src folder -> source folder; makes merging with dev a bit easier.

source/kernel/tty/kterm.cpp

@@ -0,0 +1,240 @@
+#include "kterm.h"
+static const size_t VGA_WIDTH = 80;
+static const size_t VGA_HEIGHT = 25;
+
+size_t kterm_row;
+size_t kterm_column;
+uint8_t kterm_color;
+uint16_t* kterm_buffer;
+
+
+static inline uint8_t vga_entry_color( enum vga_color fg, enum vga_color bg) {
+    return fg | bg << 4;
+}
+
+static inline uint16_t vga_entry (unsigned char uc, uint8_t color) {
+    return (uint16_t) uc | (uint16_t) color << 8;
+}
+
+void kterm_init () { 
+    kterm_row = 0;
+    kterm_column = 0;
+    kterm_color = vga_entry_color ( VGA_COLOR_LIGHT_GREY , VGA_COLOR_BLACK);
+    kterm_buffer = (uint16_t*) 0xB8000;
+    for (size_t y = 0; y < VGA_HEIGHT; y++ ){
+        for( size_t x = 0; x < VGA_WIDTH; x++){
+            const size_t index = y * VGA_WIDTH + x;
+            kterm_buffer[index] = vga_entry(' ', kterm_color);
+
+        }
+    }
+}
+
+
+void kterm_resetcolor(){
+     kterm_color = vga_entry_color ( VGA_COLOR_LIGHT_GREY , VGA_COLOR_BLACK);
+}
+
+void kterm_setcolor(uint8_t color){
+    kterm_color = color;
+}
+
+void kterm_putat (char c, uint8_t color, size_t x, size_t y ) {
+    const size_t index = y * VGA_WIDTH + x;
+
+    kterm_buffer[index] = vga_entry(c, color);
+
+}
+
+void enable_cursor (uint8_t start_cursor , uint8_t end_cursor ){
+    outb(0x3D4, 0x0A);
+    outb(0x3D5, (inb(0x3D5) & 0xC0) | start_cursor);
+
+    outb(0x3D4, 0x0B);
+    outb(0x3D5, (inb(0x3D5) & 0xE0) | end_cursor);
+}
+
+void disable_cursor() 
+{
+        outb(0x3D4, 0x0A);
+        outb(0x3D5, 0x20);
+}
+
+
+void update_cursor(int x, int y){
+    uint16_t pos = y * VGA_WIDTH + x;
+
+    outb(0x3D4, 0x0F);
+    outb(0x3D5, (uint8_t) (pos & 0xFF));
+    outb(0x3D4, 0x0E);
+    outb(0x3D5, (uint8_t) ((pos >> 8) & 0xFF));
+}
+
+uint16_t get_cursor_position(){
+    uint16_t pos = 0;
+    outb(0x3D4, 0x0F);
+    pos |= inb(0x3D5);
+    outb(0x3D4, 0x0E);
+    pos |= ((uint16_t) inb(0x3D5)) << 8;
+    return pos;
+}
+
+int get_cursor_x (uint16_t cursor_pos) {
+    return cursor_pos % VGA_WIDTH;
+}
+
+int get_cursor_y (uint16_t cursor_pos ) {
+    return cursor_pos / VGA_WIDTH;
+}
+
+
+
+/**
+ *  With the help from:
+ * https://whiteheadsoftware.dev/operating-systems-development-for-dummies/
+ **/ 
+void kterm_scrollup(){
+    size_t i ;
+    for(i=0; i < (VGA_WIDTH * VGA_HEIGHT - VGA_WIDTH); i++)
+        kterm_buffer[i] = kterm_buffer[i+VGA_WIDTH];
+
+    for( i=0; i< VGA_WIDTH; i++)
+        kterm_buffer[(VGA_HEIGHT -1) * VGA_WIDTH + i ] = vga_entry(' ', kterm_color); 
+
+}
+
+void kterm_put (char c) {
+    if(++kterm_column == VGA_WIDTH || c == '\n' ) {
+        update_cursor(kterm_column , kterm_row);
+        kterm_column = 0;
+        if(kterm_row == VGA_HEIGHT-1 ) {       
+            kterm_scrollup();
+        } else {
+            kterm_row ++;
+        }
+    }
+    if ( c == '\r'){
+        kterm_column = 0;
+        return;
+    }
+    
+    if(c == '\n') return;
+    kterm_putat ( c, kterm_color, kterm_column, kterm_row);
+    
+
+}
+
+void kterm_write(const char* data, size_t size) {
+    for(size_t i = 0; i < size; i++){
+        kterm_put(data[i]);
+    }
+}   
+
+void kterm_writestring(const char* data ){
+   // AS_KERNEL();
+    kterm_write(data, strlen(data));
+}
+
+
+static void itoa (char *buf, int base, int d) {
+    char *p = buf;
+    char *p1, *p2;
+    unsigned long ud = d;
+    int divisor = 10;
+    if ( base == 'd' && d < 0){
+        *p++ = '-';
+        buf++;
+        ud = -d;
+    } else if (base == 'x'){
+        divisor = 16;
+    }
+
+    do { 
+        int remainder = ud % divisor;
+
+         *p++ = (remainder < 10 ) ? remainder + '0' : remainder + 'a' -10;
+    } while(ud /= divisor);
+
+    /*terminate buf*/
+    *p =0;
+    p1 = buf;
+    p2 = p -1;
+
+    while (p1 < p2)
+    {
+        char tmp = *p1;
+        *p1 = *p2;
+        *p2 = tmp;
+        p1++;
+        p2--;
+
+    }
+
+}
+
+
+/**
+ * @brief For now this will not only write to VGA memory but also write to serial 
+ * 
+ * @param format 
+ * @param ... 
+ */
+void printf ( const char *format, ...) {
+    
+    char **arg = (char **)&format;
+    int c;
+    char buf[20];
+
+    arg++;
+    
+    while ((c = *format++) != 0){
+        if( c != '%')
+            kterm_put(c);
+        else{
+            char *p, *p2;
+            int pad0 = 0, pad = 0;
+
+            c = *format++;
+            if(c =='0'){
+                pad0 = 1;
+                c = *format++;
+            }
+
+            if ( c >= '0' && c <= '9'){
+                pad = c - '0';
+                c = *format++;
+            }
+
+            switch (c)
+            {
+            case 'd':
+             
+            case 'u':
+            case 'x':
+                itoa(buf, c, *((int *) arg++));
+
+                p = buf;
+                goto string;
+                break;
+            
+            case 's':
+                p = *arg++;
+                if(!p)
+                    p = "(null)";
+                
+                string: 
+                    for (p2 = p; *p2; p2++);
+                    for (; p2 < p + pad; p2++)
+                        kterm_put(pad0 ? '0': ' ');
+                    while (*p)
+                        kterm_put(*p++);
+                    break;
+
+
+            default:
+                kterm_put(*((int *)arg++));
+                break;
+            }
+        }
+    }
+}

source/kernel/tty/kterm.h

@@ -0,0 +1,46 @@
+#pragma once 
+#include <stdint.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "../drivers/VGA/colors.h"
+#include "../drivers/IO/io.h"
+
+extern "C"{
+    #include "./../../libc/include/string.h"
+}
+
+void kterm_init();
+
+/* Kernel terminal - Colour functions*/
+void kterm_resetcolor();
+void kterm_setcolor(uint8_t);
+
+/* Kernel terminal - Printing function */
+void kterm_putat(char, uint8_t, size_t, size_t);
+void kterm_put(char);
+void kterm_write(const char*, size_t);
+void kterm_writestring(const char*);
+void kterm_scrollup();
+
+
+/* Kernel terminal - Cursor functions */
+void enable_cursor (uint8_t start_cursor , uint8_t end_cursor );
+void disable_cursor();
+void update_cursor(int x, int y);
+uint16_t get_cursor_position();
+int get_cursor_x (uint16_t cursor_pos);
+int get_cursor_y (uint16_t cursor_pos);
+
+
+void printf ( const char *format, ...);
+
+//static void itoa (char *buf, int base, int d);
+
+#define KernelTag "[Kernel]: "
+#define AS_KERNEL() (  kterm_setcolor(VGA_COLOR_LIGHT_BLUE),\
+                       kterm_write(KernelTag, 10 ), \
+                       kterm_resetcolor())
+
+