implemented binary encoding for all basic structs

2017-07-13 17:42:21 +02:00
parent 6c8876d282
commit 252bec0ad2
6 changed files with 1056 additions and 21 deletions
--- a/src/Encoding.js
+++ b/src/Encoding.js
@@ -0,0 +1,102 @@
+import utf8 from 'utf-8'
+
+const bits7 = 0b1111111
+
+export class BinaryLength {
+  constructor () {
+    this.length = 0
+  }
+  writeUint8 (num) {
+    this.length++
+  }
+  writeVarUint (num) {
+    while (num >= 0b10000000) {
+      this.length++
+      num >>= 7
+    }
+    this.length++
+  }
+  writeVarString (str) {
+    let len = utf8.setBytesFromString(str).length
+    this.writeVarUint(len)
+    this.length += len
+  }
+  writeOpID (id) {
+    this.writeVarUint(id[0])
+    this.writeVarUint(id[1])
+  }
+}
+
+export class BinaryEncoder {
+  constructor (binaryLength) {
+    this.dataview = new DataView(new ArrayBuffer(binaryLength.length))
+    this.pos = 0
+  }
+  writeUint8 (num) {
+    this.dataview.setUint8(this.pos++, num)
+  }
+  writeVarUint (num) {
+    while (num >= 0b10000000) {
+      this.dataview.setUint8(this.pos++, 0b10000000 | (bits7 & num))
+      num >>= 7
+    }
+    this.dataview.setUint8(this.pos++, bits7 & num)
+  }
+  writeVarString (str) {
+    let bytes = utf8.setBytesFromString(str)
+    let len = bytes.length
+    this.writeVarUint(len)
+    for (let i = 0; i < len; i++) {
+      this.dataview.setUint8(this.pos++, bytes[i])
+    }
+  }
+  writeOpID (id) {
+    this.writeVarUint(id[0])
+    this.writeVarUint(id[1])
+  }
+}
+
+export class BinaryDecoder {
+  constructor (dataview) {
+    this.dataview = dataview
+    this.pos = 0
+  }
+  skip8 () {
+    this.pos++
+  }
+  skip16 () {
+    this.pos += 2
+  }
+  skip32 () {
+    this.pos += 4
+  }
+  skipVar () {
+    while (this.dataview.getUint8(this.pos++) >= 1 << 7) { }
+  }
+  readUint8 () {
+    return this.dataview.getUint8(this.pos++)
+  }
+  readVarUint () {
+    let num = 0
+    let len = 0
+    while (true) {
+      let r = this.dataview.getUint8(this.pos++)
+      num = num | ((r & bits7) << len)
+      len += 7
+      if (r < 1 << 7) {
+        return num
+      }
+    }
+  }
+  readVarString () {
+    let len = this.readVarUint()
+    let bytes = new Array(len)
+    for (let i = 0; i < len; i++) {
+      bytes[i] = this.dataview.getUint8(this.pos++)
+    }
+    return utf8.getStringFromBytes(bytes)
+  }
+  readOpID () {
+    return [this.readVarUint(), this.readVarUint()]
+  }
+}