IMPLEMENTED printf()!!!!!!!

It's kinda bad :/

include/c/stdio.h

@@ -7,6 +7,14 @@
 // TODO: Make a proper file descriptor table
 #define STDOUT 1
 
+/* --- Output --- */
+void putc(char c) {
+    // write(STDOUT, &c, 1); TODO: This doesn't work and we need to use a static variable
+    static char _c;
+    _c = c;
+    write(STDOUT, &_c, 1);
+}
+
 void print(const char* s) {
     write(STDOUT, s, strlen(s));
 }
@@ -15,12 +23,53 @@ void clear() {
     print("\x1b[J");
 }
 
-void putc(char c) {
-    static char _c; // We need to pass in a static address. Idk why
-    _c = c;
-    write(STDOUT, &_c, 1);
+// TODO: Dynamically allocate memory and print once instead of calling putc for every character :/
+// TODO: Support negative numbers
+// TODO: Printing individual characters doesn't let escape sequences work :(
+int printf(const char* fmt, ...) {
+    char* argPtr = (char*)&fmt + sizeof(char*); // First arg after fmt
+    uint8_t state = 0;
+    
+    for (uint32_t i = 0; fmt[i] != '\0'; i++) {
+        char c = fmt[i];
+
+        if (state == 0) {
+             if (c == '%') state = '%';
+             else putc(c);
+        } else if (state == '%') {
+            switch (c) {
+                case 'd': // Decimal number
+                    print(itoa(*(uint32_t*)argPtr, 10));
+                    argPtr += sizeof(unsigned int);
+                    break;
+                case 'x': // Hex number
+                    print(itoa(*(uint32_t*)argPtr, 16));
+                    argPtr += sizeof(unsigned int);
+                    break;
+                case 's': // String
+                    print(*(char**)argPtr);
+                    argPtr += sizeof(char*);
+                    break;
+                case 'c': // Char
+                    putc(*(char*)argPtr);
+                    argPtr += sizeof(char);
+                    break;
+                case '%': // Just print '%'
+                    putc('%');
+                    break;
+                default:
+                    putc('%');
+                    putc(c);
+                    break;
+            }
+            state = 0;
+        }
+    }
+
+    return 0;
 }
 
+/* --- Input --- */
 char getc() {
     char* character = (char*)0x2100;
     *character = '\0';

include/c/string.h

@@ -6,19 +6,16 @@
 // Source: http://www.strudel.org.uk/itoa/
 char* itoa(uint32_t val, uint8_t base) {
     static char buf[32] = { 0 };
-
-    if (base == 0 || base > 16) {
-        // TODO: Add errors!!
-        return NULL;
-    }
+    
+    if (base == 0 || base > 16) { return NULL; }
 
     if (val == 0) {
         buf[0] = '0';
         return buf;
     }
  
-    int i = 30;
-    for (; val && i; i--, val /= base) {
+    int i;
+    for (i = 30; val && i; i--, val /= base) {
         buf[i] = "0123456789abcdef"[val % base];
     }
 

include/interrupt/exceptions.h

@@ -7,13 +7,13 @@
 // Exception handlers
 __attribute__ ((interrupt))
 void excp_divideErr(intFrame_t* iframe) { // ISR 0
-    print("\x1b[1M[ Division Error ]\n\x1b[8M");
+    printf("\x1b[1M[ Division Error ]\n\x1b[8M");
     iframe->eip++;
 }
 
 __attribute__ ((interrupt))
 void excp_doubleFault(intFrame_t* iframe, uint32_t errCode) { // ISR 8
-    print("\x1b[1M[ Double Fault ]\n\x1b[8M"); // Error code should be 0 (TODO: Maybe check if it's != 0?)
+    printf("\x1b[1M[ Double Fault ]\n\x1b[8M"); // Error code should be 0 (TODO: Maybe check if it's != 0?)
     __asm__ volatile ("cli; hlt");
 }
 
@@ -24,11 +24,7 @@ void excp_pageFault(intFrame_t* iframe, uint32_t errCode) { // ISR 14
     // cr2 should contain invalid address
     __asm__ volatile("movl %%cr2, %0" : "=r"(badAddress));
 
-    print("\x1b[1M[ Page Fault : 0x");
-    print(itoa(errCode, 16));
-    print(" ] - Tried to access 0x");
-    print(itoa(badAddress, 16));
-    print(".\n\x1b[8M");
+    printf("\x1b[1M[ Page Fault : 0x%x ] - Tried to access 0x%x.\n\x1b[8M", errCode, badAddress);
     __asm__ volatile ("cli; hlt");
 }
 

include/interrupt/syscalls.h

@@ -36,7 +36,7 @@ void sys_write() {
         int32_t result = terminalWrite(buf, len); // Call a terminal print function
         __asm__ volatile ("movl %0, %%eax" : : "r"(result));
     } else { // Not implemented
-        __asm__ volatile ("movl $1, %eax");
+        __asm__ volatile ("movl $-1, %eax");
     }
 }