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sfeed_time_libc.c - sfeed_tests - sfeed tests and RSS and Atom files |
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git clone git://git.codemadness.org/sfeed_tests (git://git.codemadness.org) |
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--- |
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sfeed_time_libc.c (3196B) |
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--- |
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1 /* |
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2 Test datetounix against timegm() libc implementation. |
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3 |
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4 Extract datetounix() function from sfeed.c: |
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5 |
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6 echo 'static long long' |
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7 awk '/^datetounix/ { d=1; } d && /^}$/ { exit(0); } d' < sfeed.c |
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8 echo '}' |
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9 */ |
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10 |
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11 #include <err.h> |
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12 #include <stdio.h> |
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13 #include <stdlib.h> |
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14 #include <string.h> |
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15 #include <time.h> |
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16 |
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17 static long long |
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18 datetounix(long long year, int mon, int day, int hour, int min, int sec) |
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19 { |
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20 /* seconds in a month in a regular (non-leap) year */ |
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21 static const long secs_through_month[] = { |
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22 0, 31 * 86400, 59 * 86400, 90 * 86400, |
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23 120 * 86400, 151 * 86400, 181 * 86400, 212 * 86400, |
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24 243 * 86400, 273 * 86400, 304 * 86400, 334 * 86400 }; |
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25 int is_leap = 0, cycles, centuries = 0, leaps = 0, rem; |
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26 long long t; |
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27 |
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28 /* optimization: handle common range year 1902 up to and including 2038 */ |
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29 if (year - 2ULL <= 136) { |
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30 /* amount of leap days relative to 1970: every 4 years */ |
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31 leaps = (year - 68) >> 2; |
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32 if (!((year - 68) & 3)) { |
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33 leaps--; |
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34 is_leap = 1; |
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35 } else { |
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36 is_leap = 0; |
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37 } |
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38 t = 31536000 * (year - 70) + (86400 * leaps); /* 365 * 86400 = 31536000 */ |
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39 } else { |
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40 /* general leap year calculation: |
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41 leap years occur mostly every 4 years but every 100 years |
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42 a leap year is skipped unless the year is divisible by 400 */ |
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43 cycles = (year - 100) / 400; |
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44 rem = (year - 100) % 400; |
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45 if (rem < 0) { |
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46 cycles--; |
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47 rem += 400; |
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48 } |
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49 if (!rem) { |
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50 is_leap = 1; |
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51 } else { |
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52 if (rem >= 300) { |
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53 centuries = 3; |
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54 rem -= 300; |
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55 } else if (rem >= 200) { |
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56 centuries = 2; |
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57 rem -= 200; |
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58 } else if (rem >= 100) { |
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59 centuries = 1; |
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60 rem -= 100; |
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61 } |
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62 if (rem) { |
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63 leaps = rem / 4U; |
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64 rem %= 4U; |
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65 is_leap = !rem; |
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66 } |
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67 } |
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68 leaps += (97 * cycles) + (24 * centuries) - is_leap; |
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69 |
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70 /* adjust 8 leap days from 1970 up to and including 2000: |
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71 ((30 * 365) + 8) * 86400 = 946771200 */ |
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72 t = ((year - 100) * 31536000LL) + (leaps * 86400LL) + 946771200LL; |
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73 } |
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74 t += secs_through_month[mon]; |
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75 if (is_leap && mon >= 2) |
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76 t += 86400; |
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77 t += 86400LL * (day - 1); |
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78 t += 3600LL * hour; |
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79 t += 60LL * min; |
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80 t += sec; |
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81 |
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82 return t; |
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83 } |
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84 |
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85 void |
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86 testtm(struct tm *tm) |
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87 { |
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88 time_t t1, t2; /* assume time_t is signed 64-bit */ |
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89 long long ll; |
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90 |
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91 t1 = timegm(tm); |
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92 if (t1 == (time_t)-1) { |
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93 errx(1, "timegm failed for %d, %d, %d, %d, %d, %d\n", |
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94 tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); |
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95 } |
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96 |
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97 ll = datetounix(tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); |
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98 t2 = (time_t)ll; |
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99 |
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100 if (t1 != t2) { |
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101 printf("result: %lld != %lld\n", (long long)t1, (long long)t2); |
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102 printf("for: %d, %d, %d, %d, %d, %d\n", |
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103 tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); |
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104 exit(1); |
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105 } |
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106 } |
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107 |
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108 int |
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109 main(void) |
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110 { |
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111 struct tm tm; |
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112 int y, mon, d; |
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113 long long counter = 0; |
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114 |
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115 for (y = -2069; y < 2069; y++) { |
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116 for (mon = 0; mon < 12; mon++) { |
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117 for (d = 1; d <= 31; d++) { |
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118 /* printf("DEBUG: comparing %d %d %d\n", y, mon, d);*/ |
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119 |
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120 memset(&tm, 0, sizeof(tm)); |
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121 tm.tm_year = y - 1900; |
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122 tm.tm_mon = mon - 1; |
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123 tm.tm_mday = d; |
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124 tm.tm_hour = 0; |
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125 tm.tm_min = 0; |
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126 tm.tm_sec = 0; |
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127 tm.tm_isdst = -1; |
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128 |
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129 testtm(&tm); |
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130 counter++; |
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131 } |
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132 } |
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133 } |
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134 printf("%lld dates compared, all OK\n", counter); |
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135 |
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136 return 0; |
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137 } |
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