llvm-project/compiler-rt/lib/divti3.c

35 lines
1.1 KiB
C

//===-- divti3.c - Implement __divti3 -------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements __divti3 for the compiler_rt library.
//
//===----------------------------------------------------------------------===//
#if __x86_64
#include "int_lib.h"
tu_int __udivmodti4(tu_int a, tu_int b, tu_int* rem);
// Returns: a / b
ti_int
__divti3(ti_int a, ti_int b)
{
const int bits_in_tword_m1 = (int)(sizeof(ti_int) * CHAR_BIT) - 1;
ti_int s_a = a >> bits_in_tword_m1; // s_a = a < 0 ? -1 : 0
ti_int s_b = b >> bits_in_tword_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 (__udivmodti4(a, b, (tu_int*)0) ^ s_a) - s_a; // negate if s_a == -1
}
#endif