text: /*
   * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
   *
   * Permission is hereby granted, free of charge, to any person obtaining 
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice shall be 
   * included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
   * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
   * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   */
  
  #ifdef ESP8266
  
  #include "inner.h"
  
  /* see inner.h */
  uint32_t
  br_i31_sub(uint32_t *a, const uint32_t *b, uint32_t ctl)
  {
  	uint32_t cc;
  	size_t u, m;
  
  	cc = 0;
  	m = (a[0] + 63) >> 5;
  	for (u = 1; u < m; u ++) {
  		uint32_t aw, bw, naw;
  
  		aw = a[u];
  		bw = b[u];
  		naw = aw - bw - cc;
  		cc = naw >> 31;
  		a[u] = MUX(ctl, naw & 0x7FFFFFFF, aw);
  	}
  	return cc;
  }
  
  #endif