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Resolves remaining sources of text mode instability.

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This commit is contained in:
Thomas Harte 2017-11-30 22:48:07 -05:00
parent edcbb3dfed
commit 3c8d2d579d
2 changed files with 19 additions and 16 deletions
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29
Components/9918/9918.cpp
View File

@ -84,29 +84,31 @@ void TMS9918::run_for(const HalfCycles cycles) {
while(int_cycles) { while(int_cycles) {
int cycles_left = std::min(342 - column_, int_cycles); int cycles_left = std::min(342 - column_, int_cycles);
column_ += cycles_left; column_ += cycles_left;
int_cycles -= cycles_left;
if(row_ < 192 && !blank_screen_) { if(row_ < 192 && !blank_screen_) {
// ------------------------ // ------------------------
// Perform memory accesses. // Perform memory accesses.
// ------------------------ // ------------------------
const int access_slot = column_ >> 1; // There are only 171 available memory accesses per line.
switch(line_mode_) { switch(line_mode_) {
case LineMode::Text: case LineMode::Text:
while(access_pointer_ < (column_ >> 1)) { while(access_pointer_ < access_slot) {
if(access_pointer_ < 29) { if(access_pointer_ < 29) {
access_pointer_ = std::min(29, column_ >> 1); access_pointer_ = std::min(29, access_slot);
} }
if(access_pointer_ >= 29) { if(access_pointer_ >= 29) {
const int row_base = pattern_name_address_ + (row_ >> 3) * 40; int row_base = pattern_name_address_ + (row_ >> 3) * 40;
int character_column = (access_pointer_ - 29) / 3; int character_column = (access_pointer_ - 29) / 3;
const int end = std::min(149, column_); const int end = std::min(149, access_slot);
while(access_pointer_ < end) { while(access_pointer_ < end) {
switch(access_pointer_%3) { switch(access_pointer_%3) {
case 2: case 2:
pattern_name_ = ram_[row_base + character_column]; pattern_name_ = ram_[row_base + character_column];
break; break;
case 1: break; // TODO: sprites / CPU access. case 1: break; // TODO: CPU access.
case 0: case 0:
pattern_buffer_[character_column] = ram_[pattern_generator_table_address_ + (pattern_name_ << 3) + (row_ & 7)]; pattern_buffer_[character_column] = ram_[pattern_generator_table_address_ + (pattern_name_ << 3) + (row_ & 7)];
character_column++; character_column++;
@ -116,18 +118,18 @@ void TMS9918::run_for(const HalfCycles cycles) {
} }
} }
if(access_pointer_ >= 149) { if(access_pointer_ >= 149) {
access_pointer_ = column_ >> 1; access_pointer_ = access_slot;
} }
} }
break; break;
case LineMode::Character: case LineMode::Character:
while(access_pointer_ < (column_ >> 1)) { while(access_pointer_ < access_slot) {
if(access_pointer_ < 26) { if(access_pointer_ < 26) {
access_pointer_ = std::min(26, column_ >> 1); access_pointer_ = std::min(26, access_slot);
} }
if(access_pointer_ >= 26) { if(access_pointer_ >= 26) {
int end = std::min(154, column_); int end = std::min(154, access_slot);
// TODO: optimise this mess. // TODO: optimise this mess.
const int row_base = pattern_name_address_ + ((row_ << 2)&~31); const int row_base = pattern_name_address_ + ((row_ << 2)&~31);
@ -149,7 +151,7 @@ void TMS9918::run_for(const HalfCycles cycles) {
} }
} }
if(access_pointer_ >= 154) { if(access_pointer_ >= 154) {
access_pointer_ = column_ >> 1; access_pointer_ = access_slot;
} }
} }
break; break;
@ -222,10 +224,11 @@ void TMS9918::run_for(const HalfCycles cycles) {
} }
break; break;
} }
}
if(output_column_ == first_right_border_column_) { if(output_column_ == first_right_border_column_) {
crt_->output_data(static_cast<unsigned int>(first_right_border_column_ - first_pixel_column_), 1); crt_->output_data(static_cast<unsigned int>(first_right_border_column_ - first_pixel_column_), 1);
pixel_target_ = nullptr;
}
} }
} }
@ -253,13 +256,13 @@ void TMS9918::run_for(const HalfCycles cycles) {
} }
} }
int_cycles -= cycles_left;
if(column_ == 342) { if(column_ == 342) {
access_pointer_ = column_ = output_column_ = 0; access_pointer_ = column_ = output_column_ = 0;
row_ = (row_ + 1) % frame_lines_; row_ = (row_ + 1) % frame_lines_;
if(row_ == 192) status_ |= 0x80; if(row_ == 192) status_ |= 0x80;
screen_mode_ = next_screen_mode_; screen_mode_ = next_screen_mode_;
blank_screen_ = next_blank_screen_;
switch(screen_mode_) { switch(screen_mode_) {
case 2: case 2:
line_mode_ = LineMode::Text; line_mode_ = LineMode::Text;
@ -313,7 +316,7 @@ void TMS9918::set_register(int address, uint8_t value) {
break; break;
case 1: case 1:
blank_screen_ = !(low_write_ & 0x40); next_blank_screen_ = !(low_write_ & 0x40);
generate_interrupts_ = !!(low_write_ & 0x20); generate_interrupts_ = !!(low_write_ & 0x20);
next_screen_mode_ = (screen_mode_ & 1) | ((low_write_ & 0x18) >> 3); next_screen_mode_ = (screen_mode_ & 1) | ((low_write_ & 0x18) >> 3);
sprites_16x16_ = !!(low_write_ & 0x02); sprites_16x16_ = !!(low_write_ & 0x02);

2
Components/9918/9918.hpp
View File

@ -62,7 +62,7 @@ class TMS9918 {
// The various register flags. // The various register flags.
int next_screen_mode_ = 0, screen_mode_ = 0; int next_screen_mode_ = 0, screen_mode_ = 0;
bool blank_screen_ = true; bool next_blank_screen_ = true, blank_screen_ = true;
bool sprites_16x16_ = false; bool sprites_16x16_ = false;
bool sprites_magnified_ = false; bool sprites_magnified_ = false;
bool generate_interrupts_ = false; bool generate_interrupts_ = false;