From c79e957f387a47905131d35b002fa3091b243a38 Mon Sep 17 00:00:00 2001
From: Gitea <gitea@fake.local>
Date: Fri, 18 Dec 2020 12:38:32 -0600
Subject: [PATCH] we got the gdt working!

---
 arch/i386/gdt.c                 |  4 ++-
 arch/i386/gdt.h                 |  2 +-
 arch/i386/{gdt.S => gdt_load.S} | 18 +++++--------
 arch/i386/init.c                | 46 +++++++++++++++++++++++++++++----
 arch/i386/make.config           |  2 +-
 include/kernel/init.h           |  3 +++
 6 files changed, 56 insertions(+), 19 deletions(-)
 rename arch/i386/{gdt.S => gdt_load.S} (70%)

diff --git a/arch/i386/gdt.c b/arch/i386/gdt.c
index b3f9168..8d87c15 100644
--- a/arch/i386/gdt.c
+++ b/arch/i386/gdt.c
@@ -1,3 +1,5 @@
+#include "gdt.h"
+
 void encode_gdt_entry(unsigned short int * target, struct GDT source) {
   if((source.limit > 65536) && ((source.limit & 0xFFF) != 0xFFF)) {
     /* This needs to error out. */
@@ -25,4 +27,4 @@ void encode_gdt_entry(unsigned short int * target, struct GDT source) {
 
   /* Encode type */
   target[5] = source.type;
-}
+}
\ No newline at end of file
diff --git a/arch/i386/gdt.h b/arch/i386/gdt.h
index b8581df..0c1315d 100644
--- a/arch/i386/gdt.h
+++ b/arch/i386/gdt.h
@@ -8,7 +8,7 @@ struct GDT {
 };
 
 void encode_gdt_entry(unsigned short int *, struct GDT);
-extern void set_gdt(void);
+extern void set_gdt(unsigned short int[], int);
 extern void reload_segments(void);
 
 #endif
diff --git a/arch/i386/gdt.S b/arch/i386/gdt_load.S
similarity index 70%
rename from arch/i386/gdt.S
rename to arch/i386/gdt_load.S
index 1a9740a..bf21b63 100644
--- a/arch/i386/gdt.S
+++ b/arch/i386/gdt_load.S
@@ -6,24 +6,20 @@ gdtr:
 	.int 0
 
 set_gdt:
-	.fnstart
+	.func set_gdt
 	mov 4(%esp), %eax
-	mov %eax, 2($gdtr)
+	mov %eax, gdtr+2
 	mov 8(%esp), %ax
-	mov %ax, $gdtr
-	lgdt $gdtr
+	mov %ax, gdtr
+	lgdt gdtr
 	ret
-	.fnend
+	.endfunc
 
 	.globl reload_segments
 	.type reload_segments,%function
 	
 reload_segments:
-	.fnstart
-	jmp 0x08:reload_CS
-	.fnend
-	
-reload_CS:
+	.func reload_segments
 	mov 0x10, %ax
 	mov %ax, %ds
 	mov %ax, %es
@@ -31,4 +27,4 @@ reload_CS:
 	mov %ax, %gs
 	mov %ax, %ss
 	ret
-	
+	.endfunc
diff --git a/arch/i386/init.c b/arch/i386/init.c
index 454e159..9b966b3 100755
--- a/arch/i386/init.c
+++ b/arch/i386/init.c
@@ -3,6 +3,10 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
+#include <sys/io.h>
+#include "gdt.h"
+
+int tss[16][2];
 
 int test_libc(void) {
   int failed = 0;
@@ -10,12 +14,8 @@ int test_libc(void) {
   printf("==Testing stdio.h==\n");
 
   printf("printf(\"%%d\", 10): %d (expected 10)\n", 10);
-  printf("printf(\"%%d\", -10): %d (expected -10)\n", -10);
-  printf("printf(\"%%i\", 10): %d (expected 10)\n", 10);
-  printf("printf(\"%%o\", 014): %o (expected 14)\n", 014);
   printf("printf(\"%%o\", 14): %o (expected 16)\n", 14);
   printf("printf(\"%%u\", 10): %u (expected 10)\n", 10);
-  printf("printf(\"%%x\", 0xC9A): %x (expected c9a)\n", 0xC9A);
   printf("printf(\"%%x\", 26): %x (expected 1a)\n", 26);
   printf("printf(\"%%X\", 0xC9A): %x (expected C9A)\n", 0xC9A);
   printf("printf(\"%%p\", &i): %p (expected 0x[hex])\n", &failed);
@@ -95,12 +95,48 @@ int test_libc(void) {
   }
 
   printf("Tests failed: %d\n", failed);
-  printf("One final test: If you can see this, the TTY can scroll.");
 
   return failed;
 }
 
+void NMI_disable(void) {
+  outb(0x70, inb(0x70) | 0x80);
+}
+
+void NMI_enable(void) {
+  outb(0x70, inb(0x70) & 0x7F);
+}
+
+void A20_enable(void) {
+  unsigned short int a = inb(0x92);
+  if((a & 2) != 0) {
+    return;
+  }
+  a |= 2;
+  outb(a, 0x92);
+}
+
+void setup_gdt(void) {
+  struct GDT gdt[4];
+
+  gdt[0].base = 0; gdt[0].limit = 0; gdt[0].type = 0;
+  gdt[1].base = 0; gdt[1].limit = 0xFFFFFFFF; gdt[1].type = 0x9A;
+  gdt[2].base = 0; gdt[2].limit = 0xFFFFFFFF; gdt[2].type = 0x92;
+  gdt[3].base = (unsigned int) tss; gdt[3].limit=sizeof(tss); gdt[3].type = 0x89;
+
+  unsigned short int GDT[4];
+  encode_gdt_entry(&GDT[0], gdt[0]);
+  encode_gdt_entry(&GDT[1], gdt[1]);
+  encode_gdt_entry(&GDT[2], gdt[2]);
+  encode_gdt_entry(&GDT[3], gdt[3]);
+
+  set_gdt(GDT, sizeof(GDT));
+}
+
 int init(void) {
+  NMI_disable();
+  A20_enable();
+  setup_gdt();
   printf("Fenix Dev Pre-release v0.0.3\n");
   return test_libc();
 }
diff --git a/arch/i386/make.config b/arch/i386/make.config
index e6455c7..377267d 100755
--- a/arch/i386/make.config
+++ b/arch/i386/make.config
@@ -3,4 +3,4 @@ KERNEL_ARCH_CPPFLAGS=
 KERNEL_ARCH_LDFLAGS=
 KERNEL_ARCH_LIBS=
 
-KERNEL_ARCH_OBJS=$(ARCHDIR)/boot.o $(ARCHDIR)/tty.o $(ARCHDIR)/init.o $(ARCHDIR)/cmos.o
\ No newline at end of file
+KERNEL_ARCH_OBJS=$(ARCHDIR)/boot.o $(ARCHDIR)/tty.o $(ARCHDIR)/init.o $(ARCHDIR)/cmos.o $(ARCHDIR)/gdt.o $(ARCHDIR)/gdt_load.o
\ No newline at end of file
diff --git a/include/kernel/init.h b/include/kernel/init.h
index b411cd7..2fe7138 100755
--- a/include/kernel/init.h
+++ b/include/kernel/init.h
@@ -3,6 +3,9 @@
 
 #include <stdio.h>
 
+extern int tss[16][2];
+extern unsigned short int * GDT;
+
 int test_libc(void);
 int init(void);