From e5b5905eb3134a409638a5a20462000ef159e1e6 Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@member.fsf.org>
Date: Sat, 7 Apr 2018 07:28:20 +0300
Subject: [PATCH] initial commit

---
 .gitignore      |    6 ++++++
 Makefile        |   44 ++++++++++++++++++++++++++++++++++++++++++++
 pcboot.ld       |   22 ++++++++++++++++++++++
 src/boot/boot.s |   37 +++++++++++++++++++++++++++++++++++++
 src/startup.s   |   11 +++++++++++
 5 files changed, 120 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 pcboot.ld
 create mode 100644 src/boot/boot.s
 create mode 100644 src/startup.s

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..50d3557
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,6 @@
+*.o
+*.swp
+*.d
+*.bin
+test
+*.map
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..d034876
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,44 @@
+csrc = $(wildcard src/*.c) $(wildcard src/libc/*.c)
+ssrc = $(wildcard src/*.s) $(wildcard src/libc/*.s) $(wildcard src/boot/*.s)
+obj = $(csrc:.c=.o) $(ssrc:.s=.o)
+dep = $(obj:.o=.d)
+elf = test
+bin = test.bin
+
+warn = -pedantic -Wall
+dbg = -g
+inc = -Isrc -Isrc/libc
+
+CFLAGS = $(ccarch) $(warn) $(dbg) -nostdinc -fno-builtin $(inc) $(def)
+ASFLAGS = $(asarch) $(dbg) -nostdinc -fno-builtin $(inc)
+LDFLAGS = $(ldarch) -T pcboot.ld -print-gc-sections
+
+
+ifneq ($(shell uname -m), i386)
+	ccarch = -m32
+	asarch = --32
+	ldarch = -m elf_i386
+endif
+
+$(bin): $(elf)
+	objcopy -O binary $< $@
+
+$(elf): $(obj)
+	$(LD) -o $@ $(obj) -Map link.map $(LDFLAGS)
+
+-include $(dep)
+
+%.d: %.c
+	@$(CPP) $(CFLAGS) $< -MM -MT $(@:.d=.o) >$@
+
+.PHONY: clean
+clean:
+	rm -f $(obj) $(bin)
+
+.PHONY: cleandep
+cleandep:
+	rm -f $(dep)
+
+.PHONY: run
+run: $(bin)
+	qemu-system-i386 -fda $(bin)
diff --git a/pcboot.ld b/pcboot.ld
new file mode 100644
index 0000000..f629124
--- /dev/null
+++ b/pcboot.ld
@@ -0,0 +1,22 @@
+OUTPUT_ARCH(i386)
+
+SECTIONS {
+	/* BIOS will load us at 0x7c000h */
+	. = 0x7c000;
+
+	.boot : { * (.boot); }
+	.startup : { * (.startup); }
+	.text : { * (.text); }
+	.rodata : { * (.rodata); }
+	.data : { * (.data); }
+
+	.bss ALIGN(4): {
+		_bss_start = .;
+		* (.bss);
+		. = ALIGN(4);
+		_bss_end = .;
+	}
+	_bss_size = SIZEOF(.bss);
+
+	_mem_start = .;
+}
diff --git a/src/boot/boot.s b/src/boot/boot.s
new file mode 100644
index 0000000..e3fd206
--- /dev/null
+++ b/src/boot/boot.s
@@ -0,0 +1,37 @@
+	.code16
+	.section .boot,"a"
+
+	mov $0x13, %ax
+	int $0x10
+
+	mov $1, %al
+	mov $0x3c8, %dx
+	outb %al, %dx
+	mov $0x3c9, %dx
+	mov $63, %al
+	outb %al, %dx
+	xor %al, %al
+	outb %al, %dx
+	outb %al, %dx
+
+	mov $200, %ebx
+	mov $0x00000101, %eax
+	pushl $0xa000
+	popl %es
+	xor %di, %di
+fill:
+	mov %ebx, %ecx
+	and $1, %ecx
+	jnz 0f
+	rol $16, %eax
+0:	mov $80, %ecx
+	rep stosl
+	dec %ebx
+	jnz fill
+
+	cli
+	hlt
+
+	.org 510
+	.byte 0x55
+	.byte 0xaa
diff --git a/src/startup.s b/src/startup.s
new file mode 100644
index 0000000..8e2c2ea
--- /dev/null
+++ b/src/startup.s
@@ -0,0 +1,11 @@
+	.code32
+	.section .startup
+
+	.extern _bss_start
+	.extern _bss_end
+
+	xor %eax, %eax
+	mov _bss_start, %edi
+	mov _bss_size, %ecx
+	shr $4, %ecx
+	rep stosl
-- 
1.7.10.4