1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP___SUPPORT_IBM_GETTOD_ZOS_H
11#define _LIBCPP___SUPPORT_IBM_GETTOD_ZOS_H
12
13#include <time.h>
14
15inline _LIBCPP_HIDE_FROM_ABI int
16gettimeofdayMonotonic(struct timespec64* Output) {
17
18  // The POSIX gettimeofday() function is not available on z/OS. Therefore,
19  // we will call stcke and other hardware instructions in implement equivalent.
20  // Note that nanoseconds alone will overflow when reaching new epoch in 2042.
21
22  struct _t {
23    uint64_t Hi;
24    uint64_t Lo;
25  };
26  struct _t Value = {0, 0};
27  uint64_t CC = 0;
28  asm(" stcke %0\n"
29      " ipm %1\n"
30      " srlg %1,%1,28\n"
31      : "=m"(Value), "+r"(CC)::);
32
33  if (CC != 0) {
34    errno = EMVSTODNOTSET;
35    return CC;
36  }
37  uint64_t us = (Value.Hi >> 4);
38  uint64_t ns = ((Value.Hi & 0x0F) << 8) + (Value.Lo >> 56);
39  ns = (ns * 1000) >> 12;
40  us = us - 2208988800000000;
41
42  register uint64_t DivPair0 asm("r0"); // dividend (upper half), remainder
43  DivPair0 = 0;
44  register uint64_t DivPair1 asm("r1"); // dividend (lower half), quotient
45  DivPair1 = us;
46  uint64_t Divisor = 1000000;
47  asm(" dlgr %0,%2" : "+r"(DivPair0), "+r"(DivPair1) : "r"(Divisor) :);
48
49  Output->tv_sec = DivPair1;
50  Output->tv_nsec = DivPair0 * 1000 + ns;
51  return 0;
52}
53
54#endif // _LIBCPP___SUPPORT_IBM_GETTOD_ZOS_H
55