paulbergmann_mpstubs/machine/cmos.cc

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#include "machine/cmos.h"
#include "machine/core.h"
#include "machine/ioport.h"
namespace CMOS {
static IOPort address(0x70);
static IOPort data(0x71);
namespace NMI {
static const uint8_t mask = 0x80;
// Cache NMI to speed things up
static bool disabled = false;
void enable() {
bool status = Core::Interrupt::disable();
uint8_t value = address.inb();
value &= ~mask;
address.outb(value);
Core::Interrupt::restore(status);
disabled = false;
}
void disable() {
bool status = Core::Interrupt::disable();
uint8_t value = address.inb();
value |= mask;
address.outb(value);
Core::Interrupt::restore(status);
disabled = true;
}
bool isEnabled() {
disabled = (address.inb() & mask) != 0;
return !disabled;
}
} // namespace NMI
static void setAddress(enum Register reg) {
uint8_t value = reg;
// The highest bit controls the Non Maskable Interrupt
// so we don't want to accidentally change it.
if (NMI::disabled) {
value |= NMI::mask;
} else {
value &= ~NMI::mask;
}
address.outb(value);
}
uint8_t read(enum Register reg) {
setAddress(reg);
return data.inb();
}
void write(enum Register reg, uint8_t value) {
setAddress(reg);
data.outb(value);
}
} // namespace CMOS