From 53801b9baed096e57b40df6147d9ff0f3da0c737 Mon Sep 17 00:00:00 2001
From: Benji Dial <benji3.141@gmail.com>
Date: Sat, 16 May 2020 13:25:46 -0400
Subject: Hello world

---
 src/boot.asm       | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/kernel/link.ld | 15 +++++++++++++++
 src/kernel/main.c  |  7 +++++++
 src/kernel/vga.c   | 14 ++++++++++++++
 src/kernel/vga.h   |  3 +++
 5 files changed, 94 insertions(+)
 create mode 100644 src/boot.asm
 create mode 100644 src/kernel/link.ld
 create mode 100644 src/kernel/main.c
 create mode 100644 src/kernel/vga.c
 create mode 100644 src/kernel/vga.h

(limited to 'src')

diff --git a/src/boot.asm b/src/boot.asm
new file mode 100644
index 0000000..b476581
--- /dev/null
+++ b/src/boot.asm
@@ -0,0 +1,55 @@
+bits 16
+org 0x7c3e
+
+kernel_sectors equ 16
+kernel_segment equ 0x3000
+
+  in al, 0x92
+  or al, 0x02
+  out 0x92, al
+
+  xor ax, ax
+  mov ss, ax
+  mov sp, 0x7ffc
+
+  mov ax, kernel_segment
+  mov es, ax
+  mov ax, 0x0200 + kernel_sectors
+  xor bx, bx
+  mov cx, 0x0002
+  xor dh, dh
+  int 0x13
+
+  cli
+
+  lgdt [gdt]
+
+  mov eax, cr0
+  or al, 0x01
+  mov cr0, eax
+
+  jmp 0x08:pmode
+
+bits 32
+
+pmode:
+  mov ax, 0x10
+  mov ds, ax
+  mov ax, 0x18
+  mov ss, ax
+  mov sp, 0x7ffc
+
+  jmp kernel_segment * 16
+
+gdt:
+  dw .e - .t
+  dd .t
+.t:
+  dq 0x0000_0000_0000_0000
+  dq 0x00c0_9a00_0000_007f
+  dq 0x00c0_9200_0000_007f
+  dq 0x0040_9203_8000_7fff
+.e:
+
+times $$ + 448 - $ db 0
+dw 0xaa55
\ No newline at end of file
diff --git a/src/kernel/link.ld b/src/kernel/link.ld
new file mode 100644
index 0000000..1fcff40
--- /dev/null
+++ b/src/kernel/link.ld
@@ -0,0 +1,15 @@
+OUTPUT_FORMAT(binary)
+OUTPUT_ARCH(i386)
+
+SECTIONS {
+  . = 0x00030000;
+  .entry : {
+    */main.o(.text)
+  }
+  .bin : {
+    *(.text)
+    *(.rodata)
+    *(.data)
+    *(.bss)
+  }
+}
\ No newline at end of file
diff --git a/src/kernel/main.c b/src/kernel/main.c
new file mode 100644
index 0000000..1a8b2f4
--- /dev/null
+++ b/src/kernel/main.c
@@ -0,0 +1,7 @@
+#include <stdint.h>
+#include "vga.h"
+
+void main() {
+  while (1)
+    vga_printsz("Hello! ");
+}
\ No newline at end of file
diff --git a/src/kernel/vga.c b/src/kernel/vga.c
new file mode 100644
index 0000000..d0170c0
--- /dev/null
+++ b/src/kernel/vga.c
@@ -0,0 +1,14 @@
+#include <stdint.h>
+
+#define VGA_START (uint16_t *)0x000b8000
+#define VGA_END (VGA_START + 80 * 25)
+uint16_t *cursor = VGA_START;
+uint16_t color = 0x1f00;
+
+void vga_printsz(uint8_t *sz) {
+  while (*sz) {
+    *(cursor++) = color | *(sz++);
+    if (cursor == VGA_END)
+      cursor = VGA_START;
+  }
+}
\ No newline at end of file
diff --git a/src/kernel/vga.h b/src/kernel/vga.h
new file mode 100644
index 0000000..47ac1fb
--- /dev/null
+++ b/src/kernel/vga.h
@@ -0,0 +1,3 @@
+#include <stdint.h>
+
+void vga_printsz(uint8_t *sz);
\ No newline at end of file
-- 
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