1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
|
//===-- Implementation of mktime function ---------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "src/time/mktime.h"
#include "src/__support/common.h"
#include "src/time/time_utils.h"
#include <limits.h>
namespace LIBC_NAMESPACE {
using LIBC_NAMESPACE::time_utils::TimeConstants;
static constexpr int NON_LEAP_YEAR_DAYS_IN_MONTH[] = {31, 28, 31, 30, 31, 30,
31, 31, 30, 31, 30, 31};
// Returns number of years from (1, year).
static constexpr int64_t get_num_of_leap_years_before(int64_t year) {
return (year / 4) - (year / 100) + (year / 400);
}
// Returns True if year is a leap year.
static constexpr bool is_leap_year(const int64_t year) {
return (((year) % 4) == 0 && (((year) % 100) != 0 || ((year) % 400) == 0));
}
LLVM_LIBC_FUNCTION(time_t, mktime, (struct tm * tm_out)) {
// Unlike most C Library functions, mktime doesn't just die on bad input.
// TODO(rtenneti); Handle leap seconds.
int64_t tm_year_from_base = tm_out->tm_year + TimeConstants::TIME_YEAR_BASE;
// 32-bit end-of-the-world is 03:14:07 UTC on 19 January 2038.
if (sizeof(time_t) == 4 &&
tm_year_from_base >= TimeConstants::END_OF32_BIT_EPOCH_YEAR) {
if (tm_year_from_base > TimeConstants::END_OF32_BIT_EPOCH_YEAR)
return time_utils::out_of_range();
if (tm_out->tm_mon > 0)
return time_utils::out_of_range();
if (tm_out->tm_mday > 19)
return time_utils::out_of_range();
if (tm_out->tm_hour > 3)
return time_utils::out_of_range();
if (tm_out->tm_min > 14)
return time_utils::out_of_range();
if (tm_out->tm_sec > 7)
return time_utils::out_of_range();
}
// Years are ints. A 32-bit year will fit into a 64-bit time_t.
// A 64-bit year will not.
static_assert(
sizeof(int) == 4,
"ILP64 is unimplemented. This implementation requires 32-bit integers.");
// Calculate number of months and years from tm_mon.
int64_t month = tm_out->tm_mon;
if (month < 0 || month >= TimeConstants::MONTHS_PER_YEAR - 1) {
int64_t years = month / 12;
month %= 12;
if (month < 0) {
years--;
month += 12;
}
tm_year_from_base += years;
}
bool tm_year_is_leap = is_leap_year(tm_year_from_base);
// Calculate total number of days based on the month and the day (tm_mday).
int64_t total_days = tm_out->tm_mday - 1;
for (int64_t i = 0; i < month; ++i)
total_days += NON_LEAP_YEAR_DAYS_IN_MONTH[i];
// Add one day if it is a leap year and the month is after February.
if (tm_year_is_leap && month > 1)
total_days++;
// Calculate total numbers of days based on the year.
total_days += (tm_year_from_base - TimeConstants::EPOCH_YEAR) *
TimeConstants::DAYS_PER_NON_LEAP_YEAR;
if (tm_year_from_base >= TimeConstants::EPOCH_YEAR) {
total_days += get_num_of_leap_years_before(tm_year_from_base - 1) -
get_num_of_leap_years_before(TimeConstants::EPOCH_YEAR);
} else if (tm_year_from_base >= 1) {
total_days -= get_num_of_leap_years_before(TimeConstants::EPOCH_YEAR) -
get_num_of_leap_years_before(tm_year_from_base - 1);
} else {
// Calculate number of leap years until 0th year.
total_days -= get_num_of_leap_years_before(TimeConstants::EPOCH_YEAR) -
get_num_of_leap_years_before(0);
if (tm_year_from_base <= 0) {
total_days -= 1; // Subtract 1 for 0th year.
// Calculate number of leap years until -1 year
if (tm_year_from_base < 0) {
total_days -= get_num_of_leap_years_before(-tm_year_from_base) -
get_num_of_leap_years_before(1);
}
}
}
// TODO(rtenneti): Need to handle timezone and update of tm_isdst.
int64_t seconds = tm_out->tm_sec +
tm_out->tm_min * TimeConstants::SECONDS_PER_MIN +
tm_out->tm_hour * TimeConstants::SECONDS_PER_HOUR +
total_days * TimeConstants::SECONDS_PER_DAY;
// Update the tm structure's year, month, day, etc. from seconds.
if (time_utils::update_from_seconds(seconds, tm_out) < 0)
return time_utils::out_of_range();
return static_cast<time_t>(seconds);
}
} // namespace LIBC_NAMESPACE
|
