encoding/cbor: initial package implementation

core/io/io.odin

@@ -29,7 +29,7 @@ Error :: enum i32 {
 	// Invalid_Write means that a write returned an impossible count
 	Invalid_Write,
 
-	// Short_Buffer means that a read required a longer buffer than was provided
+	// Short_Buffer means that a read/write required a longer buffer than was provided
 	Short_Buffer,
 
 	// No_Progress is returned by some implementations of `io.Reader` when many calls
@@ -359,6 +359,29 @@ read_at_least :: proc(r: Reader, buf: []byte, min: int) -> (n: int, err: Error)
 	return
 }
 
+// write_full writes until the entire contents of `buf` has been written or an error occurs.
+write_full :: proc(w: Writer, buf: []byte) -> (n: int, err: Error) {
+	return write_at_least(w, buf, len(buf))
+}
+
+// write_at_least writes at least `buf[:min]` to the writer and returns the amount written.
+// If an error occurs before writing everything it is returned.
+write_at_least :: proc(w: Writer, buf: []byte, min: int) -> (n: int, err: Error) {
+	if len(buf) < min {
+		return 0, .Short_Buffer
+	}
+	for n < min && err == nil {
+		nn: int
+		nn, err = write(w, buf[n:])
+		n += nn
+	}
+
+	if err == nil && n < min {
+		err = .Short_Write
+	}
+	return
+}
+
 // copy copies from src to dst till either EOF is reached on src or an error occurs
 // It returns the number of bytes copied and the first error that occurred whilst copying, if any.
 copy :: proc(dst: Writer, src: Reader) -> (written: i64, err: Error) {