1 /* 2 * timexsup.h - 'struct timex' support functions 3 * 4 * Written by Juergen Perlinger (perlinger@ntp.org) for the NTP project. 5 * The contents of 'html/copyright.html' apply. 6 */ 7 #ifndef TIMEXSUP_H 8 #define TIMEXSUP_H 9 10 11 /* convert a 'long' time value (in usec or nsec) into seconds, expressed 12 * as a 'double'. If 'STA_NANO' is not defined, this will always convert 13 * from usec. ('STA_NANO' is Linux specific at the time of this 14 * writing.) 15 * 16 * If 'STA_NANO' is defined, it will be checked in 'status' to decide 17 * which time base (usec or nsec) applies for this conversion. 18 */ 19 extern double dbl_from_var_long(long lval, int status); 20 21 /* convert a 'long' time value in usec into seconds, expressed as 22 * 'double'. This function is there for pure symmetry right now -- it 23 * just casts and scales without any additional bells and whistles. 24 */ 25 extern double dbl_from_usec_long(long lval); 26 27 /* If MOD_NANO is defined, set the MOD_NANO bit in '*modes' and 28 * calculate the time stamp in nsec; otherwise, calculate the result in 29 * usec. 30 * 31 * Applies proper bounds checks and saturation on LONG_MAX/LONG_MIN to 32 * avoid undefined behaviour. 33 */ 34 extern long var_long_from_dbl(double dval, unsigned int *modes); 35 36 /* convert a 'double' time value (in seconds) into usec with proper 37 * bounds check and range clamp. 38 */ 39 extern long usec_long_from_dbl(double dval); 40 41 #endif 42 /* -*- that's all folks -*- */ 43