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Implement much of Yamaha line interrupts.

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This commit is contained in:
Thomas Harte 2023-01-30 21:24:53 -05:00
parent 30a2b1611f
commit 492a170b20
1 changed files with 25 additions and 5 deletions

30
Components/9918/Implementation/9918.cpp

@ -37,6 +37,11 @@ Base<personality>::Base() :
mode_timing_.end_of_frame_interrupt_position.row = 193;
}
if constexpr (is_yamaha_vdp(personality)) {
// TODO: start of sync, or end of sync?
mode_timing_.line_interrupt_position = Timing<personality>::StartOfSync;
}
// Establish that output is delayed after reading by `output_lag` cycles; start
// at a random position.
fetch_pointer_.row = rand() % 262;
@ -255,6 +260,12 @@ void TMS9918<personality>::run_for(const HalfCycles cycles) {
}
}
if constexpr (is_yamaha_vdp(personality)) {
if(this->fetch_pointer_.row == this->line_interrupt_target_) {
this->line_interrupt_pending_ = true;
}
}
// TODO: the V9938 provides line interrupts from direct specification of the target line.
// So life is easy.
}
@ -723,6 +734,7 @@ void Base<personality>::commit_register(int reg, uint8_t value) {
(Storage<personality>::mode_ & 3) |
((value & 0xe) << 1)
);
enable_line_interrupts_ = value & 0x10;
LOG("TODO: Yamaha additional mode selection; " << PADHEX(2) << +value);
// b1–b3: M3–M5
@ -819,7 +831,7 @@ void Base<personality>::commit_register(int reg, uint8_t value) {
break;
case 19:
LOG("TODO: Yamaha interrupt line; " << PADHEX(2) << +value);
line_interrupt_target_ = value;
// b0–b7: line to match for interrupts (if eabled)
break;
@ -1020,16 +1032,20 @@ uint8_t Base<personality>::read_register() {
default:
case 0: break;
case 1:
case 1: {
// b7 = light pen; set when light is detected, reset on read;
// or: mouse button 2 currently down.
// b6 = light pen button or mouse button 1.
// b5–b1 = VDP identification (1 = 9938; 2 = 9958)
// b0 = set when the VDP reaches the line provided in the line interrupt register.
// Reset upon read.
return
personality == Personality::V9938 ? 0x2 : 0x4;
break;
const uint8_t result =
(personality == Personality::V9938 ? 0x2 : 0x4) |
(line_interrupt_pending_ ? 0x01 : 0x00);
line_interrupt_pending_ = false;
return result;
} break;
case 2: {
// b7 = transfer ready flag (i.e. VDP ready for next transfer)
@ -1189,6 +1205,10 @@ HalfCycles TMS9918<personality>::get_next_sequence_point() const {
}
}
if constexpr (is_yamaha_vdp(personality)) {
// TODO: time to next retrace interrupt.
}
// If there's actually no interrupt upcoming, despite being enabled, either return
// the frame end interrupt or no interrupt pending as appropriate.
if(next_line_interrupt_row == -1) {