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Merge pull request #144 from TomHarte/HiRes

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Corrects various ZX80/81 video deficiencies
This commit is contained in:
Thomas Harte 2017-07-09 17:17:16 -04:00 committed by GitHub
commit a0367d6669
3 changed files with 15 additions and 10 deletions
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1
Machines/ZX8081/Video.cpp
View File

@ -76,6 +76,7 @@ void Video::set_sync(bool sync) {
void Video::output_byte(uint8_t byte) {
// Complete whatever was going on.
if(sync_) return;
flush();
// Grab a buffer if one isn't already available.

22
Machines/ZX8081/ZX8081.cpp
View File

@ -25,7 +25,8 @@ Machine::Machine() :
use_fast_tape_hack_(false),
tape_advance_delay_(0),
tape_is_automatically_playing_(false),
tape_is_playing_(false) {
tape_is_playing_(false),
has_latched_video_byte_(false) {
set_clock_rate(ZX8081ClockRate);
tape_player_.set_motor_control(true);
clear_all_keys();
@ -76,11 +77,11 @@ int Machine::perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
case CPU::Z80::PartialMachineCycle::Output:
if(!(address & 2)) nmi_is_enabled_ = false;
if(!(address & 1)) nmi_is_enabled_ = is_zx81_;
if((address&3) == 3) {
if(!nmi_is_enabled_) {
set_vsync(false);
line_counter_ = 0;
}
if(!nmi_is_enabled_) {
// Line counter reset is held low while vsync is active; simulate that lazily by performing
// an instant reset upon the transition from active to inactive.
if(vsync_) line_counter_ = 0;
set_vsync(false);
}
break;
@ -114,8 +115,8 @@ int Machine::perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
set_interrupt_line(true, -2);
set_interrupt_line(false);
}
if(latched_video_byte_) {
size_t char_address = (size_t)((address & 0xff00) | ((latched_video_byte_ & 0x3f) << 3) | line_counter_);
if(has_latched_video_byte_) {
size_t char_address = (size_t)((address & 0xfe00) | ((latched_video_byte_ & 0x3f) << 3) | line_counter_);
uint8_t mask = (latched_video_byte_ & 0x80) ? 0x00 : 0xff;
if(char_address < ram_base_) {
latched_video_byte_ = rom_[char_address & rom_mask_] ^ mask;
@ -124,7 +125,7 @@ int Machine::perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
}
video_->output_byte(latched_video_byte_);
latched_video_byte_ = 0;
has_latched_video_byte_ = false;
}
break;
@ -161,10 +162,11 @@ int Machine::perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
uint8_t value = ram_[address & ram_mask_];
// If this is an M1 cycle reading from above the 32kb mark and HALT is not
// currently active, perform a video output and return a NOP. Otherwise,
// currently active, latch for video output and return a NOP. Otherwise,
// just return the value as read.
if(is_opcode_read && address&0x8000 && !(value & 0x40) && !get_halt_line()) {
latched_video_byte_ = value;
has_latched_video_byte_ = true;
*cycle.value = 0;
} else *cycle.value = value;
}

2
Machines/ZX8081/ZX8081.hpp
View File

@ -98,7 +98,9 @@ class Machine:
bool is_zx81_;
bool nmi_is_enabled_;
int vsync_start_cycle_, vsync_end_cycle_;
uint8_t latched_video_byte_;
bool has_latched_video_byte_;
bool use_fast_tape_hack_;
bool use_automatic_tape_motor_control_;