diff --git a/Components/9918/9918.cpp b/Components/9918/9918.cpp index 58d4d7fbf..c09deaa9f 100644 --- a/Components/9918/9918.cpp +++ b/Components/9918/9918.cpp @@ -72,6 +72,15 @@ struct ReverseTable { } } reverse_table; +// Bits are reversed in the internal mode value; they're stored +// in the order M1 M2 M3. Hence the definitions below. +enum ScreenMode { + Text = 4, + MultiColour = 2, + ColouredText = 0, + Graphics = 1 +}; + } TMS9918Base::TMS9918Base() : @@ -293,7 +302,8 @@ void TMS9918::run_for(const HalfCycles cycles) { int row_base = pattern_name_address_; int pattern_base = pattern_generator_table_address_; int colour_base = colour_table_address_; - if(screen_mode_ == 1) { + if(screen_mode_ == ScreenMode::Graphics) { + // If this is high resolution mode, allow the row number to affect the pattern and colour addresses. pattern_base &= 0x2000 | ((row_ & 0xc0) << 5); colour_base &= 0x2000 | ((row_ & 0xc0) << 5); } @@ -304,7 +314,7 @@ void TMS9918::run_for(const HalfCycles cycles) { const int pattern_names_end = (end - 27 + 3) >> 2; std::memcpy(&pattern_names_[pattern_names_start], &ram_[row_base + pattern_names_start], static_cast(pattern_names_end - pattern_names_start)); - // Colours are collected ever fourth window starting from window 29. + // Colours are collected every fourth window starting from window 29. const int colours_start = (access_pointer_ - 29 + 3) >> 2; const int colours_end = (end - 29 + 3) >> 2; if(screen_mode_ != 1) { @@ -320,8 +330,11 @@ void TMS9918::run_for(const HalfCycles cycles) { // Patterns are collected ever fourth window starting from window 30. const int pattern_buffer_start = (access_pointer_ - 30 + 3) >> 2; const int pattern_buffer_end = (end - 30 + 3) >> 2; + + // Multicolour mode uss a different function of row to pick bytes + const int row = (screen_mode_ != 2) ? (row_ & 7) : ((row_ >> 2) & 7); for(int column = pattern_buffer_start; column < pattern_buffer_end; ++column) { - pattern_buffer_[column] = ram_[pattern_base + (pattern_names_[column] << 3) + (row_ & 7)]; + pattern_buffer_[column] = ram_[pattern_base + (pattern_names_[column] << 3) + row]; } // Sprite slots occur in three quarters of ever fourth window starting from window 28. @@ -421,7 +434,7 @@ void TMS9918::run_for(const HalfCycles cycles) { case LineMode::Character: { // If this is the start of the visible area, seed sprite shifter positions. SpriteSet &sprite_set = sprite_sets_[active_sprite_set_ ^ 1]; - if(line_mode_ == LineMode::Character && output_column_ == first_pixel_column_) { + if(output_column_ == first_pixel_column_) { int c = sprite_set.active_sprite_slot; while(c--) { SpriteSet::ActiveSprite &sprite = sprite_set.active_sprites[c]; @@ -435,36 +448,46 @@ void TMS9918::run_for(const HalfCycles cycles) { } // Paint the background tiles. - const int shift = (output_column_ - first_pixel_column_) & 7; - int byte_column = (output_column_ - first_pixel_column_) >> 3; - const int pixels_left = pixels_end - output_column_; - int length = std::min(pixels_left, 8 - shift); - - int pattern = reverse_table.map[pattern_buffer_[byte_column]] >> shift; - uint8_t colour = colour_buffer_[byte_column]; - uint32_t colours[2] = { - palette[(colour & 15) ? (colour & 15) : background_colour_], - palette[(colour >> 4) ? (colour >> 4) : background_colour_] - }; - - int background_pixels_left = pixels_left; - while(true) { - background_pixels_left -= length; - for(int c = 0; c < length; ++c) { - pixel_target_[c] = colours[pattern&0x01]; - pattern >>= 1; + if(screen_mode_ == ScreenMode::MultiColour) { + int pixel_location = output_column_ - first_pixel_column_; + for(int c = 0; c < pixels_left; ++c) { + pixel_target_[c] = palette[ + (pattern_buffer_[(pixel_location + c) >> 3] >> (((pixel_location + c) & 4)^4)) & 15 + ]; } - pixel_target_ += length; + pixel_target_ += pixels_left; + } else { + const int shift = (output_column_ - first_pixel_column_) & 7; + int byte_column = (output_column_ - first_pixel_column_) >> 3; - if(!background_pixels_left) break; - length = std::min(8, background_pixels_left); - byte_column++; + int length = std::min(pixels_left, 8 - shift); - pattern = reverse_table.map[pattern_buffer_[byte_column]]; - colour = colour_buffer_[byte_column]; - colours[0] = palette[(colour & 15) ? (colour & 15) : background_colour_]; - colours[1] = palette[(colour >> 4) ? (colour >> 4) : background_colour_]; + int pattern = reverse_table.map[pattern_buffer_[byte_column]] >> shift; + uint8_t colour = colour_buffer_[byte_column]; + uint32_t colours[2] = { + palette[(colour & 15) ? (colour & 15) : background_colour_], + palette[(colour >> 4) ? (colour >> 4) : background_colour_] + }; + + int background_pixels_left = pixels_left; + while(true) { + background_pixels_left -= length; + for(int c = 0; c < length; ++c) { + pixel_target_[c] = colours[pattern&0x01]; + pattern >>= 1; + } + pixel_target_ += length; + + if(!background_pixels_left) break; + length = std::min(8, background_pixels_left); + byte_column++; + + pattern = reverse_table.map[pattern_buffer_[byte_column]]; + colour = colour_buffer_[byte_column]; + colours[0] = palette[(colour & 15) ? (colour & 15) : background_colour_]; + colours[1] = palette[(colour >> 4) ? (colour >> 4) : background_colour_]; + } } // Paint sprites and check for collisions. @@ -554,7 +577,7 @@ void TMS9918::run_for(const HalfCycles cycles) { screen_mode_ = next_screen_mode_; blank_screen_ = next_blank_screen_; switch(screen_mode_) { - case 2: + case ScreenMode::Text: line_mode_ = LineMode::Text; first_pixel_column_ = 69; first_right_border_column_ = 309; @@ -608,7 +631,7 @@ void TMS9918::set_register(int address, uint8_t value) { case 1: next_blank_screen_ = !(low_write_ & 0x40); generate_interrupts_ = !!(low_write_ & 0x20); - next_screen_mode_ = (next_screen_mode_ & 1) | ((low_write_ & 0x18) >> 3); + next_screen_mode_ = (next_screen_mode_ & 1) | ((low_write_ & 0x18) >> 2); sprites_16x16_ = !!(low_write_ & 0x02); sprites_magnified_ = !!(low_write_ & 0x01);