buffer.names[column].offset << 3) >> colour_name_shift)) & 0x3fff]; \
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line_buffer.patterns[column][0] = ram_[(pattern_base + size_t(line_buffer.names[column].offset << 3)) & 0x3fff]; \
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}
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#define background_fetch_block(location, column, sprite) \
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slot(location): fetch_tile_name(column) \
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external_slot(location+1); \
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slot(location+2): \
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slot(location+3): fetch_tile(column) \
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slot(location+4): fetch_tile_name(column+1) \
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sprite_y_read(location+5, sprite); \
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slot(location+6): \
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slot(location+7): fetch_tile(column+1) \
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slot(location+8): fetch_tile_name(column+2) \
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sprite_y_read(location+9, sprite+1); \
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slot(location+10): \
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slot(location+11): fetch_tile(column+2) \
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slot(location+12): fetch_tile_name(column+3) \
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sprite_y_read(location+13, sprite+2); \
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slot(location+14): \
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slot(location+15): fetch_tile(column+3)
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LineBuffer &line_buffer = line_buffers_[fetch_pointer_.row];
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LineBuffer &sprite_selection_buffer = line_buffers_[(fetch_pointer_.row + 1) % mode_timing_.total_lines];
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const size_t row_base = pattern_name_address_ & (size_t((fetch_pointer_.row << 2)&~31) | 0x3c00);
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size_t pattern_base = pattern_generator_table_address_;
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size_t colour_base = colour_table_address_;
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int colour_name_shift = 6;
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if(screen_mode_ == ScreenMode::Graphics) {
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// If this is high resolution mode, allow the row number to affect the pattern and colour addresses.
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pattern_base &= size_t(0x2000 | ((fetch_pointer_.row & 0xc0) << 5));
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colour_base &= size_t(0x2000 | ((fetch_pointer_.row & 0xc0) << 5));
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colour_base += size_t(fetch_pointer_.row & 7);
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colour_name_shift = 0;
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} else {
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colour_base &= size_t(0xffc0);
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pattern_base &= size_t(0x3800);
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}
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if(screen_mode_ == ScreenMode::MultiColour) {
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pattern_base += size_t((fetch_pointer_.row >> 2) & 7);
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} else {
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pattern_base += size_t(fetch_pointer_.row & 7);
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}
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switch(start) {
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default: assert(false);
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external_slots_2(0);
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sprite_fetch_block(2, 0);
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sprite_fetch_block(8, 1);
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sprite_fetch_coordinates(14, 2);
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external_slots_4(16);
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external_slot(20);
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sprite_fetch_graphics(21, 2);
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sprite_fetch_block(25, 3);
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slot(31):
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sprite_selection_buffer.reset_sprite_collection();
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do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(31));
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external_slots_2(32);
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external_slot(34);
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sprite_y_read(35, 0);
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sprite_y_read(36, 1);
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sprite_y_read(37, 2);
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sprite_y_read(38, 3);
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sprite_y_read(39, 4);
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sprite_y_read(40, 5);
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sprite_y_read(41, 6);
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sprite_y_read(42, 7);
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background_fetch_block(43, 0, 8);
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background_fetch_block(59, 4, 11);
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background_fetch_block(75, 8, 14);
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background_fetch_block(91, 12, 17);
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background_fetch_block(107, 16, 20);
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background_fetch_block(123, 20, 23);
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background_fetch_block(139, 24, 26);
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background_fetch_block(155, 28, 29);
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return;
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}
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#undef background_fetch_block
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#undef fetch_tile
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#undef fetch_tile_name
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#undef sprite_y_read
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#undef sprite_fetch_block
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#undef sprite_fetch_graphics
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#undef sprite_fetch_coordinates
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}
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// MARK: - Master System
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template <Personality personality>
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template<bool use_end> void Base<personality>::fetch_sms(int start, int end) {
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if constexpr (is_sega_vdp(personality)) {
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#define sprite_fetch(sprite) {\
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line_buffer.active_sprites[sprite].x = \
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ram_[\
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Storage<personality>::sprite_attribute_table_address_ & size_t(0x3f80 | (line_buffer.active_sprites[sprite].index << 1))\
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] - (Storage<personality>::shift_sprites_8px_left_ ? 8 : 0); \
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const uint8_t name = ram_[\
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Storage<personality>::sprite_attribute_table_address_ & size_t(0x3f81 | (line_buffer.active_sprites[sprite].index << 1))\
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] & (sprites_16x16_ ? ~1 : ~0);\
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const size_t graphic_location = Storage<personality>::sprite_generator_table_address_ & size_t(0x2000 | (name << 5) | (line_buffer.active_sprites[sprite].row << 2)); \
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line_buffer.active_sprites[sprite].image[0] = ram_[graphic_location]; \
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line_buffer.active_sprites[sprite].image[1] = ram_[graphic_location+1]; \
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line_buffer.active_sprites[sprite].image[2] = ram_[graphic_location+2]; \
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line_buffer.active_sprites[sprite].image[3] = ram_[graphic_location+3]; \
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}
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#define sprite_fetch_block(location, sprite) \
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slot(location): \
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slot(location+1): \
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slot(location+2): \
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slot(location+3): \
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slot(location+4): \
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slot(location+5): \
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sprite_fetch(sprite);\
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sprite_fetch(sprite+1);
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#define sprite_y_read(location, sprite) \
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slot(location): \
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posit_sprite(sprite_selection_buffer, sprite, ram_[Storage<personality>::sprite_attribute_table_address_ & ((sprite) | 0x3f00)], fetch_pointer_.row); \
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posit_sprite(sprite_selection_buffer, sprite+1, ram_[Storage<personality>::sprite_attribute_table_address_ & ((sprite + 1) | 0x3f00)], fetch_pointer_.row); \
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#define fetch_tile_name(column, row_info) {\
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const size_t scrolled_column = (column - horizontal_offset) & 0x1f;\
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const size_t address = row_info.pattern_address_base + (scrolled_column << 1); \
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line_buffer.names[column].flags = ram_[address+1]; \
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line_buffer.names[column].offset = size_t( \
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(((line_buffer.names[column].flags&1) << 8) | ram_[address]) << 5 \
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) + row_info.sub_row[(line_buffer.names[column].flags&4) >> 2]; \
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}
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#define fetch_tile(column) \
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line_buffer.patterns[column][0] = ram_[line_buffer.names[column].offset]; \
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line_buffer.patterns[column][1] = ram_[line_buffer.names[column].offset+1]; \
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line_buffer.patterns[column][2] = ram_[line_buffer.names[column].offset+2]; \
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line_buffer.patterns[column][3] = ram_[line_buffer.names[column].offset+3];
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#define background_fetch_block(location, column, sprite, row_info) \
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slot(location): fetch_tile_name(column, row_info) \
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external_slot(location+1); \
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slot(location+2): \
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slot(location+3): \
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slot(location+4): \
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fetch_tile(column) \
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fetch_tile_name(column+1, row_info) \
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sprite_y_read(location+5, sprite); \
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slot(location+6): \
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slot(location+7): \
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slot(location+8): \
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fetch_tile(column+1) \
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fetch_tile_name(column+2, row_info) \
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sprite_y_read(location+9, sprite+2); \
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slot(location+10): \
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slot(location+11): \
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slot(location+12): \
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fetch_tile(column+2) \
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fetch_tile_name(column+3, row_info) \
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sprite_y_read(location+13, sprite+4); \
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slot(location+14): \
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slot(location+15): fetch_tile(column+3)
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// Determine the coarse horizontal scrolling offset; this isn't applied on the first two lines if the programmer has requested it.
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LineBuffer &line_buffer = line_buffers_[fetch_pointer_.row];
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LineBuffer &sprite_selection_buffer = line_buffers_[(fetch_pointer_.row + 1) % mode_timing_.total_lines];
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const int horizontal_offset = (fetch_pointer_.row >= 16 || !Storage<personality>::horizontal_scroll_lock_) ? (line_buffer.latched_horizontal_scroll >> 3) : 0;
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// Limit address bits in use if this is a SMS2 mode.
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const bool is_tall_mode = mode_timing_.pixel_lines != 192;
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const size_t pattern_name_address = Storage<personality>::pattern_name_address_ | (is_tall_mode ? 0x800 : 0);
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const size_t pattern_name_offset = is_tall_mode ? 0x100 : 0;
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// Determine row info for the screen both (i) if vertical scrolling is applied; and (ii) if it isn't.
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// The programmer can opt out of applying vertical scrolling to the right-hand portion of the display.
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const int scrolled_row = (fetch_pointer_.row + Storage<personality>::latched_vertical_scroll_) % (is_tall_mode ? 256 : 224);
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struct RowInfo {
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size_t pattern_address_base;
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size_t sub_row[2];
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};
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const RowInfo scrolled_row_info = {
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(pattern_name_address & size_t(((scrolled_row & ~7) << 3) | 0x3800)) - pattern_name_offset,
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{size_t((scrolled_row & 7) << 2), 28 ^ size_t((scrolled_row & 7) << 2)}
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};
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RowInfo row_info;
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if(Storage<personality>::vertical_scroll_lock_) {
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row_info.pattern_address_base = (pattern_name_address & size_t(((fetch_pointer_.row & ~7) << 3) | 0x3800)) - pattern_name_offset;
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row_info.sub_row[0] = size_t((fetch_pointer_.row & 7) << 2);
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row_info.sub_row[1] = 28 ^ size_t((fetch_pointer_.row & 7) << 2);
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} else row_info = scrolled_row_info;
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// ... and do the actual fetching, which follows this routine:
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switch(start) {
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default: assert(false);
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sprite_fetch_block(0, 0);
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sprite_fetch_block(6, 2);
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external_slots_4(12);
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external_slot(16);
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sprite_fetch_block(17, 4);
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sprite_fetch_block(23, 6);
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slot(29):
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sprite_selection_buffer.reset_sprite_collection();
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do_external_slot(to_internal<personality, Clock::TMSMemoryWindow>(29));
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external_slot(30);
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sprite_y_read(31, 0);
|
|
sprite_y_read(32, 2);
|
|
sprite_y_read(33, 4);
|
|
sprite_y_read(34, 6);
|
|
sprite_y_read(35, 8);
|
|
sprite_y_read(36, 10);
|
|
sprite_y_read(37, 12);
|
|
sprite_y_read(38, 14);
|
|
|
|
background_fetch_block(39, 0, 16, scrolled_row_info);
|
|
background_fetch_block(55, 4, 22, scrolled_row_info);
|
|
background_fetch_block(71, 8, 28, scrolled_row_info);
|
|
background_fetch_block(87, 12, 34, scrolled_row_info);
|
|
background_fetch_block(103, 16, 40, scrolled_row_info);
|
|
background_fetch_block(119, 20, 46, scrolled_row_info);
|
|
background_fetch_block(135, 24, 52, row_info);
|
|
background_fetch_block(151, 28, 58, row_info);
|
|
|
|
external_slots_4(167);
|
|
|
|
return;
|
|
}
|
|
|
|
#undef background_fetch_block
|
|
#undef fetch_tile
|
|
#undef fetch_tile_name
|
|
#undef sprite_y_read
|
|
#undef sprite_fetch_block
|
|
#undef sprite_fetch
|
|
}
|
|
}
|
|
|
|
// MARK: - Yamaha
|
|
|
|
// TODO.
|
|
|
|
template <Personality personality>
|
|
template<bool use_end> void Base<personality>::fetch_yamaha_refresh(int start, int end) {
|
|
(void)start;
|
|
(void)end;
|
|
}
|
|
|
|
template <Personality personality>
|
|
template<bool use_end, bool fetch_sprites> void Base<personality>::fetch_yamaha(int start, int end) {
|
|
/*
|
|
Per http://map.grauw.nl/articles/vdp-vram-timing/vdp-timing.html :
|
|
|
|
The major change compared to the previous mode is that now the VDP needs to fetch extra data
|
|
for the bitmap rendering. These fetches happen in 32 blocks of 4 bytes (screen 5/6) or
|
|
8 bytes (screen 7/8). The fetches within one block happen in burst mode. This means that
|
|
one block takes 18 cycles (screen 5/6) or 20 cycles (screen 7/8). Though later we'll see
|
|
that the two spare cycles for screen 5/6 are not used for anything else, so for simplicity
|
|
we can say that in all bitmap modes a bitmap-fetch-block takes 20 cycles. This is even
|
|
clearer if you look at the RAS signal: this signal follows the exact same pattern in all
|
|
(bitmap) screen modes, so in screen 5/6 it remains active for two cycles longer than
|
|
strictly necessary.
|
|
|
|
Actually before these 32 blocks there's one extra dummy block. This block has the same timing
|
|
as the other blocks, but it always reads address 0x1FFFF. From an emulator point of view,
|
|
these dummy reads don't matter, it only matters that at those moments no other VRAM accesses
|
|
can occur.
|
|
*/
|
|
|
|
(void)start;
|
|
(void)end;
|
|
}
|
|
|
|
// MARK: - Mega Drive
|
|
|
|
// TODO.
|
|
|
|
#undef external_slot
|
|
#undef slot
|
|
|
|
#endif /* Fetch_hpp */
|