fleshed out binary example

examples/binary.js

@@ -8,27 +8,80 @@ let B = P.Binary;
 
 ///////////////////////////////////////////////////////////////////////
 
+// Try using another string encoding here!
+let STRING_ENCODING = "utf8";
+// let STRING_ENCODING = "ucs2";
+
+// Try rearranging these items
+let DIRECTIONS_ENUM = ["up", "down", "left", "right"];
+
 let Lang = P.createLanguage({
-  File: p => p.MagicNumber.then(p.Int32Array),
+  File: p =>
+    P.seqObj(
+      p.MagicNumber,
+      ["directions", p.Directions5],
+      ["array", p.Int32Array],
+      ["double", B.doubleLE],
+      ["string", p.String]
+    ),
+  Directions5: () =>
+    B.bitSeq([
+      6, // 6 ignored bits
+      2, // 2-bit direction #1
+      2, // 2-bit direction #2
+      2, // 2-bit direction #3
+      2, // 2-bit direction #4
+      2 // 2-bit direction #5
+    ]).map(xs => {
+      return xs.slice(1).map(x => DIRECTIONS_ENUM[x]);
+    }),
   MagicNumber: () => P.seq(B.byte(0x13), B.byte(0x37)),
   Int32: () => B.int32BE,
-  Uint32: () => B.uint32BE,
-  Int32Array: p => p.Uint32.chain(n => p.Int32.times(n))
+  UInt32: () => B.uint32BE,
+  String: p => p.UInt32.chain(n => B.encodedString(STRING_ENCODING, n)),
+  Int32Array: p => p.UInt32.chain(n => p.Int32.times(n))
 });
 
 ///////////////////////////////////////////////////////////////////////
 
 // File format:
 // - Magic number: hexadecimal "1337" byte sequence
+// - 6 ignored bits
+// - 10 bits where each pair of bits represents up/down/left/right
+//   - 0 = 0b00 = up
+//   - 1 = 0b01 = down
+//   - 2 = 0b10 = left
+//   - 3 = 0b11 = right
 // - Array length: 32-bit unsigned big-endian integer
 // - 32-bit signed integers up to the array length
+// - A double precision floating point little-endian number
+// - A 32-bit unsigned big-endian integer for the string length
+// - "string length" number of UTF-8 bytes
 // - End of file
 
 let magic = [0x13, 0x37];
 let length = [0x00, 0x00, 0x00, 0x02];
+let directions = [0b00000011, 0b00101101];
 let n512 = [0x00, 0x00, 0x02, 0x00];
 let n513 = [0x00, 0x00, 0x02, 0x01];
-let bytes = [].concat(magic, length, n512, n513);
+let d314 = Buffer.alloc(8);
+d314.writeDoubleLE(Math.PI);
+let testString = "«Piña Colada® is a beverage!»";
+let testStringByteLength = Buffer.from(testString, STRING_ENCODING).length;
+let str = Buffer.alloc(4 + testStringByteLength);
+let index = 0;
+index += str.writeUInt32BE(testStringByteLength, index);
+index += str.write(testString, index, testStringByteLength, STRING_ENCODING);
+index;
+let bytes = [
+  ...magic,
+  ...directions,
+  ...length,
+  ...n512,
+  ...n513,
+  ...d314,
+  ...str
+];
 let input = Buffer.from(bytes);
 
 function prettyPrint(x) {