c - Equivalent to Arduino millis() -

i working on integration of "shunt" type sensor on electronic board. choice on linear (ltc2947), unfortunately has arduino driver. have translate in c under linux compatible microprocessor (apq8009 arm cortex-a7). have small question 1 of functions:

int16_t ltc2947_wake_up() //wake ltc2947 shutdown mode , measure wakeup time {    byte data[1];    unsigned long wakeupstart = millis(), wakeuptime;    ltc2947_wr_byte(ltc2947_reg_opctl, 0);       {       delay(1);       ltc2947_rd_byte(ltc2947_reg_opctl, data);        wakeuptime = millis() - wakeupstart;       if (data[0] == 0) //! check if in idle mode       {          return wakeuptime;       }      if (wakeuptime > 200)      {   //! failed wake due timeout, return -1         return -1;      }    }    while (true); } 

after finding usleep() equivalent delay(), can not find millis() in c. can me translate function please?

arduino millis() based on timer trips overflow interrupt @ close 1 khz, or 1 millisecond. achieve same thing, suggest setup timer on arm platform , update volatile unsigned long variable counter. equivalent of millis().

here millis() doing behind scenes:

signal(timer0_ovf_vect) {     // copy these local variables can stored in registers     // (volatile variables must read memory on every access)     unsigned long m = timer0_millis;     unsigned char f = timer0_fract;      m += millis_inc;     f += fract_inc;     if (f >= fract_max) {         f -= fract_max;         m += 1;     }      timer0_fract = f;     timer0_millis = m;     timer0_overflow_count++; }  unsigned long millis() {     unsigned long m;     uint8_t oldsreg = sreg;      // disable interrupts while read timer0_millis or might     // inconsistent value (e.g. in middle of write timer0_millis)     cli();     m = timer0_millis;     sreg = oldsreg;      return m; } 

coming embedded world, arguably first thing should when starting project on new platform establish clocks , timer interrupt going @ prescribed rate. "hello world" of embedded systems. ;) if choose @ 1 khz, you're of way there.