Implemented Funge-98 IO procedures

src/defaultIO.nim

@@ -0,0 +1,40 @@
+import strformat
+
+## We keep the last input char to handle a pain point in the funge-98 spec :
+## when reading from the decimal input you need to read until you encounter a
+## non numeric char, but not drop it
+var defaultInputLastChar: ref int
+
+var stdIoUnbuffered = false
+
+proc defaultCharacterInput*(): int =
+  if defaultInputLastChar != nil:
+    result = defaultInputLastChar[]
+    defaultInputLastChar = nil
+    return result
+  if not stdIoUnbuffered:
+    setStdIoUnbuffered()
+    stdIoUnbuffered = true
+  return stdin.readChar().int()
+
+proc defaultDecimalInput*(): int =
+  while true: # First we need to find the next numeric char
+    let c = defaultCharacterInput()
+    if c >= int('0') and c <= int('9'):
+      result = c - int('0')
+      break
+  while true: # then we read until we encounter a non numeric char
+    let c = defaultCharacterInput()
+    if c >= int('0') and c <= int('9'):
+      result = result * 10 + c - int('0')
+    else:
+      new(defaultInputLastChar)
+      defaultInputLastChar[] = c
+      break
+  return result
+
+proc defaultCharacterOutput*(v: int) =
+  discard stdout.writeChars(@[v.char()], 0, 1)
+
+proc defaultDecimalOutput*(v: int) =
+  stdout.write(&"{v}")