llvm-project/compiler-rt/lib/divdi3.c

33 lines
1.2 KiB
C

/* ===-- divdi3.c - Implement __divdi3 -------------------------------------===
*
* The LLVM Compiler Infrastructure
*
* This file is dual licensed under the MIT and the University of Illinois Open
* Source Licenses. See LICENSE.TXT for details.
*
* ===----------------------------------------------------------------------===
*
* This file implements __divdi3 for the compiler_rt library.
*
* ===----------------------------------------------------------------------===
*/
#include "abi.h"
#include "int_lib.h"
du_int COMPILER_RT_ABI __udivmoddi4(du_int a, du_int b, du_int* rem);
/* Returns: a / b */
COMPILER_RT_ABI di_int
__divdi3(di_int a, di_int b)
{
const int bits_in_dword_m1 = (int)(sizeof(di_int) * CHAR_BIT) - 1;
di_int s_a = a >> bits_in_dword_m1; /* s_a = a < 0 ? -1 : 0 */
di_int s_b = b >> bits_in_dword_m1; /* s_b = b < 0 ? -1 : 0 */
a = (a ^ s_a) - s_a; /* negate if s_a == -1 */
b = (b ^ s_b) - s_b; /* negate if s_b == -1 */
s_a ^= s_b; /*sign of quotient */
return (__udivmoddi4(a, b, (du_int*)0) ^ s_a) - s_a; /* negate if s_a == -1 */
}