From 1905f3babdc33ad3a684cca4dc35265799a14285 Mon Sep 17 00:00:00 2001
From: Xnoe <xnoe@xnoe.moe>
Date: Tue, 31 Aug 2021 22:50:10 +0100
Subject: [PATCH] kernel32.bin is now written in C, make necessary
 modifications to Makefile, .gitignore, boot32.asm, etc to get this working

---
 .gitignore  |  1 +
 Makefile    | 14 +++++++++++--
 boot32.asm  |  2 +-
 kernel32.c  | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 kernel32.ld |  9 +++++++++
 5 files changed, 81 insertions(+), 3 deletions(-)
 create mode 100644 kernel32.c
 create mode 100644 kernel32.ld

diff --git a/.gitignore b/.gitignore
index ce571f9..d6a02df 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 *.bin
 *.img
 *.sector
+*.o
 img.d/
\ No newline at end of file
diff --git a/Makefile b/Makefile
index 9c3113a..2855285 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,8 @@
-disk.img: boot.sector kernel.bin hello.bin print.bin hello.txt boot32.bin
+
+CFLAGS = -m32 -nostdlib -fno-builtin -fno-exceptions -fno-leading-underscore -fno-pie
+LDFLAGS = 
+
+disk.img: boot.sector kernel.bin hello.bin print.bin hello.txt boot32.bin kernel32.bin
 	dd if=/dev/zero of=disk.img count=43 bs=100k
 	dd if=boot.sector of=disk.img conv=notrunc
 	mount disk.img img.d
@@ -20,4 +24,10 @@ print.bin: print.asm
 	nasm $< -o $@
 
 boot32.bin: boot32.asm
-	nasm $< -o $@
\ No newline at end of file
+	nasm $< -o $@
+
+kernel32.bin: kernel32.ld kernel32.o
+	ld $(LDFLAGS) -T $< -o $@ kernel32.o
+
+kernel32.o: kernel32.c
+	gcc $(CFLAGS) -o $@ -c $<
\ No newline at end of file
diff --git a/boot32.asm b/boot32.asm
index 548537e..b85382d 100644
--- a/boot32.asm
+++ b/boot32.asm
@@ -80,7 +80,7 @@ gdt_code:
 gdt_data:
   dw 0xffff
   dw 0x0
-  db 0x8
+  db 0x0
   db 10010010b
   db 01001111b
   db 0
diff --git a/kernel32.c b/kernel32.c
new file mode 100644
index 0000000..67d6fba
--- /dev/null
+++ b/kernel32.c
@@ -0,0 +1,58 @@
+void clear_screen();
+void set_curpos(int x, int y);
+void print(const char* string);
+
+unsigned char* VMEM_ADDR = (unsigned char*)0xb8000;
+const int TERM_WIDTH = 80;
+const int TERM_HEIGHT = 25;
+
+int cursor_x = 0;
+int cursor_y = 0;
+
+int main() {
+  asm(
+    "mov $0x10, %ax\n"
+    "mov %ax, %ds\n"
+    "mov %ax, %ss\n"
+    "mov $0x90000, %esp"
+  );
+
+  clear_screen();
+  set_curpos(0, 0);
+
+  print("Hello, World!\n\nWe are running XnoeOS Code in C now, Protected Mode has been achieved and everything is working super nicely!\n\nHow wonderful!\n\nNow I just need to hope my print function works properly too~~");
+
+  while (1) {}
+}
+
+void clear_screen()  {
+  for (int i=0; i<TERM_WIDTH*TERM_HEIGHT; i++) {
+    VMEM_ADDR[i*2] = 0x20;
+    VMEM_ADDR[i*2 + 1] = 0x07;
+  }
+}
+
+void set_curpos(int x, int y) {
+  cursor_x = x;
+  cursor_y = y;
+}
+
+void print(const char* string) {
+  int index = 0;
+  char current;
+  while (current=string[index++]) {
+    if (current == '\n') {
+      set_curpos(0, cursor_y+1);
+      continue;
+    }
+
+    int mem_pos = cursor_y * TERM_WIDTH + cursor_x++;
+    VMEM_ADDR[mem_pos*2] = current;
+    VMEM_ADDR[mem_pos*2 + 1] = 0x07;
+
+    if (index == TERM_WIDTH) {
+      cursor_x = 0;
+      cursor_y++;
+    }
+  }
+}
\ No newline at end of file
diff --git a/kernel32.ld b/kernel32.ld
new file mode 100644
index 0000000..014eb3e
--- /dev/null
+++ b/kernel32.ld
@@ -0,0 +1,9 @@
+ENTRY(main)
+OUTPUT_FORMAT(binary)
+OUTPUT_ARCH(i386:i386)
+
+SECTIONS {
+  . = 0x80000;
+
+  .text : { *(.text*) }
+}
\ No newline at end of file