Class CachedCallStack

web/src/memory.ts:279–498

 * - reset.
 */
export class CachedCallStack implements Disposable {
  /** List of temporay arguments that can be disposed during reset. */
  tempArgs: Array<Disposable> = [];

  private memory: Memory;
  private cAllocSpace: ctypes.FTVMWasmAllocSpace;
  private cFreeSpace: ctypes.FTVMWasmFreeSpace;

  private buffer: ArrayBuffer;
  private viewU8: Uint8Array;
  private viewI32: Int32Array;
  private viewU32: Uint32Array;
  private viewF64: Float64Array;

  private stackTop: PtrOffset = 0;
  private basePtr: Pointer = 0;

  private addressToSetTargetValue: Array<[PtrOffset, PtrOffset]> = [];

  constructor(
    memory: Memory,
    allocSpace: ctypes.FTVMWasmAllocSpace,
    freeSpace: ctypes.FTVMWasmFreeSpace
  ) {
    const initCallStackSize = 128;
    this.memory = memory;
    this.cAllocSpace = allocSpace;
    this.cFreeSpace = freeSpace;
    this.buffer = new ArrayBuffer(initCallStackSize);
    this.basePtr = this.cAllocSpace(initCallStackSize);
    this.viewU8 = new Uint8Array(this.buffer);
    this.viewI32 = new Int32Array(this.buffer);
    this.viewU32 = new Uint32Array(this.buffer);
    this.viewF64 = new Float64Array(this.buffer);
    this.updateViews();
  }

  dispose(): void {
    if (this.basePtr != 0) {
      this.cFreeSpace(this.basePtr);
      this.basePtr = 0;
    }
  }
  /**
   * Rest the call stack so that it can be reused again.
   */
  reset(): void {
    this.stackTop = 0;
    assert(this.addressToSetTargetValue.length === 0);
    while (this.tempArgs.length != 0) {
      (this.tempArgs.pop() as Disposable).dispose();
    }
  }

  /**
   * Commit all the cached data to WasmMemory.
   * This function can only be called once.
   * No further store function should be called.