Finished VGA driver and implemented stdio.h (printf and puts)

src/kernel/drivers/vga.c

@@ -3,22 +3,22 @@
 
 static uint8_t current_color = VGA_COLOR_DEFAULT;
 
-void set_char(int x, int y, char c){
+void vga_set_char(int x, int y, char c){
     VGA_MEMORY[(x+y*VGA_WIDTH)*2] = c;
 }
 
-void set_color(int x, int y, uint8_t color){
+void vga_set_color(int x, int y, uint8_t color){
     VGA_MEMORY[(x+y*VGA_WIDTH)*2+1] = color;
 }
 
-void set_cursor(int offset){
+void vga_set_cursor(int offset){
     i686_outb(VGA_PORT_CTRL, 14);
     i686_outb(VGA_PORT_DATA, (uint8_t)(offset >> 8));
     i686_outb(VGA_PORT_CTRL, 15);
     i686_outb(VGA_PORT_DATA, (uint8_t)(offset & 0xff));
 }
 
-int get_cursor(){
+int vga_get_cursor(){
     i686_outb(VGA_PORT_CTRL, 14);
     int offset = i686_inb(VGA_PORT_DATA) << 8; // High byte
     i686_outb(VGA_PORT_CTRL, 15);
@@ -34,7 +34,7 @@ static int get_offset_x(int offset){
     return (offset - (get_offset_y(offset)*VGA_WIDTH));
 }
 
-int print_char(char c, int x, int y){
+int vga_print_char(char c, int x, int y){
     if(x >= VGA_WIDTH || y >= VGA_HEIGHT){ // Incorrect coords
         VGA_MEMORY[2*VGA_WIDTH*VGA_HEIGHT-2] = 'E';
         VGA_MEMORY[2*VGA_WIDTH*VGA_HEIGHT-1] = VGA_COLOR_BG_RED || VGA_COLOR_FG_BLACK;
@@ -43,7 +43,7 @@ int print_char(char c, int x, int y){
 
     int offset;
     if(x >= 0 && y >= 0) offset = y*VGA_WIDTH+x;
-    else offset = get_cursor();
+    else offset = vga_get_cursor();
 
     if(c == '\n'){
         y = get_offset_y(offset);
@@ -61,17 +61,17 @@ int print_char(char c, int x, int y){
 
     // TODO: Scroll
     
-    set_cursor(offset);
+    vga_set_cursor(offset);
     return offset;
 }
 
-void puts_at(char *str, int x, int y){
+void vga_print_string_at(char *str, int x, int y){
     int offset;
     if(x >= 0 && y >= 0){
         offset = y*VGA_WIDTH+x;
     }
     else{
-        offset = get_cursor();
+        offset = vga_get_cursor();
         x = get_offset_x(offset);
         y = get_offset_y(offset);
     }
@@ -105,13 +105,13 @@ void puts_at(char *str, int x, int y){
             }
         }
         else{
-            offset = print_char(*(str++), x, y);
+            offset = vga_print_char(*(str++), x, y);
             x = get_offset_x(offset);
             y = get_offset_y(offset);
         }
     }
 }
 
-void puts(char *str){
+void vga_print_string(char *str){
-    puts_at(str, -1, -1);
+    vga_print_string_at(str, -1, -1);
 }

src/kernel/drivers/vga.h

@@ -46,10 +46,10 @@
 #define VGA_PORT_CTRL 0x3D4
 #define VGA_PORT_DATA 0x3D5
 
-void set_char(int x, int y, char c);
+void vga_set_char(int x, int y, char c);
-void set_color(int x, int y, uint8_t color);
+void vga_set_color(int x, int y, uint8_t color);
-void set_cursor(int offset);
+void vga_set_cursor(int offset);
-int get_cursor();
+int vga_get_cursor();
-int print_char(char c, int x, int y);
+int vga_print_char(char c, int x, int y);
-void puts_at(char *str, int x, int y);
+void vga_print_string_at(char *str, int x, int y);
-void puts(char *str);
+void vga_print_string(char *str);

src/kernel/main.c

@@ -2,6 +2,8 @@
 #include "stdio.h"
 
 void __attribute__((cdecl)) kmain(uint64_t magic, uint64_t addr){
-    printf("Hello world!\n\x1b[32m:D\x1b[0m\n");
+    puts("\x1b[33mWARNING\x1b[0m");
+    printf(": amazing %s ahead!\n", "math");
+    printf("%i+%i=%i\n", 1, 1, 2);
     for(;;); // Halt here 
 }

src/kernel/stdio.c

@@ -1,6 +1,103 @@
+#include <stdarg.h>
+#include <stdbool.h>
 #include "stdio.h"
 #include "drivers/vga.h"
 
-void printf(char *fmt, ...){
+static char g_HexChars[] = "0123456789abcdef";
-    puts(fmt);
+
+void puts(char *str){
+    vga_print_string(str);
+}
+
+void putc(char c){
+    char str[2];
+    str[0] = c;
+    str[1] = '\0';
+    vga_print_string(str);
+}
+
+static void printf_signed(unsigned long long num, int radix){
+    char buffer[32];
+    int pos = 0;
+
+    // Convert to ASCII
+    do{
+        unsigned long long rem = num % radix;
+        num /= radix;
+        buffer[pos++] = g_HexChars[rem];
+    } while(num > 0);
+
+    while(--pos >= 0) putc(buffer[pos]); // Note reverse order
+}
+
+static void printf_unsigned(unsigned long long num, int radix){
+    if(num < 0){
+        putc('-');
+        printf_unsigned(-num, radix);
+    }
+    else printf_unsigned(num, radix);
+}
+
+void printf(char *fmt, ...){
+    // Variadic function arguments
+    va_list args;
+    va_start(args, fmt);
+
+    while(*fmt){
+        if(*fmt == '%'){
+            bool number = false;
+            bool sign = false;
+            int radix = 10;
+
+            fmt++;
+            switch(*fmt){
+                case '%':
+                    putc('%');
+                    break;
+                case 'c':
+                    putc((char)va_arg(args, int));
+                    break;
+                case 's':
+                    puts(va_arg(args, char *));
+                    break;
+                case 'd':
+                case 'i':
+                    number = true;
+                    radix = 10;
+                    sign = true;
+                    break;
+                case 'u':
+                    number = true;
+                    radix = 10;
+                    sign = false;
+                    break;
+                case 'X':
+                case 'x':
+                case 'p':
+                    number = true;
+                    radix = 16;
+                    sign = false;
+                    break;
+                case 'o':
+                    number = true;
+                    radix = 8;
+                    sign = false;
+                    break;
+                default: break;
+            }
+
+            // TODO: Implement length modifiers
+            if(number){
+                if(sign){
+                    printf_signed(va_arg(args, int), radix);
+                }
+                else{
+                    printf_unsigned(va_arg(args, unsigned int), radix);
+                }
+            }
+
+            fmt++;
+        }
+        else putc(*(fmt++));
+    }
 }

src/kernel/stdio.h

@@ -1,3 +1,5 @@
 #pragma once
 
+void puts(char *str);
+void putc(char c);
 void printf(char *fmt, ...);