int serial_iec_read(unsigned int unit, unsigned int secondary, BYTE *data)
{
if (listen) {
serial_iec_bus_unlisten(unit, (BYTE)secondary, serial_iec_set_st);
listen = 0;
}
if (!talk) {
serial_iec_bus_talk(unit | 0x40, (BYTE)secondary, serial_iec_set_st);
talk = 1;
}
*data = serial_iec_bus_read(unit, (BYTE)secondary, serial_iec_set_st);
return serial_iec_st;
}
/* Command Serial Bus to TALK, LISTEN, UNTALK, or UNLISTEN, and send the
Secondary Address to Serial Bus under Attention. */
int serial_trap_attention(void)
{
BYTE b;
serial_t *p;
/*
* Which Secondary Address ?
*/
b = mem_read(((BYTE)(BSOUR))); /* BSOUR - character for serial bus */
if (((b & 0xf0) == 0x20) || ((b & 0xf0) == 0x40)) {
if (serial_truedrive && ((b & 0x0f) != 4 ) && ((b & 0x0f) != 5)) {
/* Set TrapDevice even if the trap is not taken; needed
for other traps. */
TrapDevice = b;
return 0;
}
} else {
if (serial_truedrive && ((TrapDevice & 0x0f) != 4)
&& ((TrapDevice & 0x0f) != 5)) {
return 0;
}
}
/* do a flush if unlisten for close and command channel */
if (b == 0x3f) {
serial_iec_bus_unlisten(TrapDevice, TrapSecondary, serial_set_st);
} else if (b == 0x5f) {
serial_iec_bus_untalk(TrapDevice, TrapSecondary, serial_set_st);
} else {
switch (b & 0xf0) {
case 0x20:
case 0x40:
TrapDevice = b;
break;
case 0x60:
TrapSecondary = b;
switch (TrapDevice & 0xf0) {
case 0x20:
serial_iec_bus_listen(TrapDevice, TrapSecondary, serial_set_st);
break;
case 0x40:
serial_iec_bus_talk(TrapDevice, TrapSecondary, serial_set_st);
break;
}
break;
case 0xe0:
TrapSecondary = b;
serial_iec_bus_close(TrapDevice, TrapSecondary, serial_set_st);
break;
case 0xf0:
TrapSecondary = b;
serial_iec_bus_open(TrapDevice, TrapSecondary, serial_set_st);
break;
}
}
p = serial_device_get(TrapDevice & 0x0f);
if (!(p->inuse)) {
serial_set_st(0x80);
}
MOS6510_REGS_SET_CARRY(&maincpu_regs, 0);
MOS6510_REGS_SET_INTERRUPT(&maincpu_regs, 0);
if (attention_callback_func) {
attention_callback_func();
}
return 1;
}