define: DUK_OPT_HEAPPTR_ENC16
introduced: 1.1.0
requires:
  - DUK_OPT_HEAPPTR16
tags:
  - lowmemory
  - experimental
description: >
  Use together with DUK_OPT_HEAPPTR16 for heap pointer compression.
  DUK_OPT_HEAPPTR_ENC16(udata,p) is a macro with a userdata and void ptr
  argument, and a duk_uint16_t return value.  The userdata argument is the
  heap userdata value given at heap creation.