llvm-project/compiler-rt/lib/builtins/ashrti3.c

40 lines
1.2 KiB
C

//===-- ashrti3.c - Implement __ashrti3 -----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements __ashrti3 for the compiler_rt library.
//
//===----------------------------------------------------------------------===//
#include "int_lib.h"
#ifdef CRT_HAS_128BIT
// Returns: arithmetic a >> b
// Precondition: 0 <= b < bits_in_tword
COMPILER_RT_ABI ti_int __ashrti3(ti_int a, si_int b) {
const int bits_in_dword = (int)(sizeof(di_int) * CHAR_BIT);
twords input;
twords result;
input.all = a;
if (b & bits_in_dword) /* bits_in_dword <= b < bits_in_tword */ {
// result.s.high = input.s.high < 0 ? -1 : 0
result.s.high = input.s.high >> (bits_in_dword - 1);
result.s.low = input.s.high >> (b - bits_in_dword);
} else /* 0 <= b < bits_in_dword */ {
if (b == 0)
return a;
result.s.high = input.s.high >> b;
result.s.low = (input.s.high << (bits_in_dword - b)) | (input.s.low >> b);
}
return result.all;
}
#endif // CRT_HAS_128BIT