First commit. Added an untested Serial Port write driver, which is used for debug.

.gitignore

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+*~
+mtgos
+*.o

Makefile

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+
+all: mtgos
+
+mtgos:
+	make -C kernel
+	mv kernel/mtgos mtgos
+
+clean:
+	make -C kernel clean
+	rm -rf mtgos
+
+.PHONY: all mtgos clean

kernel/Makefile

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+LD = ld
+LDFLAGS = -melf_i386 -Tkernel.ld
+all: hal
+	$(LD) $(LDFLAGS) -o mtgos hal/hal.o
+hal:
+	make -C hal
+clean:
+	make -C hal clean
+
+.PHONY: all hal clean

kernel/hal/Makefile

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+all: x86
+	#Currently only do X86
+	mv x86/hal.o hal.o
+
+x86:
+	make -C x86
+
+clean:
+	rm -rf hal.o
+	make -C x86 clean
+
+.PHONY: all x86 clean

kernel/hal/x86/Makefile

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+SRCS = $(shell find -name '*.cpp' -o -name '*.[cS]')
+OBJS = $(addsuffix .o,$(basename $(SRCS)))
+
+CPP = g++
+CC = gcc
+LD = ld
+ASFLAGS = -m32
+CFLAGS = -m32 -Wall -g -fno-stack-protector -nostdinc -Ic_include/ -ffreestanding -fbuiltin
+CPPFLAGS = -m32 -Wall -g -fno-stack-protector -nostdinc -std=c++14 -Iinclude/ -Ic_include/ -fno-rtti -fno-exceptions -ffreestanding -fbuiltin
+LDFLAGS = -r -melf_i386
+
+hal.o: $(OBJS)
+	$(LD) $(LDFLAGS) -o $@ $^
+
+%.o: %.cpp
+	$(CPP) $(CPPFLAGS) -c -o $@ $^
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c -o $@ $^
+
+%.o: $.S
+	$(CC) $(CFLAGS) -c -o $@ $^
+
+clean:
+	rm -rf $(OBJS)
+
+.PHONY: clean

kernel/hal/x86/boot/boot.S

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+.section multiboot
+#define MB_MAGIC 0x1BADB002
+#define MB_FLAGS 0x0
+#define MB_CHECKSUM -(MB_MAGIC + MB_FLAGS)
+.align 4
+.int MB_MAGIC
+.int MB_FLAGS
+.int MB_CHECKSUM
+.section .text
+.extern init
+.global _start
+_start:
+	mov $kernel_stack, %esp
+	call init
+_stop:
+	cli
+	hlt
+	jmp _stop
+.section .bss
+.space 65536
+kernel_stack:

kernel/hal/x86/c_include/io.h

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+#ifndef _IO_H
+#define _IO_H
+#include <stdint.h>
+static inline void outb(uint16_t port, uint8_t val) {
+	asm volatile("outb %0, %1" : : "a"(val), "Nd"(port));
+}
+static inline void outw(uint16_t port, uint16_t val) {
+	asm volatile("outw %0, %1" : : "a"(val), "Nd"(port));
+}
+static inline void outl(uint16_t port, uint32_t val) {
+	asm volatile("outl %0, %1" : : "a"(val), "Nd"(port));
+}
+static inline uint8_t inb(uint16_t port) {
+	uint8_t ret;
+	asm volatile("inb %1, %0" : "=a"(ret) : "Nd"(port));
+	return ret;
+}
+static inline uint16_t inw(uint16_t port) {
+	uint16_t ret;
+	asm volatile("inw %1, %0" : "=a"(ret) : "Nd"(port));
+	return ret;
+}
+static inline uint32_t inl(uint16_t port) {
+	uint32_t ret;
+	asm volatile("inl %1, %0" : "=a"(ret) : "Nd"(port));
+	return ret;
+}
+static inline void io_wait() {
+	asm volatile("outb %%al, $0x80" : : "a"(0));
+}
+static inline void cli() {
+	asm volatile("cli");
+}
+static inline void sti() {
+	asm volatile("sti");
+}
+
+#endif

kernel/hal/x86/c_include/stdint.h

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+typedef signed char            int8_t;
+typedef signed short           int16_t;
+typedef signed int             int32_t;
+typedef signed long long int   int64_t;
+typedef unsigned char          uint8_t;
+typedef unsigned short         uint16_t;
+typedef unsigned int           uint32_t;
+typedef unsigned long long int uint64_t;

kernel/hal/x86/include/output.hpp

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+#ifndef _OUTPUT_HPP
+#define _OUTPUT_HPP
+namespace MTGosHAL {
+	enum class Base : int {
+		BINARY=2,
+		TERNARY,
+		BASE4,
+		BASE5,
+		BASE6,
+		BASE7,
+		OCTAL,
+		BASE9,
+		DECIMAL,
+		BASE11,
+		BASE12,
+		BASE13,
+		BASE14,
+		BASE15,
+		HEXADECIMAL
+	};
+	/* abstract */ class Output {
+		private:
+			virtual void putChar(char c) { /*ignore*/ };
+			auto puts(const char* s) -> void {
+				int i=0;
+				while(s[i]!='\0')
+					putChar(s[i++]);
+			}
+			int base=10;
+		public:
+			template <typename T>
+			auto operator<<(T output) -> Output & {
+				puts(output); //kernel won't compile if class cannot be converted into string
+				return *this;
+			}
+
+	};
+	template <>
+	auto Output::operator<<<Base>(Base output) -> Output & {
+		base=static_cast<int>(output);
+		return *this;
+	}
+	template <>
+	auto Output::operator<<<int>(int output) -> Output & {
+		const char* chars="0123456789ABCDEF";
+		char buf[33];
+		buf[32]='\0';
+		char* ptr=buf+31;
+		do {
+			*(ptr--)=chars[output%base];
+			output/=base;
+		} while(output && (ptr!=buf));
+		puts(ptr+1);
+		return *this;
+	}
+	template <>
+	auto Output::operator<<<char>(char output) -> Output & {
+		putChar(output);
+		return *this;
+	}
+	template <>
+	auto Output::operator<<<char*>(char* output) -> Output & {
+		puts(output);
+		return *this;
+	}
+}
+#endif

kernel/hal/x86/include/serial.hpp

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+#ifndef _SERIAL_HPP
+#define _SERIAL_HPP
+#include <output.hpp>
+#include <io.h>
+#define SERIAL_IER 1
+#define SERIAL_IIR 2
+#define SERIAL_FCR 2
+#define SERIAL_LCR 3
+#define SERIAL_MCR 4
+#define SERIAL_LSR 5
+#define SERIAL_MSR 6
+namespace MTGosHAL {
+	class Serial: public Output {
+		private:
+			uint16_t port;
+			auto isTransmitEmpty() -> int {
+				return inb(port+SERIAL_LSR)&0x20;
+			}
+			auto putChar(char chr) -> void {
+				while(!isTransmitEmpty());
+				outb(port, chr);
+			}
+			auto puts(const char* s) -> void {
+				int i=0;
+				while(s[i]!='\0')
+					putChar(s[i++]);
+			}
+		public:
+			Serial(uint32_t baud) {
+				port=*((uint16_t*)0x0400);
+				union {
+					uint8_t b[2];
+					uint16_t w;
+				} divisor;
+				divisor.w = 115200/baud;
+				//Turn off interrupts
+				outb(port+SERIAL_IER, 0x00);
+				//Set DLAB-bit
+				outb(port+SERIAL_LCR, 0x80);
+				//Set baud divisor
+				outb(port, divisor.b[0]);
+				outb(port+1, divisor.b[1]);
+				//Set bit count, parity and reset DLAB 
+				outb(port+SERIAL_LCR, 3);
+				//Finish init
+				outb(port+SERIAL_FCR, 0xC7);
+				outb(port+SERIAL_MCR, 0x0B);
+			}
+	};
+}
+
+#endif

kernel/hal/x86/init/init.cpp

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+#include <output.hpp>
+#include <serial.hpp>
+namespace MTGosHAL {
+	Serial serialOUT(115200);
+	void main() {
+		serialOUT=Serial(115200);
+		serialOUT << "This is the debug output of MTGos\n";
+	}
+}
+extern "C" void init() {
+	MTGosHAL::main();
+}
+extern "C" void __cxa_pure_virtual() {
+	for(;;);
+}
+

kernel/kernel.ld

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+ENTRY(_start)
+SECTIONS
+{
+	. = 0x100000;
+	.text : {
+		*(multiboot)
+		*(.text)
+	}
+	.data ALIGN(4096) : {
+		*(.data)
+	}
+	.rodata ALIGN(4096) : {
+		*(.rodata)
+	}
+	.bss ALIGN(4096) : {
+		*(.bss)
+	}
+}