start work on serial

arch/serial.cc

@@ -1,18 +1,23 @@
 #include "serial.h"
+#include "ioport.h"
 
 Serial::Serial(ComPort port, BaudRate baud_rate, DataBits data_bits,
                StopBits stop_bits, Parity parity)
     : port(port) {
   // initialize FIFO mode, no irqs for sending, irq if first byte was received
+  writeReg(INTERRUPT_ENABLE_REGISTER, RECEIVED_DATA_AVAILABLE);
 
   // line control, select r/w of divisor latch register
   writeReg(LINE_CONTROL_REGISTER, DIVISOR_LATCH_ACCESS_BIT);
 
-  // TODO: Implement here the correct handling of input arguments
-  (void)baud_rate;
-  (void)data_bits;
-  (void)stop_bits;
-  (void)parity;
+  writeReg(DIVISOR_LOW_REGISTER, baud_rate & 0xFF);
+  writeReg(DIVISOR_HIGH_REGISTER, (baud_rate>>8) & 0xFF);
+
+  // also turns DLAB off
+  uint8_t val = parity;
+  val |= stop_bits;
+  val |= data_bits;
+  writeReg(LINE_CONTROL_REGISTER, val);
 
   // FIFO: Enable & clear buffers
   writeReg(FIFO_CONTROL_REGISTER,
@@ -23,19 +28,22 @@ Serial::Serial(ComPort port, BaudRate baud_rate, DataBits data_bits,
 }
 
 void Serial::writeReg(RegisterIndex reg, char out) {
-  // TODO: Implement
-  (void)reg;
-  (void)out;
+  uint16_t addr = port;
+  IOPort iop = IOPort(addr += reg);
+  iop.outb(out);
 }
 
 char Serial::readReg(RegisterIndex reg) {
-  // TODO: Implement
-  (void)reg;
-  return '\0';
+  uint16_t addr = port;
+  IOPort iop = IOPort(addr += reg);
+  return iop.inb();
 }
 
 int Serial::write(char out) {
   // TODO: Implement
-  (void)out;
-  return 0;
+  if(readReg(LINE_STATUS_REGISTER) & TRANSMITTER_EMPTY){
+      writeReg(TRANSMIT_BUFFER_REGISTER, out);
+      return out;
+  }
+  return -1;
 }