Wrote partial printf implementation

src/stdio.c

@@ -1,11 +1,100 @@
 #include "stdio.h"
+#include <stddef.h>
+#include <stdbool.h>
+
+enum format_flags_t
+{
+    FORMAT_PADDING = '0',
+    FORMAT_WIDTH = '*',
+
+    FORMAT_SIGNED_DECIMAL = 'i',
+    FORMAT_UNSIGNED_DECIMAL = 'u',
+    FORMAT_UNSIGNED_OCTAL = 'o',
+    FORMAT_UNSIGNED_HEX = 'x',
+    FORMAT_STRING = 's',
+    FORMAT_COUNT = 'n',
+    FORMAT_PERCENT = '%'
+
+};
+
+char *itoa(unsigned int n, unsigned int base, unsigned int width)
+{
+    if (base < 2 || base > 16)
+    {
+        return NULL;
+    }
+    static const char *digits = "0123456789abcdef";
+    static char buffer[65];
+    char *s = &buffer[64];
+    unsigned int count = 0;
+    do
+    {
+        *--s = digits[n % base];
+        n /= base;
+        count++;
+    } while (count < width || n != 0);
+    return s;
+}
 
 int printf(const char *format, ...)
 {
-
+    va_list valist;
+    va_start(valist, format);
+    while (*format)
+    {
+        if (*format == '%')
+        {
+            size_t width = 0;
+            bool padding = false;
+            switch (*++format)
+            {
+            case FORMAT_PADDING:
+                padding = true;
+                format++;
+                break;
+            }
+            while (*format >= '0' && *format <= '9')
+            {
+                width = (width * 10) + *format - '0';
+                format++;
+            }
+            switch (*format)
+            {
+            case FORMAT_SIGNED_DECIMAL:;
+                int n = va_arg(valist, int);
+                if (n < 0)
+                {
+                    putchar('-');
+                    n *= -1;
+                }
+                puts(itoa((unsigned int)n, 10, width));
+                break;
+            case FORMAT_UNSIGNED_DECIMAL:
+                puts(itoa(va_arg(valist, unsigned int), 10, width));
+                break;
+            case FORMAT_UNSIGNED_OCTAL:
+                puts(itoa(va_arg(valist, unsigned int), 8, width));
+            case FORMAT_UNSIGNED_HEX:
+                puts(itoa(va_arg(valist, unsigned int), 16, width));
+                break;
+            case FORMAT_STRING:
+                puts(va_arg(valist, const char *));
+                break;
+            case FORMAT_PERCENT:
+                putchar('%');
+                break;
+            }
+        }
+        else
+        {
+            putchar(*format);
+        }
+        format++;
+    }
+    va_end(valist);
+    return 0;
 }
 
 int sprintf(char *str, const char *format, ...)
 {
-    
 }