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      1 /* ===-- divsi3.c - Implement __divsi3 -------------------------------------===
      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 __divsi3 for the compiler_rt library.
     11  *
     12  * ===----------------------------------------------------------------------===
     13  */
     14 
     15 #include "int_lib.h"
     16 
     17 su_int COMPILER_RT_ABI __udivsi3(su_int n, su_int d);
     18 
     19 /* Returns: a / b */
     20 
     21 ARM_EABI_FNALIAS(idiv, divsi3)
     22 
     23 COMPILER_RT_ABI si_int
     24 __divsi3(si_int a, si_int b)
     25 {
     26     const int bits_in_word_m1 = (int)(sizeof(si_int) * CHAR_BIT) - 1;
     27     si_int s_a = a >> bits_in_word_m1;           /* s_a = a < 0 ? -1 : 0 */
     28     si_int s_b = b >> bits_in_word_m1;           /* s_b = b < 0 ? -1 : 0 */
     29     a = (a ^ s_a) - s_a;                         /* negate if s_a == -1 */
     30     b = (b ^ s_b) - s_b;                         /* negate if s_b == -1 */
     31     s_a ^= s_b;                                  /* sign of quotient */
     32     /*
     33      * On CPUs without unsigned hardware division support,
     34      *  this calls __udivsi3 (notice the cast to su_int).
     35      * On CPUs with unsigned hardware division support,
     36      *  this uses the unsigned division instruction.
     37      */
     38     return ((su_int)a/(su_int)b ^ s_a) - s_a;    /* negate if s_a == -1 */
     39 }
     40