455 lines
10 KiB
C++
455 lines
10 KiB
C++
#include <BAN/Debug.h>
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#include <BAN/Math.h>
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#include <ctype.h>
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#include <string.h>
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#include <sys/syscall.h>
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#include <time.h>
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#include <unistd.h>
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// sample implementation from https://pubs.opengroup.org/onlinepubs/9699919799/functions/asctime.html
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char* asctime(const struct tm* timeptr)
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{
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static constexpr char wday_name[][4] {
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"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
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};
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static constexpr char mon_name[][4] {
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"Jan", "Feb", "Mar", "Apr", "May", "Jun",
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"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
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};
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static char result[128];
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sprintf(result, "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n",
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wday_name[timeptr->tm_wday],
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mon_name[timeptr->tm_mon],
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timeptr->tm_mday, timeptr->tm_hour,
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timeptr->tm_min, timeptr->tm_sec,
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1900 + timeptr->tm_year);
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return result;
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}
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int clock_gettime(clockid_t clock_id, struct timespec* tp)
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{
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return syscall(SYS_CLOCK_GETTIME, clock_id, tp);
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}
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char* ctime(const time_t* clock)
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{
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return asctime(localtime(clock));
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}
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int nanosleep(const struct timespec* rqtp, struct timespec* rmtp)
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{
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return syscall(SYS_NANOSLEEP, rqtp, rmtp);
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}
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time_t time(time_t* tloc)
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{
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timespec tp;
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if (clock_gettime(CLOCK_REALTIME, &tp) == -1)
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return -1;
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if (tloc)
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*tloc = tp.tv_sec;
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return tp.tv_sec;
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}
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struct tm* gmtime(const time_t* timer)
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{
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static struct tm tm;
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constexpr auto is_leap_year =
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[](time_t year) -> bool
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{
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if (year % 400 == 0)
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return true;
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if (year % 100 == 0)
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return false;
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if (year % 4 == 0)
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return true;
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return false;
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};
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constexpr uint64_t month_days[] { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
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time_t time = *timer;
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tm.tm_sec = time % 60; time /= 60;
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tm.tm_min = time % 60; time /= 60;
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tm.tm_hour = time % 24; time /= 24;
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time_t total_days = time;
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tm.tm_wday = (total_days + 4) % 7;
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tm.tm_year = 1970;
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while (total_days >= 365U + is_leap_year(tm.tm_year))
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{
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total_days -= 365U + is_leap_year(tm.tm_year);
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tm.tm_year++;
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}
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bool is_leap_day = is_leap_year(tm.tm_year) && total_days == month_days[2];
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bool had_leap_day = is_leap_year(tm.tm_year) && total_days > month_days[2];
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for (tm.tm_mon = 0; tm.tm_mon < 12; tm.tm_mon++)
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if (total_days < month_days[tm.tm_mon + 1] + (is_leap_day || had_leap_day))
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break;
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tm.tm_mday = total_days - month_days[tm.tm_mon] + !had_leap_day;
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tm.tm_yday = total_days;
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tm.tm_year -= 1900;
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tm.tm_isdst = 0;
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return &tm;
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}
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struct tm* localtime(const time_t* timer)
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{
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// FIXME: support timezones
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return gmtime(timer);
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}
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size_t strftime(char* __restrict s, size_t maxsize, const char* __restrict format, const struct tm* __restrict timeptr)
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{
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size_t len = 0;
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struct conversion_t
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{
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char flag = '\0';
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int width = -1;
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char modifier = '\0';
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};
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static constexpr const char* abbr_wday[] {
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"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
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};
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static constexpr const char* full_wday[] {
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"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
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};
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static constexpr const char* abbr_mon[] {
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"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
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};
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static constexpr const char* full_mon[] {
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"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"
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};
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const auto append_string =
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[&](const char* string) -> bool
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{
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size_t string_len = strlen(string);
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if (len + string_len >= maxsize)
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return false;
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strcpy(s + len, string);
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len += string_len;
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return true;
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};
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const auto append_string_from_list =
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[&]<size_t LIST_SIZE>(int index, const char* const (&list)[LIST_SIZE]) -> bool
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{
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const char* string = "INVALID";
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if (index >= 0 && index < (int)LIST_SIZE)
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string = list[index];
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return append_string(string);
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};
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const auto append_value =
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[&](const char* format, int value) -> bool
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{
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int written = snprintf(s + len, maxsize - len, format, value);
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if (len + written >= maxsize)
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return false;
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len += written;
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return true;
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};
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while (*format && len < maxsize)
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{
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if (*format != '%')
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{
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s[len++] = *format++;
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continue;
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}
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format++;
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conversion_t conversion;
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switch (*format)
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{
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case '+':
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case '0':
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conversion.flag = *format;
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format++;
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break;
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}
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if (isdigit(*format))
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{
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conversion.width = 0;
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while (isdigit(*format))
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{
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conversion.width = (conversion.width * 10) + (*format + '0');
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format++;
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}
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}
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switch (*format)
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{
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case 'E':
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case 'O':
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dwarnln("TODO: strftime moodifiers");
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conversion.modifier = *format;
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format++;
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break;
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}
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switch (*format)
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{
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case 'a':
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if (!append_string_from_list(timeptr->tm_wday, abbr_wday))
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return 0;
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break;
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case 'A':
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if (!append_string_from_list(timeptr->tm_wday, full_wday))
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return 0;
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break;
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case 'b':
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case 'h':
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if (!append_string_from_list(timeptr->tm_mon, abbr_mon))
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return 0;
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break;
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case 'B':
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if (!append_string_from_list(timeptr->tm_mon, full_mon))
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return 0;
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break;
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case 'c':
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if (size_t ret = strftime(s + len, maxsize - len, "%a %b %e %H:%M:%S %Y", timeptr))
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len += ret;
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else return 0;
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break;
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case 'C':
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{
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if (conversion.flag == '\0')
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conversion.flag = ' ';
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if (conversion.flag == '+' && conversion.width <= 2)
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conversion.flag = '0';
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if (conversion.width < 2)
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conversion.width = 2;
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char new_format[32];
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sprintf(new_format, "%%%c%dd", conversion.flag, conversion.width);
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if (!append_value(new_format, timeptr->tm_year % 100))
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return 0;
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break;
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}
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case 'd':
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if (!append_value("%02d", timeptr->tm_mday))
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return 0;
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break;
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case 'D':
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if (size_t ret = strftime(s + len, maxsize - len, "%m/%d/%y", timeptr))
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len += ret;
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else return 0;
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break;
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case 'e':
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if (!append_value("% 2d", timeptr->tm_mday))
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return 0;
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break;
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case 'F':
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{
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if (conversion.flag == '\0')
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conversion.flag = '+';
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if (conversion.width == -1)
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conversion.width = 10;
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if (conversion.width < 6)
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conversion.width = 6;
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char new_format[32];
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sprintf(new_format, "%%%c%dY-%%m-%%d", conversion.flag, conversion.width - 6);
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if (size_t ret = strftime(s + len, maxsize - len, new_format, timeptr))
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len += ret;
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else return 0;
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break;
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}
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case 'H':
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if (!append_value("%02d", timeptr->tm_hour))
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return 0;
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break;
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case 'I':
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if (!append_value("%02d", ((timeptr->tm_hour + 11) % 12) + 1))
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return 0;
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break;
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case 'j':
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if (!append_value("%03d", timeptr->tm_yday + 1))
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return 0;
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break;
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case 'm':
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if (!append_value("%02d", timeptr->tm_mon + 1))
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return 0;
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break;
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case 'M':
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if (!append_value("%02d", timeptr->tm_min))
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return 0;
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break;
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case 'n':
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s[len++] = '\n';
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break;
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case 'p':
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if (!append_string(timeptr->tm_hour < 12 ? "AM" : "PM"))
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return 0;
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break;
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case 'r':
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if (size_t ret = strftime(s + len, maxsize - len, "%I:%M:%S %p", timeptr))
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len += ret;
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else return 0;
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break;
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case 'R':
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if (size_t ret = strftime(s + len, maxsize - len, "%H:%M", timeptr))
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len += ret;
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else return 0;
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break;
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case 'S':
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if (!append_value("%02d", timeptr->tm_sec))
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return 0;
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break;
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case 't':
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s[len++] = '\t';
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break;
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case 'T':
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if (size_t ret = strftime(s + len, maxsize - len, "%H:%M:%S", timeptr))
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len += ret;
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else return 0;
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break;
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case 'u':
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if (!append_value("%d", ((timeptr->tm_wday + 6) % 7) + 1))
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return 0;
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break;
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case 'U':
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if (!append_value("%02d", (timeptr->tm_yday - timeptr->tm_wday + 7) / 7))
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return 0;
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break;
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case 'g':
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case 'G':
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case 'V':
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{
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// Adapted from GNU libc implementation
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constexpr auto is_leap_year =
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[](int year) -> bool
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{
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if (year % 400 == 0)
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return true;
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if (year % 100 == 0)
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return false;
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if (year % 4 == 0)
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return true;
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return false;
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};
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constexpr auto iso_week_days =
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[](int yday, int wday) -> int
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{
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return yday - (wday + 382) % 7 + 3;
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};
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int year = timeptr->tm_year + 1900;
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int days = iso_week_days(timeptr->tm_yday, timeptr->tm_wday);
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if (days < 0)
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{
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year--;
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days = iso_week_days(timeptr->tm_yday + (365 + is_leap_year(year)), timeptr->tm_wday);
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}
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else
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{
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int d = iso_week_days(timeptr->tm_yday - (365 + is_leap_year(year)), timeptr->tm_wday);
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if (d >= 0)
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{
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year++;
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days = d;
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}
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}
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switch (*format)
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{
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case 'g':
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if (!append_value("%02d", ((year % 100) + 100) % 100))
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return 0;
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break;
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case 'G':
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{
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if (conversion.flag == '\0')
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conversion.flag = ' ';
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if (conversion.flag == '+' && conversion.width <= 4)
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conversion.flag = '0';
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if (conversion.width == -1)
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conversion.width = 0;
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char new_format[32];
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sprintf(new_format, "%%%c%dd", conversion.flag, conversion.width);
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if (!append_value(new_format, year))
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return 0;
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break;
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}
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case 'V':
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if (!append_value("%02d", days / 7 + 1))
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return 0;
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break;
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}
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break;
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}
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case 'w':
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if (!append_value("%d", timeptr->tm_wday))
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return 0;
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break;
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case 'W':
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if (!append_value("%02d", (timeptr->tm_yday - (timeptr->tm_wday - 1 + 7) % 7 + 7) / 7))
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return 0;
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break;
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case 'x':
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if (size_t ret = strftime(s + len, maxsize - len, "%m/%d/%y", timeptr))
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len += ret;
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else return 0;
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break;
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case 'X':
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if (size_t ret = strftime(s + len, maxsize - len, "%H:%M:%S", timeptr))
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len += ret;
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else return 0;
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break;
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case 'y':
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if (!append_value("%d", timeptr->tm_yday % 100))
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return 0;
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break;
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case 'Y':
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{
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if (conversion.flag == '\0')
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conversion.flag = ' ';
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if (conversion.flag == '+' && conversion.width <= 4)
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conversion.flag = '0';
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if (conversion.width == -1)
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conversion.width = 0;
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char new_format[32];
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sprintf(new_format, "%%%c%dd", conversion.flag, conversion.width);
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if (!append_value(new_format, 1900 + timeptr->tm_year))
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return 0;
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break;
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}
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case 'z':
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// FIXME: support timezones
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break;
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case 'Z':
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// FIXME: support timezones
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break;
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case '%':
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s[len++] = '%';
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break;
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}
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format++;
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}
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if (*format != '\0')
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return 0;
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s[len++] = '\0';
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return len;
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}
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