Implementing and using ultoa (unsigned long to string)

kernel.c

@@ -58,10 +58,10 @@ void kmain (unsigned int mbootmagick, multiboot_info_t* mbootinfo) {
     if (mbootinfo->flags & MULTIBOOT_INFO_FRAMEBUFFER_INFO) {
         vga_write("\nFramebuffer: ");
         vga_write("address: 0x");
-        vga_write(ltoa(mbootinfo->framebuffer_addr, 16));
+        vga_write(ultoa(mbootinfo->framebuffer_addr, 16));
         serial_write_string("\nFramebuffer: ");
         serial_write_string("address: 0x");
-        serial_write_string(ltoa(mbootinfo->framebuffer_addr, 16));
+        serial_write_string(ultoa(mbootinfo->framebuffer_addr, 16));
         unsigned long *vmem = mbootinfo->framebuffer_addr;
         *vmem = 0xff00ff;
 

xtoa.c

@@ -49,3 +49,28 @@ char* ltoa(long value, int base) {
     }
     return result;
 }
+char* ultoa(unsigned long value, int base) {
+    char* result;
+
+    // check that the base if valid
+    if (base < 2 || base > 36) { *result = '\0'; return result; }
+
+    char* ptr = result, *ptr1 = result, tmp_char;
+    int tmp_value;
+
+    do {
+        tmp_value = value;
+        value /= base;
+        *ptr++ = "zyxwvutsrqponmlkjihgfedcba9876543210123456789abcdefghijklmnopqrstuvwxyz" [35 + (tmp_value - value * base)];
+    } while ( value );
+
+    // Apply negative sign
+    //if (tmp_value < 0) *ptr++ = '-';
+    *ptr-- = '\0';
+    while(ptr1 < ptr) {
+        tmp_char = *ptr;
+        *ptr--= *ptr1;
+        *ptr1++ = tmp_char;
+    }
+    return result;
+}

xtoa.h

@@ -3,5 +3,6 @@
 
 char* itoa(int value, int base);
 char* ltoa(long value, int base);
+char* ultoa(unsigned long value, int base);
 
 #endif