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 /* Returns: a / b */ 18 19 ARM_EABI_FNALIAS(idiv, divsi3) 20 21 COMPILER_RT_ABI si_int 22 __divsi3(si_int a, si_int b) 23 { 24 const int bits_in_word_m1 = (int)(sizeof(si_int) * CHAR_BIT) - 1; 25 si_int s_a = a >> bits_in_word_m1; /* s_a = a < 0 ? -1 : 0 */ 26 si_int s_b = b >> bits_in_word_m1; /* s_b = b < 0 ? -1 : 0 */ 27 a = (a ^ s_a) - s_a; /* negate if s_a == -1 */ 28 b = (b ^ s_b) - s_b; /* negate if s_b == -1 */ 29 s_a ^= s_b; /* sign of quotient */ 30 /* 31 * On CPUs without unsigned hardware division support, 32 * this calls __udivsi3 (notice the cast to su_int). 33 * On CPUs with unsigned hardware division support, 34 * this uses the unsigned division instruction. 35 */ 36 return ((su_int)a/(su_int)b ^ s_a) - s_a; /* negate if s_a == -1 */ 37 } 38
