From 10b8fdc33f1d452e066ea90f6b411a17c1744d08 Mon Sep 17 00:00:00 2001
From: Gregory Bowne <gbowne144@gmail.com>
Date: Tue, 13 May 2025 10:44:10 -0700
Subject: [PATCH] adding and fixing some missing things and some undefined

---
 bootloader/boot.bin | Bin 0 -> 512 bytes
 kernel/debug.c      |   0
 kernel/debug.h      |   0
 kernel/fs.c         |   0
 kernel/fs.h         |   0
 kernel/gdt.asm      |   0
 kernel/gdt.c        |   0
 kernel/gdt.h        |   0
 kernel/heap.c       |   0
 kernel/heap.h       |   0
 kernel/idt.c        |  66 ++++++++++++++++++++++++++++++++++++++++--
 kernel/irq.c        |   0
 kernel/irq.h        |   0
 kernel/isr.asm      |  68 +++++++++++++++++++++++++++++++++++++-------
 kernel/isr.h        |   0
 kernel/keyboard.c   |  53 ++++++++++++++++++++++++++++++++++
 kernel/keyboard.h   |   7 +++++
 kernel/kmalloc.c    |   0
 kernel/kmalloc.h    |   0
 kernel/multiboot.h  |   0
 kernel/paging.c     |   6 ++--
 kernel/serial.c     |  37 ++++++++++++++++++------
 kernel/serial.h     |   6 ++--
 kernel/syscalls.c   |   0
 kernel/syscalls.h   |   0
 kernel/terminal.c   |  52 +++++++++++++++++++++++++++++++--
 kernel/terminal.h   |   1 +
 kernel/threading.c  |   0
 kernel/threading.h  |   0
 kernel/timer.c      |   0
 kernel/timer.h      |   0
 kernel/vga.c        |   0
 kernel/vga.h        |   0
 33 files changed, 267 insertions(+), 29 deletions(-)
 create mode 100644 bootloader/boot.bin
 create mode 100644 kernel/debug.c
 create mode 100644 kernel/debug.h
 create mode 100644 kernel/fs.c
 create mode 100644 kernel/fs.h
 create mode 100644 kernel/gdt.asm
 create mode 100644 kernel/gdt.c
 create mode 100644 kernel/gdt.h
 create mode 100644 kernel/heap.c
 create mode 100644 kernel/heap.h
 create mode 100644 kernel/irq.c
 create mode 100644 kernel/irq.h
 create mode 100644 kernel/isr.h
 create mode 100644 kernel/keyboard.c
 create mode 100644 kernel/keyboard.h
 create mode 100644 kernel/kmalloc.c
 create mode 100644 kernel/kmalloc.h
 create mode 100644 kernel/multiboot.h
 create mode 100644 kernel/syscalls.c
 create mode 100644 kernel/syscalls.h
 create mode 100644 kernel/threading.c
 create mode 100644 kernel/threading.h
 create mode 100644 kernel/timer.c
 create mode 100644 kernel/timer.h
 create mode 100644 kernel/vga.c
 create mode 100644 kernel/vga.h

diff --git a/bootloader/boot.bin b/bootloader/boot.bin
new file mode 100644
index 0000000000000000000000000000000000000000..ed8cf0545ddf94c3ed31bb66464860b9e8daef2b
GIT binary patch
literal 512
zcmexmc%bh_-+{ghdl+h7ura*QV0fX;@MIDX)3Zs38KB_*e;{Mlc?K{&={$ohgG>zr
z13#mfNzLJ3{0axsnoltDD;;<hP{YBHwnKmcY~X{w7a&6!I2m3sFbFVkzziFu2T=%w
Gt^xoXtSC+Z

literal 0
HcmV?d00001

diff --git a/kernel/debug.c b/kernel/debug.c
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/debug.h b/kernel/debug.h
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/fs.c b/kernel/fs.c
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/fs.h b/kernel/fs.h
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/gdt.asm b/kernel/gdt.asm
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/gdt.c b/kernel/gdt.c
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/gdt.h b/kernel/gdt.h
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/heap.c b/kernel/heap.c
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/heap.h b/kernel/heap.h
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/idt.c b/kernel/idt.c
index 434982e..2bb5af3 100644
--- a/kernel/idt.c
+++ b/kernel/idt.c
@@ -8,7 +8,37 @@ idt_ptr_t idt_ptr;
 
 // External assembly stubs for ISRs (provided below)
 extern void isr0();
+extern void isr1();
+extern void isr2();
+extern void isr3();
+extern void isr4();
+extern void isr5();
+extern void isr6();
+extern void isr7();
+extern void isr8();
+extern void isr9();
+extern void isr10();
+extern void isr11();
+extern void isr12();
 extern void isr13();
+extern void isr14();
+extern void isr15();
+extern void isr16();
+extern void isr17();
+extern void isr18();
+extern void isr19();
+extern void isr20();
+extern void isr21();
+extern void isr22();
+extern void isr23();
+extern void isr24();
+extern void isr25();
+extern void isr26();
+extern void isr27();
+extern void isr28();
+extern void isr29();
+extern void isr30();
+extern void isr31();
 extern void isr_default();
 
 // Helper to set an IDT gate
@@ -36,8 +66,40 @@ void idt_init() {
     }
 
     // Set specific handlers
-    idt_set_gate(0, (uint32_t)isr0);   // Divide by zero
-    idt_set_gate(13, (uint32_t)isr13); // General protection fault
+    // Assign CPU exception handlers
+    idt_set_gate(0, (uint32_t)isr0);
+    idt_set_gate(1, (uint32_t)isr1);
+    idt_set_gate(2, (uint32_t)isr2);
+    idt_set_gate(3, (uint32_t)isr3);
+    idt_set_gate(4, (uint32_t)isr4);
+    idt_set_gate(5, (uint32_t)isr5);
+    idt_set_gate(6, (uint32_t)isr6);
+    idt_set_gate(7, (uint32_t)isr7);
+    idt_set_gate(8, (uint32_t)isr8);
+    idt_set_gate(9, (uint32_t)isr9);
+    idt_set_gate(10, (uint32_t)isr10);
+    idt_set_gate(11, (uint32_t)isr11);
+    idt_set_gate(12, (uint32_t)isr12);
+    idt_set_gate(13, (uint32_t)isr13);
+    idt_set_gate(14, (uint32_t)isr14);
+    idt_set_gate(15, (uint32_t)isr15);
+    idt_set_gate(16, (uint32_t)isr16);
+    idt_set_gate(17, (uint32_t)isr17);
+    idt_set_gate(18, (uint32_t)isr18);
+    idt_set_gate(19, (uint32_t)isr19);
+    idt_set_gate(20, (uint32_t)isr20);
+    idt_set_gate(21, (uint32_t)isr21);
+    idt_set_gate(22, (uint32_t)isr22);
+    idt_set_gate(23, (uint32_t)isr23);
+    idt_set_gate(24, (uint32_t)isr24);
+    idt_set_gate(25, (uint32_t)isr25);
+    idt_set_gate(26, (uint32_t)isr26);
+    idt_set_gate(27, (uint32_t)isr27);
+    idt_set_gate(28, (uint32_t)isr28);
+    idt_set_gate(29, (uint32_t)isr29);
+    idt_set_gate(30, (uint32_t)isr30);
+    idt_set_gate(31, (uint32_t)isr31);
+
 
     idt_load();
 }
diff --git a/kernel/irq.c b/kernel/irq.c
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/irq.h b/kernel/irq.h
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/isr.asm b/kernel/isr.asm
index 250fd50..2137e7b 100644
--- a/kernel/isr.asm
+++ b/kernel/isr.asm
@@ -1,29 +1,77 @@
-; isr.asm
 [BITS 32]
-[GLOBAL isr0, isr13, isr_default]
+[GLOBAL isr0, isr1, isr2, isr3, isr4, isr5, isr6, isr7, isr8, isr9]
+[GLOBAL isr10, isr11, isr12, isr13, isr14, isr15, isr16, isr17, isr18, isr19]
+[GLOBAL isr20, isr21, isr22, isr23, isr24, isr25, isr26, isr27, isr28, isr29]
+[GLOBAL isr30, isr31, isr_default]
 
-isr0:
+%macro ISR_NOERR 1
+isr%1:
     cli
-    push byte 0
-    push byte 0
+    push dword 0         ; Dummy error code
+    push dword %1        ; Interrupt number
     call isr_handler
     add esp, 8
     sti
     iret
+%endmacro
 
-isr13:
+%macro ISR_ERR 1
+isr%1:
     cli
-    push byte 13
-    push byte 0
+    push dword %1        ; Interrupt number
     call isr_handler
     add esp, 8
     sti
     iret
+%endmacro
 
+; ISR 0–7: No error code
+ISR_NOERR 0
+ISR_NOERR 1
+ISR_NOERR 2
+ISR_NOERR 3
+ISR_NOERR 4
+ISR_NOERR 5
+ISR_NOERR 6
+ISR_NOERR 7
+
+; ISR 8–14: Error code pushed automatically
+ISR_ERR 8
+ISR_NOERR 9           ; Coprocessor Segment Overrun (obsolete, no error code)
+ISR_ERR 10
+ISR_ERR 11
+ISR_ERR 12
+ISR_ERR 13
+ISR_ERR 14
+
+; ISR 15 is reserved
+ISR_NOERR 15
+
+; ISR 16–19 (FPU, Alignment Check, etc.)
+ISR_NOERR 16
+ISR_ERR 17
+ISR_NOERR 18
+ISR_NOERR 19
+
+; ISR 20–31 (reserved or future use)
+ISR_NOERR 20
+ISR_NOERR 21
+ISR_NOERR 22
+ISR_NOERR 23
+ISR_NOERR 24
+ISR_NOERR 25
+ISR_NOERR 26
+ISR_NOERR 27
+ISR_NOERR 28
+ISR_NOERR 29
+ISR_NOERR 30
+ISR_NOERR 31
+
+; Fallback handler
 isr_default:
     cli
-    push byte 255
-    push byte 0
+    push dword 255
+    push dword 0
     call isr_handler
     add esp, 8
     sti
diff --git a/kernel/isr.h b/kernel/isr.h
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/keyboard.c b/kernel/keyboard.c
new file mode 100644
index 0000000..e1c6cd9
--- /dev/null
+++ b/kernel/keyboard.c
@@ -0,0 +1,53 @@
+#include "keyboard.h"
+#include "io.h"
+#include "isr.h"
+#include "terminal.h"
+
+#define KEYBOARD_DATA_PORT 0x60
+
+static char key_buffer[256];
+static uint8_t buffer_index = 0;
+
+// Basic US QWERTY keymap (scancode to ASCII)
+static const char scancode_map[128] = {
+    0,  27, '1', '2', '3', '4', '5', '6', '7', '8', // 0x00 - 0x09
+   '9', '0', '-', '=', '\b', '\t', 'q', 'w', 'e', 'r', // 0x0A - 0x13
+   't', 'y', 'z', 'u', 'i', 'o', 'p', '[', ']', '\n', // 0x14 - 0x1D
+    0, 'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', // 0x1E - 0x27
+   ';', '\'', '`', 0, '\\', 'y', 'x', 'c', 'v', 'b', // 0x28 - 0x31
+   'n', 'm', ',', '.', '/', 0, '*', 0, ' ', 0,      // 0x32 - 0x3B
+    // rest can be filled as needed
+};
+
+// Interrupt handler for IRQ1
+void keyboard_callback() {
+    uint8_t scancode = inb(KEYBOARD_DATA_PORT);
+
+    // Ignore key releases (scancodes with high bit set)
+    if (scancode & 0x80)
+        return;
+
+    char c = scancode_map[scancode];
+    if (c && buffer_index < sizeof(key_buffer)) {
+        key_buffer[buffer_index++] = c;
+        terminal_putchar(c); // Echo to terminal (optional)
+    }
+}
+
+void keyboard_init() {
+    register_interrupt_handler(33, keyboard_callback); // IRQ1 = int 33 (0x21)
+}
+
+// Blocking read (returns one char)
+char keyboard_get_char() {
+    while (buffer_index == 0);
+    char c = key_buffer[0];
+
+    // Shift buffer left
+    for (uint8_t i = 1; i < buffer_index; i++) {
+        key_buffer[i - 1] = key_buffer[i];
+    }
+    buffer_index--;
+
+    return c;
+}
diff --git a/kernel/keyboard.h b/kernel/keyboard.h
new file mode 100644
index 0000000..4f269ed
--- /dev/null
+++ b/kernel/keyboard.h
@@ -0,0 +1,7 @@
+#ifndef KEYBOARD_H
+#define KEYBOARD_H
+
+void keyboard_init(void);
+char keyboard_get_char(void);  // Blocking read from buffer
+
+#endif
diff --git a/kernel/kmalloc.c b/kernel/kmalloc.c
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/kmalloc.h b/kernel/kmalloc.h
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/multiboot.h b/kernel/multiboot.h
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/paging.c b/kernel/paging.c
index ac352b6..6028a69 100644
--- a/kernel/paging.c
+++ b/kernel/paging.c
@@ -8,13 +8,13 @@ page_table_entry_t *page_table = (page_table_entry_t *)0x101000; // Located righ
 void set_page_directory(page_directory_entry_t *dir) {
     for (int i = 0; i < PAGE_DIRECTORY_SIZE; i++) {
         // Set up a page directory entry with identity mapping
-        dir[i].present = 1;
-        dir[i].rw = 1;           // Read/Write
+        dir[i].present = 9;
+        dir[i].rw = 0;           // Read/Write
         dir[i].user = 0;         // Kernel mode
         dir[i].write_through = 0;
         dir[i].cache_disabled = 0;
         dir[i].accessed = 0;
-        dir[i].frame = (uint32_t)&page_table[i] >> 12;  // Page table frame address
+        dir[0].frame = (uint32_t)page_table >> 12;
     }
 }
 
diff --git a/kernel/serial.c b/kernel/serial.c
index 9d1cef6..f1036c8 100644
--- a/kernel/serial.c
+++ b/kernel/serial.c
@@ -1,20 +1,39 @@
 #include "io.h"
+#include "serial.h"
 
 #define COM1 0x3F8
+#define COM2 0x2F8
+#define COM3 0x3E8
+#define COM4 0x2E8
+
+void serial_init_port(uint16_t port) {
+    outb(port + 1, 0x00);
+    outb(port + 3, 0x80);
+    outb(port + 0, 0x03);
+    outb(port + 1, 0x00);
+    outb(port + 3, 0x03);
+    outb(port + 2, 0xC7);
+    outb(port + 4, 0x0B);
+}
 
 void serial_init(void) {
-    outb(COM1 + 1, 0x00); // Disable interrupts
-    outb(COM1 + 3, 0x80); // Enable DLAB
-    outb(COM1 + 0, 0x03); // Set baud rate to 38400
-    outb(COM1 + 1, 0x00);
-    outb(COM1 + 3, 0x03); // 8 bits, no parity, one stop bit
-    outb(COM1 + 2, 0xC7); // Enable FIFO, clear, 14-byte threshold
-    outb(COM1 + 4, 0x0B); // IRQs enabled, RTS/DSR set
+    serial_init_port(COM1);
+    serial_init_port(COM2);
+    serial_init_port(COM3);
+    serial_init_port(COM4);
+}
+
+void serial_write_char(char c) {
+    while (!(inb(COM1 + 5) & 0x20));
+    outb(COM1, c);
 }
 
 void serial_write(const char *str) {
     while (*str) {
-        while (!(inb(COM1 + 5) & 0x20)); // Wait for the transmitter holding register to be empty
-        outb(COM1, *str++);
+        serial_write_char(*str++);
     }
 }
+
+void serial_write_string(const char* str) {
+    serial_write(str);
+}
diff --git a/kernel/serial.h b/kernel/serial.h
index 7c0fa3b..7ba444f 100644
--- a/kernel/serial.h
+++ b/kernel/serial.h
@@ -4,7 +4,9 @@
 #include <stdint.h>
 
 void serial_init(void);
-void serial_write(char c);
+void serial_init_port(uint16_t port);
+void serial_write_char(char c);
+void serial_write(const char *str);
 void serial_write_string(const char *str);
 
-#endif
+#endif
\ No newline at end of file
diff --git a/kernel/syscalls.c b/kernel/syscalls.c
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/syscalls.h b/kernel/syscalls.h
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/terminal.c b/kernel/terminal.c
index 0978c26..40d0265 100644
--- a/kernel/terminal.c
+++ b/kernel/terminal.c
@@ -1,5 +1,6 @@
 #include <stdint.h>
 #include "io.h"
+#include "terminal.h"
 
 #define VGA_ADDRESS 0xB8000
 #define VGA_WIDTH 80
@@ -9,6 +10,7 @@
 static uint16_t* const vga_buffer = (uint16_t*) VGA_ADDRESS;
 static uint8_t cursor_x = 0;
 static uint8_t cursor_y = 0;
+static uint8_t current_color = WHITE_ON_BLACK;
 
 static uint16_t vga_entry(char c, uint8_t color) {
     return (uint16_t) color << 8 | (uint8_t) c;
@@ -18,20 +20,35 @@ void terminal_initialize(void) {
     for (uint16_t y = 0; y < VGA_HEIGHT; y++) {
         for (uint16_t x = 0; x < VGA_WIDTH; x++) {
             const size_t index = y * VGA_WIDTH + x;
-            vga_buffer[index] = vga_entry(' ', WHITE_ON_BLACK);
+            vga_buffer[index] = vga_entry(' ', current_color);
         }
     }
     cursor_x = 0;
     cursor_y = 0;
+    update_cursor(); // Optional: good idea to reset position
 }
 
 void terminal_putchar(char c) {
+    // Handle backspace
+    if (c == '\b') {
+        if (cursor_x > 0) {
+            cursor_x--;
+        } else if (cursor_y > 0) {
+            cursor_y--;
+            cursor_x = VGA_WIDTH - 1;
+        }
+        vga_buffer[cursor_y * VGA_WIDTH + cursor_x] = vga_entry(' ', current_color);
+        update_cursor(); // Optional, if you add cursor updating
+        return;
+    }
+
+    // Handle newline
     if (c == '\n') {
         cursor_x = 0;
         cursor_y++;
     } else {
         const size_t index = cursor_y * VGA_WIDTH + cursor_x;
-        vga_buffer[index] = vga_entry(c, WHITE_ON_BLACK);
+        vga_buffer[index] = vga_entry(c, current_color);
         cursor_x++;
         if (cursor_x >= VGA_WIDTH) {
             cursor_x = 0;
@@ -49,15 +66,44 @@ void terminal_putchar(char c) {
 
         // Clear the last line
         for (uint16_t x = 0; x < VGA_WIDTH; x++) {
-            vga_buffer[(VGA_HEIGHT - 1) * VGA_WIDTH + x] = vga_entry(' ', WHITE_ON_BLACK);
+            vga_buffer[(VGA_HEIGHT - 1) * VGA_WIDTH + x] = vga_entry(' ', current_color);
         }
 
         cursor_y = VGA_HEIGHT - 1;
     }
+
+    update_cursor(); // Optional, if you want the hardware cursor to follow
 }
 
+
 void terminal_write(const char* str) {
     for (size_t i = 0; str[i] != '\0'; i++) {
         terminal_putchar(str[i]);
     }
 }
+
+void terminal_setcolor(uint8_t color)
+{
+    current_color = color;
+}
+
+void terminal_clear(void) {
+    for (uint16_t y = 0; y < VGA_HEIGHT; y++) {
+        for (uint16_t x = 0; x < VGA_WIDTH; x++) {
+            const size_t index = y * VGA_WIDTH + x;
+            vga_buffer[index] = vga_entry(' ', current_color);
+        }
+    }
+    cursor_x = 0;
+    cursor_y = 0;
+    update_cursor();
+}
+
+static void update_cursor() {
+    uint16_t pos = cursor_y * VGA_WIDTH + cursor_x;
+
+    outb(0x3D4, 0x0F);
+    outb(0x3D5, (uint8_t)(pos & 0xFF));
+    outb(0x3D4, 0x0E);
+    outb(0x3D5, (uint8_t)((pos >> 8) & 0xFF));
+}
diff --git a/kernel/terminal.h b/kernel/terminal.h
index 28dd3c4..ce28bc3 100644
--- a/kernel/terminal.h
+++ b/kernel/terminal.h
@@ -7,5 +7,6 @@ void terminal_initialize(void);
 void terminal_putchar(char c);
 void terminal_write(const char *str);
 void terminal_setcolor(uint8_t color);
+void terminal_clear(void);
 
 #endif
diff --git a/kernel/threading.c b/kernel/threading.c
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/threading.h b/kernel/threading.h
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/timer.c b/kernel/timer.c
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/timer.h b/kernel/timer.h
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/vga.c b/kernel/vga.c
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/vga.h b/kernel/vga.h
new file mode 100644
index 0000000..e69de29