Scolling screen

exception_handler.c

@@ -5,7 +5,8 @@
 __attribute__ ((interrupt))
 void print_handler(struct interrupt_frame *frame, ulong error_code){
 
-    printString("EXCEPTION", RED, BLACK, 0, 6);
+    printStringDetails("EXCEPTION", RED, BLACK, 0, 20);
+    printInt(error_code, RED, BLACK, 11, 20);
     (void) frame;
     (void) error_code;
 }

irq_handler.c

@@ -11,8 +11,10 @@ __attribute__((interrupt)) void keyboard_handler(struct interrupt_frame *frame)
         char c = 0;
         if (inb(0x60) != c) {
                 c = inb(0x60);
-                if (c > 0)
+                if (c > 0){
-                        printChar(c, RED, BLACK, 0, 8);
+                        printChar(c);
+                        printChar('\n');
+                }
         }
         (void)frame;
 }
@@ -21,6 +23,6 @@ __attribute__((interrupt)) void timer_handler(struct interrupt_frame *frame)
 {
         static int timeCnt = 0;
         EOIIrq(IRQ_TIMER);
-        printInt(timeCnt++, RED, BLACK, 0, 9);
+        printInt(timeCnt++, RED, BLACK, 20, VGA_HEIGHT -1 );
         (void)frame;
 }

klibc.c

@@ -0,0 +1,11 @@
+#include "klibc.h"
+
+void *memcpy(void *dst, const void *src, size_t n)
+{
+        char *dstChar       = dst;
+        const char *srcChar = src;
+        for (size_t i = 0; i < n; i++) {
+                *(dstChar++) = *(srcChar++);
+        }
+        return dst;
+}

klibc.h

@@ -0,0 +1,4 @@
+#pragma once
+#include "types.h"
+
+void *memcpy(void *dest, const void *src, size_t n );

main.c

@@ -8,18 +8,6 @@
 #include "types.h"
 #include "vga.h"
 
-char getScancode()
-{
-    char c = 0;
-    do {
-        if (inb(0x60) != c) {
-            c = inb(0x60);
-            if (c > 0)
-                return c;
-        }
-    } while (1);
-}
-
 void cpuid(int code, uint32_t *a, uint32_t *d)
 {
     asm volatile("cpuid" : "=a"(*a), "=d"(*d) : "0"(code) : "ebx", "ecx");
@@ -27,25 +15,23 @@ void cpuid(int code, uint32_t *a, uint32_t *d)
 
 void kmain()
 {
-    const short color = GREEN;
+    initVGA(BLACK, GREEN);
-    clearScreen(BLACK);
+    printString("Setting up IDT\n");
-    printString("Setting up IDT", color, BLACK, 0, 0);
     gdtSetup();
     idtSetup();
-    printString("Setting up IRQ", color, BLACK, 0, 1);
     irqSetup();
     initPit(100);
 
-    printString("Setting up IRQ handlers", color, BLACK, 0, 1);
+    printString("Setting up IRQ handlers\n");
     irqSetRoutine(IRQ_KEYBOARD, keyboard_handler);
     irqSetRoutine(IRQ_TIMER, timer_handler);
-    printString("Enabling HW interrupts", color, BLACK, 0, 2);
+    printString("Enabling HW interrupts\n");
     exceptionSetRoutine(EXCEPTION_DOUBLE_FAULT, print_handler);
     // Enabling the HW interrupts
     asm volatile("sti\n");
     int count = 0;
     while (1) {
-        printInt(count++, color, BLACK, 0, 6);
+        printInt(count++, GREEN, BLACK, 0, VGA_HEIGHT - 1);
     }
-    printString("exiting", color, BLACK, 0, 4);
+    printString("exiting\n");
 }

types.h

@@ -37,3 +37,11 @@ typedef		__s64		int64_t;
 
 typedef enum { FALSE=0, TRUE } bool_t;
 #define NULL ((void*)0)
+
+#if __x86_64__
+typedef unsigned long size_t;
+typedef long ssize_t;
+#else
+typedef unsigned int size_t;
+typedef int ssize_t;
+#endif

vga.c

@@ -1,4 +1,21 @@
 #include "vga.h"
+#include "io.h"
+#include "klibc.h"
+#include "tools.h"
+
+static uint vgaBgColor;
+static uint vgaColor;
+static uint line, col;
+
+int initVGA(uint bgColor, uint color)
+{
+	vgaBgColor = bgColor;
+	vgaColor   = color;
+	clearScreen(bgColor);
+	line = 0;
+	col  = 0;
+	return 0;
+}
 
 void clearScreen(uint bgColor)
 {
@@ -17,7 +34,7 @@ void printInt(int integer, uint color, uint bgColor, int startX, int startY)
 	int x = startX;
 	int i = 0, k = 0;
 	if (integer < 0) {
-		printChar('-', color, bgColor, x++, startY);
+		printCharDetails('-', color, bgColor, x++, startY);
 	}
 	while (integer != 0) {
 		int digit = integer % 10;
@@ -25,24 +42,63 @@ void printInt(int integer, uint color, uint bgColor, int startX, int startY)
 		integer   = integer / 10;
 	}
 	for (k = i - 1; k >= 0; k--) {
-		printChar(num[k] + '0', color, bgColor, x++, startY);
+		printCharDetails(num[k] + '0', color, bgColor, x++, startY);
 	}
 }
 
-void printChar(const char str, uint color, uint bgColor, int startX, int startY)
+void printCharDetails(const char str, uint color, uint bgColor, int startX, int startY)
 {
 	volatile short *vga       = (short *)VGA_ADDR;
 	long int colorAttr        = (bgColor << 4 | (color & 0x0f)) << 8;
-	vga[80 * startY + startX] = colorAttr | str;
+	vga[VGA_WIDTH * startY + startX] = colorAttr | str;
 }
 
-void printString(const char *str, uint color, uint bgColor, int startX, int startY)
+void vgaScrollUp(void)
+{
+	long int colorAttr  = vgaBgColor << 12;
+	volatile short *vga = (short *)VGA_ADDR;
+	for (int i = 1; i < VGA_HEIGHT - 2; i++) { // last line is status line. Do not scroll it
+		memcpy((void *)&vga[VGA_WIDTH * (i - 1)], (void *)&vga[VGA_WIDTH * i],
+		       VGA_WIDTH * sizeof(short));
+	}
+	for(int i = 0; i < VGA_WIDTH; i++){
+		vga[(VGA_HEIGHT - 1) * VGA_WIDTH + i] = colorAttr;
+	}
+}
+
+void printString(const char *str) {
+	while (*str) {
+		printChar(*(str++));
+	}
+
+}
+
+void printChar(const char str)
+{
+	if (str == '\n') {
+		line++;
+		col = 0;
+	}
+	if (col == VGA_WIDTH) {
+		col = 0;
+		line++;
+	}
+	if (line >= VGA_HEIGHT) {
+		vgaScrollUp();
+		line--;
+	}
+	if(str == '\n')
+		return;
+	printCharDetails(str, vgaColor, vgaBgColor, col++, line);
+}
+
+void printStringDetails(const char *str, uint color, uint bgColor, int startX, int startY)
 {
 	volatile short *vga = (short *)VGA_ADDR;
 	int i               = 0;
 	long int colorAttr  = (bgColor << 4 | (color & 0x0f)) << 8;
 	while (*str) {
-		vga[80 * startY + startX + i] = colorAttr | *str;
+		vga[VGA_WIDTH * startY + startX + i] = colorAttr | *str;
 		str++;
 		i++;
 	}

vga.h

@@ -16,7 +16,11 @@
 #define VGA_WIDTH  80
 #define VGA_HEIGHT 25
 
+int initVGA(uint bgColor, uint color);
 void clearScreen(uint bgColor);
 void printInt(int integer, uint color, uint bgColor, int startX, int startY);
-void printChar(char str, uint color, uint bgColor, int startX, int startY);
+void printCharDetails(char str, uint color, uint bgColor, int startX, int startY);
-void printString(const char *str, uint color, uint bgColor, int startX, int startY);
+void printStringDetails(const char *str, uint color, uint bgColor, int startX, int startY);
+void printString(const char *str);
+void printChar(const char str);
+void vgaScrollUp(void);