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Restored proper video output.

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This commit is contained in:
Thomas Harte 2017-06-21 21:18:09 -04:00
parent 7eeac3b586
commit e1355d4b62
2 changed files with 16 additions and 15 deletions
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30
Machines/ZX8081/ZX8081.cpp
View File

@ -61,7 +61,6 @@ int Machine::perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
return wait_cycles;
}
uint16_t refresh = 0;
uint16_t address = cycle.address ? *cycle.address : 0;
bool is_opcode_read = false;
switch(cycle.operation) {
@ -96,21 +95,28 @@ int Machine::perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
break;
case CPU::Z80::PartialMachineCycle::Refresh:
// The ZX80 and 81 signal an interrupt while refresh is active and bit 6 of the refresh
// address is low. The Z80 signals a refresh, providing the refresh address during the
// final two cycles of an opcode fetch. Therefore communicate a transient signalling
// of the IRQ line if necessary.
if(!(address & 0x40)) {
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(char_address < ram_base_) {
uint8_t mask = (latched_video_byte_ & 0x80) ? 0x00 : 0xff;
latched_video_byte_ = rom_[char_address & rom_mask_] ^ mask;
}
video_->output_byte(latched_video_byte_);
latched_video_byte_ = 0;
}
break;
case CPU::Z80::PartialMachineCycle::ReadOpcodeStart:
case CPU::Z80::PartialMachineCycle::ReadOpcodeWait:
// printf("%04x ", address);
// The ZX80 and 81 signal an interrupt while refresh is active and bit 6 of the refresh
// address is low. The Z80 signals a refresh, providing the refresh address during the
// final two cycles of an opcode fetch. Therefore communicate a transient signalling
// of the IRQ line if necessary.
// refresh = get_value_of_register(CPU::Z80::Register::Refresh);
// Check for use of the fast tape hack.
if(address == tape_trap_address_) { // TODO: && fast_tape_hack_enabled_
int next_byte = parser_.get_next_byte(tape_player_.get_tape());
@ -134,13 +140,7 @@ int Machine::perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
// currently active, perform a video output and return a NOP. Otherwise,
// just return the value as read.
if(is_opcode_read && address&0x8000 && !(value & 0x40) && !get_halt_line()) {
size_t char_address = (size_t)((refresh & 0xff00) | ((value & 0x3f) << 3) | line_counter_);
if(char_address < ram_base_) {
uint8_t mask = (value & 0x80) ? 0x00 : 0xff;
value = rom_[char_address & rom_mask_] ^ mask;
}
video_->output_byte(value);
latched_video_byte_ = value;
*cycle.value = 0;
} else *cycle.value = value;
}

1
Machines/ZX8081/ZX8081.hpp
View File

@ -89,6 +89,7 @@ class Machine:
bool is_zx81_;
bool nmi_is_enabled_;
int vsync_start_cycle_, vsync_end_cycle_;
uint8_t latched_video_byte_;
};
}