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collapseos/emul/hw/sms/port.c

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#include "port.h"
void ports_init(Ports *ports)
{
ports->ctl = 0xff;
ports->TRA = TRI_HIGHZ;
ports->THA = TRI_HIGHZ;
ports->TRB = TRI_HIGHZ;
ports->THB = TRI_HIGHZ;
}
uint8_t ports_ctl_rd(Ports *ports)
{
return ports->ctl;
}
void ports_ctl_wr(Ports *ports, uint8_t val)
{
ports->ctl = val;
ports->TRA = TRI_HIGHZ;
ports->THA = TRI_HIGHZ;
ports->TRB = TRI_HIGHZ;
ports->THB = TRI_HIGHZ;
if ((val & 0x01) == 0) {
ports->TRA = ((val & 0x10) == 0) ? TRI_LOW : TRI_HIGH;
}
if ((val & 0x02) == 0) {
ports->THA = ((val & 0x20) == 0) ? TRI_LOW : TRI_HIGH;
}
if ((val & 0x04) == 0) {
ports->TRB = ((val & 0x40) == 0) ? TRI_LOW : TRI_HIGH;
}
if ((val & 0x08) == 0) {
ports->THB = ((val & 0x80) == 0) ? TRI_LOW : TRI_HIGH;
}
}
uint8_t ports_A_rd(Ports *ports)
{
// Bits 7:6 are port B's Down/Up
// Bits 5:0 are port A's TR/TL/R/L/D/U
uint8_t res = 0xff;
if (ports->portA_rd != NULL) {
res &= ports->portA_rd() | 0b11000000;
}
if (ports->portB_rd != NULL) {
res &= (ports->portB_rd() << 6) | 0b00111111;
}
return res;
}
uint8_t ports_B_rd(Ports *ports)
{
// Bit 7: Port B's TH
// Bit 6: Port A's TH
// Bit 5: unused
// Bit 4: unused (reset button)
// Bits 3:0 are port B's TR/TL/R/L
uint8_t res = 0xff;
if (ports->portA_rd != NULL) {
res &= ports->portA_rd() | 0b10111111;
}
if (ports->portB_rd != NULL) {
uint8_t portb = ports->portB_rd();
res &= (portb << 1) | 0b01111111; // TH
res &= (portb >> 2) | 0b11110000; // TR/TL/R/L
}
return res;
}