add chord serialization, vitest

src/lib/serial/chord.ts

@@ -0,0 +1,152 @@
+export interface Chord {
+  actions: number[]
+  phrase: number[]
+}
+
+/**
+ * Turns a chord into a serial-command-compatible string
+ *
+ * @example "000CC200000000000000000000000000 7468726565"
+ */
+export function chordAsCommandCompatible(chord: Chord): string {
+  return `${serializeActions(chord.actions).toString(16).padStart(32)} ${chord.phrase.map(it =>
+    it.toString(16),
+  )}`
+}
+
+/**
+ * Turns a command response into a chord
+ *
+ * @see {chordAsCommandCompatible}
+ */
+export function chordFromCommandCompatible(command: string): Chord {
+  const [actions, phrase] = command.split(" ")
+  return {
+    actions: deserializeActions(BigInt(`0x${actions}`)),
+    phrase: Array.from({length: phrase.length / 2}).map((_, i) =>
+      Number.parseInt(phrase.slice(i * 2, i * 2 + 2), 16),
+    ),
+  }
+}
+
+/**
+ * Binary serialization of actions
+ *
+ * Actions are represented as 10-bit codes, for a maximum of 12 actions
+ */
+export function serializeActions(actions: number[]): bigint {
+  let native = 0n
+  for (let i = 0; i < actions.length; i++) {
+    native |= BigInt(actions[i] & 0x3ff) << BigInt((11 - i) * 10)
+  }
+  return native
+}
+
+/**
+ * @see {serializeActions}
+ */
+export function deserializeActions(native: bigint): number[] {
+  const actions = []
+  for (let i = 0; i < 12; i++) {
+    const action = Number(native & 0x3ffn)
+    if (action !== 0) {
+      actions.push(action)
+    }
+    native >>= 10n
+  }
+
+  return actions
+}
+
+const CHL_VERSION = 1
+const CHL_MAGIC = "CHL"
+
+/**
+ * Binary serialization of the chord library
+ *
+ * Layout is as follows:
+ * ```rs
+ * struct Chords {
+ *   magic: "CHL"
+ *   version: u8
+ *   chordCount: u32
+ *   chords: chord[]
+ * }
+ *
+ * struct Chord {
+ *   id: u32
+ *   phrase: u128
+ *   actionCount: u16
+ *   actions: u8[]
+ * }
+ * ```
+ * Serialized as little endian.
+ *
+ * @param chords
+ */
+export function chordsToFile(chords: Chord[]): ArrayBuffer {
+  const actionsTotalCount = chords.reduce((size, chord) => size + chord.actions.length, 0)
+
+  const buffer = new ArrayBuffer(4 + 4 + chords.length * (4 + 16 + 2) + actionsTotalCount)
+  const view = new DataView(buffer)
+  let byteOffset = 0
+
+  for (const byte of CHL_MAGIC) {
+    view.setUint8(byteOffset++, byte.codePointAt(0)!)
+  }
+  view.setUint8(byteOffset++, CHL_VERSION)
+  view.setUint32(byteOffset, chords.length, true)
+  byteOffset += 4
+  for (const chord of chords) {
+    const actions = serializeActions(chord.actions)
+    view.setBigUint64(byteOffset, actions << 64n, true)
+    byteOffset += 8
+    view.setBigUint64(byteOffset, actions & 0xffff_ffff_ffff_ffffn, true)
+    byteOffset += 8
+
+    view.setUint16(byteOffset, chord.phrase.length, true)
+    byteOffset += 2
+    for (const action of chord.phrase) {
+      view.setUint8(byteOffset++, action)
+    }
+  }
+
+  return buffer
+}
+
+/**
+ * @see {chordsToFile}
+ */
+export function chordsFromFile(buffer: ArrayBuffer): Chord[] {
+  const view = new DataView(buffer)
+  let byteOffset = 0
+
+  let magic = ""
+  for (let i = 0; i < CHL_MAGIC.length; i++) {
+    magic += view.getUint8(byteOffset++)
+  }
+  if (magic !== CHL_MAGIC) throw new Error("Not a .chl file")
+  if (view.getUint8(byteOffset++) !== CHL_VERSION) throw Error("Invalid .chl [version]")
+
+  const chords: Chord[] = Array.from({length: view.getUint32(byteOffset, true)})
+  byteOffset += 4
+  for (let i = 0; i < chords.length; i++) {
+    let actions = view.getBigUint64(byteOffset, true) >> 64n
+    byteOffset += 8
+    actions |= view.getBigUint64(byteOffset, true)
+    byteOffset += 8
+
+    const phrase: number[] = Array.from({length: view.getUint16(byteOffset, true)})
+    byteOffset += 2
+    for (let i = 0; i < phrase.length; i++) {
+      phrase[i] = view.getUint8(byteOffset++)
+    }
+
+    chords[i] = {
+      actions: deserializeActions(actions),
+      phrase,
+    }
+  }
+
+  return chords
+}