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 
15 static inline int gettimeofdayMonotonic(struct timespec64* Output) {
16 
17   // The POSIX gettimeofday() function is not available on z/OS. Therefore,
18   // we will call stcke and other hardware instructions in implement equivalent.
19   // Note that nanoseconds alone will overflow when reaching new epoch in 2042.
20 
21   struct _t {
22     uint64_t Hi;
23     uint64_t Lo;
24   };
25   struct _t Value = {0, 0};
26   uint64_t CC = 0;
27   asm(" stcke %0\n"
28       " ipm %1\n"
29       " srlg %1,%1,28\n"
30       : "=m"(Value), "+r"(CC)::);
31 
32   if (CC != 0) {
33     errno = EMVSTODNOTSET;
34     return CC;
35   }
36   uint64_t us = (Value.Hi >> 4);
37   uint64_t ns = ((Value.Hi & 0x0F) << 8) + (Value.Lo >> 56);
38   ns = (ns * 1000) >> 12;
39   us = us - 2208988800000000;
40 
41   register uint64_t DivPair0 asm("r0"); // dividend (upper half), remainder
42   DivPair0 = 0;
43   register uint64_t DivPair1 asm("r1"); // dividend (lower half), quotient
44   DivPair1 = us;
45   uint64_t Divisor = 1000000;
46   asm(" dlgr %0,%2" : "+r"(DivPair0), "+r"(DivPair1) : "r"(Divisor) :);
47 
48   Output->tv_sec = DivPair1;
49   Output->tv_nsec = DivPair0 * 1000 + ns;
50   return 0;
51 }
52 
53 #endif // _LIBCPP_SUPPORT_IBM_GETTOD_ZOS_H
54