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Reduces CheckingWriteProtect costs, negligibly.

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This commit is contained in:
Thomas Harte 2019-07-15 22:39:55 -04:00
parent ca37fd8f4c
commit 67055d8b56
1 changed files with 6 additions and 4 deletions
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10
Components/DiskII/IWM.cpp
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@ -86,7 +86,7 @@ uint8_t IWM::read(int address) {
return uint8_t(
(mode_&0x1f) |
((state_ & ENABLE) ? 0x20 : 0x00) |
sense()
(sense() & 0x80)
);
} break;
@ -292,8 +292,10 @@ void IWM::run_for(const Cycles cycles) {
break;
case ShiftMode::CheckingWriteProtect:
while(--integer_cycles) {
shift_register_ = (shift_register_ >> 1) | sense();
if(integer_cycles < 8) {
shift_register_ = (shift_register_ >> integer_cycles) | (sense() & (0xff << (8 - integer_cycles)));
} else {
shift_register_ = sense();
}
/* Deliberate fallthrough. */
@ -330,7 +332,7 @@ void IWM::select_shift_mode() {
}
uint8_t IWM::sense() {
return drives_[active_drive_] ? (drives_[active_drive_]->read() ? 0x80 : 0x00) : 0x80;
return drives_[active_drive_] ? (drives_[active_drive_]->read() ? 0xff : 0x00) : 0xff;
}
void IWM::process_event(const Storage::Disk::Drive::Event &event) {