81 lines
3.0 KiB
C
81 lines
3.0 KiB
C
/****************************************************************************
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* libc/misc/lib_uadd32x64.c
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*
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* Copyright (C) 2016 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/lib/math32.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: uadd32x64
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*
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* Description:
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* Add a 32-bit value to a 64-bit values and return the truncated 64-bit
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* sum.
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*
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* Input Parameters:
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* term1 and term2 - The values to be added
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* sum - The location to return the product of the two values. sum may
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* be one of term1 or term2
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*
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****************************************************************************/
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void uadd32x64(uint32_t term1, FAR const struct uint64_s *term2,
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FAR struct uint64_s *sum)
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{
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/* Get the MS part of the sum */
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sum->ms = term2->ms;
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/* Check for carry, i.e., that is when:
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*
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* term1 + term2->ls > UINT32_MAX
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*/
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if ((UINT32_MAX - term1) > term2->ls)
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{
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sum->ms++;
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}
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/* Get the LS part of the sum */
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sum->ls = term1 + term2->ls;
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}
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