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Implements multicolour mode on the TMS.

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This commit is contained in:
Thomas Harte 2018-03-02 23:08:01 -05:00
parent fdfd72a42c
commit ea13c7dd32
1 changed files with 55 additions and 32 deletions
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37
Components/9918/9918.cpp
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@ -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<size_t>(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];
@ -435,10 +448,19 @@ void TMS9918::run_for(const HalfCycles cycles) {
}
// Paint the background tiles.
const int pixels_left = pixels_end - output_column_;
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_ += pixels_left;
} else {
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;
@ -466,6 +488,7 @@ void TMS9918::run_for(const HalfCycles cycles) {
colours[0] = palette[(colour & 15) ? (colour & 15) : background_colour_];
colours[1] = palette[(colour >> 4) ? (colour >> 4) : background_colour_];
}
}
// Paint sprites and check for collisions.
if(sprite_set.active_sprite_slot) {
@ -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);