ArmPkg/Library/CompilerIntrinsicsLib/Arm/lshrdi3.c

   1 /** @file
   2
   3   Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
   4
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8 /**
   9   University of Illinois/NCSA
  10   Open Source License
  11
  12   Copyright (c) 2003-2008 University of Illinois at Urbana-Champaign.
  13   All rights reserved.
  14
  15   Developed by:
  16
  17       LLVM Team
  18
  19       University of Illinois at Urbana-Champaign
  20
  21       http://llvm.org
  22
  23   Permission is hereby granted, free of charge, to any person obtaining a copy of
  24   this software and associated documentation files (the "Software"), to deal with
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  49 **/
  50
  51 #include "Llvm_int_lib.h"
  52
  53 // Returns: logical a >> b
  54
  55 // Precondition:  0 <= b < bits_in_dword
  56
  57 INT64
  58 __lshrdi3(INT64 a, INT32 b)
  59 {
  60     const int bits_in_word = (int)(sizeof(INT32) * CHAR_BIT);
  61     udwords input;
  62     udwords result;
  63     input.all = a;
  64     if (b & bits_in_word)  // bits_in_word <= b < bits_in_dword
  65     {
  66         result.high = 0;
  67         result.low = input.high >> (b - bits_in_word);
  68     }
  69     else  // 0 <= b < bits_in_word
  70     {
  71         if (b == 0)
  72             return a;
  73         result.high  = input.high >> b;
  74         result.low = (input.high << (bits_in_word - b)) | (input.low >> b);
  75     }
  76     return result.all;
  77 }