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      1 /* ===-- ashrti3.c - Implement __ashrti3 -----------------------------------===
      2  *
      3  *                     The LLVM Compiler Infrastructure
      4  *
      5  * This file is dual licensed under the MIT and the University of Illinois Open
      6  * Source Licenses. See LICENSE.TXT for details.
      7  *
      8  * ===----------------------------------------------------------------------===
      9  *
     10  * This file implements __ashrti3 for the compiler_rt library.
     11  *
     12  * ===----------------------------------------------------------------------===
     13  */
     14 
     15 #if __x86_64
     16 
     17 #include "int_lib.h"
     18 
     19 /* Returns: arithmetic a >> b */
     20 
     21 /* Precondition:  0 <= b < bits_in_tword */
     22 
     23 ti_int
     24 __ashrti3(ti_int a, si_int b)
     25 {
     26     const int bits_in_dword = (int)(sizeof(di_int) * CHAR_BIT);
     27     twords input;
     28     twords result;
     29     input.all = a;
     30     if (b & bits_in_dword)  /* bits_in_dword <= b < bits_in_tword */
     31     {
     32         /* result.s.high = input.s.high < 0 ? -1 : 0 */
     33         result.s.high = input.s.high >> (bits_in_dword - 1);
     34         result.s.low = input.s.high >> (b - bits_in_dword);
     35     }
     36     else  /* 0 <= b < bits_in_dword */
     37     {
     38         if (b == 0)
     39             return a;
     40         result.s.high  = input.s.high >> b;
     41         result.s.low = (input.s.high << (bits_in_dword - b)) | (input.s.low >> b);
     42     }
     43     return result.all;
     44 }
     45 
     46 #endif /* __x86_64 */
     47