Added logging via serial output.

.gitignore

@@ -3,3 +3,4 @@ isodir/
 myos.iso
 *.o
 myos.bin
+serial.log

buildandrun.sh

@@ -2,4 +2,4 @@
 make clean
 make
 ./builddisc.sh
-qemu-system-i386 -cdrom myos.iso
+qemu-system-i386 -cdrom myos.iso -serial file:serial.log

kernel/arch/i386/io.nim

@@ -5,12 +5,14 @@ type
 
 {.push stackTrace:off.}
 proc outb*(data: IOPacket) =
+  let x = data.value
+  let y = data.port
   asm """
-    outb `data.value` `data.port`
+    "outb %%al, %%dx" : :"a"(`x`), "d"(`y`)
   """
 
 proc inb*(port: uint16): uint =
   asm """
-    inb `port` `result`
+    "inb %%dx, %%al" :"=a"(`result`) :"d"(`port`)
   """
 {.pop.}

kernel/arch/i386/serial.nim

@@ -0,0 +1,26 @@
+import io
+
+const portCOM1 = 0x3f8'u16
+
+proc init*() =
+   io.outb((portCOM1 + 1, 0x00'u8));    # Disable all interrupts
+   io.outb((portCOM1 + 3, 0x80'u8));    # Enable DLAB (set baud rate divisor)
+   io.outb((portCOM1 + 0, 0x03'u8));    # Set divisor to 3 (lo byte) 38400 baud
+   io.outb((portCOM1 + 1, 0x00'u8));    #                  (hi byte)
+   io.outb((portCOM1 + 3, 0x03'u8));    # 8 bits, no parity, one stop bit
+   io.outb((portCOM1 + 2, 0xC7'u8));    # Enable FIFO, clear them, with 14-byte threshold
+   io.outb((portCOM1 + 4, 0x0B'u8));    # IRQs enabled, RTS/DSR set
+
+proc isTransitEmpty(): uint =
+  result = io.inb(portCOM1 + 5) and 0x20'u
+
+proc write*(input: char) =
+  while isTransitEmpty() == 0:
+    discard
+  io.outb((portCOM1, uint8(input)))
+
+proc write*(input: string) =
+  for i in 0 .. input.len - 1:
+    write(input[i])
+  write('\L')
+

kernel/kernel.nim

@@ -1,7 +1,10 @@
-import tty, gdt
+import tty, gdt, irq, serial
 
 proc kernelMain() {.exportc: "kernel_main"}=
+  serial.init()
+  serial.write("Booting OS")
   gdt.gdtInstall()
+  serial.write("GDT installed")
   terminalInitialize()
   terminalWrite("Hello World!\L")
   terminalWrite("MAX_INT:")

makefile

@@ -10,4 +10,4 @@ bootloader:
 	nasm -felf32 kernel/arch/i386/boot.s -o boot.o
 
 clean:
-	rm -r myos.bin nimcache/ boot.o
+	rm -r myos.bin nimcache/ boot.o serial.log