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- /****************************************************************************
- * libs/libc/misc/lib_usub64x32.c
- *
- * Copyright (C) 2016 Gregory Nutt. All rights reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- * used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/lib/math32.h>
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: usub64x32
- *
- * Description:
- * Subtract a 32-bit value from a 64-bit value and return the 64-bit
- * difference.
- *
- * Input Parameters:
- * minuend - The number from which another number (the Subtrahend) is
- * to be subtracted.
- * subtrahend - The number that is to be subtracted.
- * difference - The location to return the difference of the two values.
- * difference may the same as one of minuend or subtrahend.
- *
- ****************************************************************************/
- void usub64x32(FAR const struct uint64_s *minuend, uint32_t subtrahend,
- FAR struct uint64_s *difference)
- {
- /* Get the MS part of the difference */
- difference->ms = minuend->ms;
- /* Check for a borrow, i.e., that is when:
- *
- * subtrahend->ls > minuend->ls
- */
- if (subtrahend > minuend->ls)
- {
- difference->ms--;
- }
- /* Get the LS part of the difference */
- difference->ls = minuend->ls - subtrahend;
- }
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