Time/CPU Cycles
Intel/AMD have an inst that returns the num of CPU cycles since boot.  This is 
not a steady, calibrated real time value.  TempleOS measures it and you can 
convert with cnts.time_stamp_freq, a value continuously calibrated from other 
cnts.
Busy                Funct Loosely timed.
CPURep              Funct Report number of cores and clock freq.
GetTSC              Funct _extern SYS_INITRAMFS_PTR U8* sys_initramfs_ptr;
PortNop             Funct Innoculous (reads IRQ Mask) which should take fixed time
cnts                GlbVar CCntsGlbls cnts= {1,0,2676302000,2676302,2676302000,FALSE};


                                   
Time/Date
Dates are 32-bit signed ints representing the number of days since the birth of 
Christ.  Negative values represent B.C.E. dates.

DayOfWeek           Funct Day of week, given 32-bit day since AD 0.
FirstDayOfMon       Funct First day of month, given 32-bit day since AD 0.
FirstDayOfYear      Funct First day of year, given 32-bit day since AD 0.
LastDayOfMon        Funct Last day of month, given 32-bit day since AD 0.
LastDayOfYear       Funct Last day of year, given 32-bit day since AD 0.
YearStartDate       Funct 32-bit day since AD 0, given year number.
mon_start_days1     GlbVar U16 mon_start_days1[12]=
mon_start_days2     GlbVar U16 mon_start_days2[12]=


                                
Time/Date/CDate
TempleOS uses a 64-bit value, CDate, for date/time.  The upper 32-bits are the 
days since Christ.  The lower 32-bits store time of day divided by 4 billion 
which works out to 49710ths of a second.  You can subtract two CDate's to get a 
time span.

Use CDATE_FREQ to convert.

Date2Struct         Funct Cvt CDate to CDateStruct.
Now                 Funct Current datetime.
Str2Date            Funct {
Struct2Date         Funct Cvt CDateStruct to CDate.
local_time_offset   GlbVar CDate local_time_offset;


                                  
Time/Jiffies
One jiffy is one time slice.  cnts.jiffies returns time slices since boot.

SysTimerRead reads the timer ticks since boot.  It's not as fast as GetTSC.

Use JIFFY_FREQ to convert cnts.jiffies.

Use SYS_TIMER_FREQ to convert SysTimerRead.

Sleep               Funct Not for power-saving. It is to make a program pause without hogging the CPU.
SleepUntil          Funct Not for power-saving. It is to make a program pause without hogging the CPU.
SysTimerRead        Funct System timer count with overflow already handled.
cnts                GlbVar CCntsGlbls cnts= {1,0,2676302000,2676302,2676302000,FALSE};


                                  
Time/Seconds
Beat                Funct Time in music beats.
Blink               Funct Return TRUE, then FALSE, then TRUE at given frequency.
tM                  Funct Time in seconds synced to music subsystem.
tS                  Funct Time since boot in seconds as a float.