More C64 I/O routines

include/c64_basic.mfk

@@ -3,4 +3,39 @@
 import c64_kernal
 
 // print a 16-bit number on the standard output
-asm void putword(word xa) @$BDCD extern
+asm void putword(word xa) @$BDCD extern
+asm void readline() @$A560 extern
+const pointer readline_out = $200
+
+byte readword_err
+
+word readword() {
+    readline()
+    readword_err = 0
+    word result
+    word four
+    result = 0
+    byte char
+    byte i
+    i = 0
+    while true {
+        char = readline_out[i]
+        if char == 0 {
+            if i == 0 {
+                readword_err = 1
+            }
+            return result
+        }
+        if 48 <= char <= 48+9 {
+            four = result
+            four <<= 2
+            result += four
+            result <<= 1
+            result += char - 48
+        } else {
+            readword_err = 1
+            return result
+        }
+        i += 1
+    }
+}

include/stdio.mfk

@@ -7,4 +7,22 @@ void putstr(pointer str, byte len) {
         putchar(str[index])
         index += 1
     }
-}
+}
+
+void putstrz(pointer str) {
+    byte index
+    index = 0
+    while str[index] != 0 {
+        putchar(str[index])
+        index += 1
+    }
+}
+
+byte strzlen(pointer str) {
+    byte index
+    index = 0
+    while str[index] != 0 {
+        index += 1
+    }
+    return index
+}