llvm-project

1
//===-- ashlti3.c - Implement __ashlti3 -----------------------------------===//
2
//
3
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4
// See https://llvm.org/LICENSE.txt for license information.
5
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6
//
7
//===----------------------------------------------------------------------===//
8
//
9
// This file implements __ashlti3 for the compiler_rt library.
10
//
11
//===----------------------------------------------------------------------===//
12

13
#include "int_lib.h"
14

15
#ifdef CRT_HAS_128BIT
16

17
// Returns: a << b
18

19
// Precondition:  0 <= b < bits_in_tword
20

21
COMPILER_RT_ABI ti_int __ashlti3(ti_int a, int b) {
22
  const int bits_in_dword = (int)(sizeof(di_int) * CHAR_BIT);
23
  twords input;
24
  twords result;
25
  input.all = a;
26
  if (b & bits_in_dword) /* bits_in_dword <= b < bits_in_tword */ {
27
    result.s.low = 0;
28
    result.s.high = input.s.low << (b - bits_in_dword);
29
  } else /* 0 <= b < bits_in_dword */ {
30
    if (b == 0)
31
      return a;
32
    result.s.low = input.s.low << b;
33
    result.s.high =
34
        ((du_int)input.s.high << b) | (input.s.low >> (bits_in_dword - b));
35
  }
36
  return result.all;
37
}
38

39
#endif // CRT_HAS_128BIT
40