int main(void)
{
// init GPIO
PORTB = 0b11111000; // bits 0-2 are driven externally
DDRB = 0b00011000; // data read and data write latches
PORTC = 0b11111111; // pullups enabled
PORTD = 0b11111111; // pullups enabled
// init UART
UCSR0B = (1<<TXEN0);//|(1<<RXEN0);
UBRR0 = BAUD_MIDI;
// init timer
TCCR1B |= (1<<WGM12)|(1<<CS10); // timer1 ctc mode, no prescaler
TIMSK1 |= (1<<OCIE1A); // enable ctc interrupt
OCR1A = F_CPU / RTCFREQ - 1; // ctc value
// init emulator
MPU401_Init();
// enable interrupts
sei();
while(1) // main loop
{
// do isa i/o
if (QueueUsed() && (~PINB & PIN_DSR)) {
send_isa_byte(MPU401_ReadData()); // send data if there's any in the buffer
}
if (PINB & PIN_CRR) { // isa control input latch is full
MPU401_WriteCommand(recv_isa_byte());
}
if (PINB & PIN_DRR) { // isa data input latch is full
MPU401_WriteData(recv_isa_byte());
}
// do midi i/o
send_midi_byte(); // see if we need to send a byte
/* if (UCSR0A & (1<<RXC0)) { // midi uart rx buffer is full
process_midi_byte();
} */
}
}
static uint8_t mpu401_read(uint16_t addr, void *p)
{
mpu_t *mpu = (mpu_t *)p;
uint8_t ret;
switch (addr & 1)
{
case 0: //Read Data
ret = MPU401_ReadData(mpu);
pclog("Read Data (0x330) %X\n", ret);
break;
case 1: //Read Status
ret = 0x3f; /* Bits 6 and 7 clear */
if (mpu->state.cmd_pending) ret|=STATUS_OUTPUT_NOT_READY;
if (!mpu->queue_used) ret|=STATUS_INPUT_NOT_READY;
pclog("Read Status (0x331) %x\n", ret);
break;
}
/* pclog("MPU401 Read Port %04X, ret %x\n", addr, ret); */
return ret;
}
