unable to link to gettimeofday on embedded system, elapsed time suggestions?

Question

I am trying to use gettimeofday on an embedded ARM device, however it seems as though I am unable to use it:

gnychis@ubuntu:~/Documents/coexisyst/econotag_firmware$ make
Building for board: redbee-econotag
       CC obj_redbee-econotag/econotag_coexisyst_firmware.o
LINK (romvars) econotag_coexisyst_firmware_redbee-econotag.elf
/home/gnychis/Documents/CodeSourcery/Sourcery_G++_Lite/bin/../lib/gcc/arm-none- eabi/4.3.2/../../../../arm-none-eabi/lib/libc.a(lib_a-gettimeofdayr.o): In function `_gettimeofday_r':
gettimeofdayr.c:(.text+0x1c): undefined reference to `_gettimeofday'
/home/gnychis/Documents/CodeSourcery/Sourcery_G++_Lite/bin/../lib/gcc/arm-none-eabi/4.3.2/../../../../arm-none-eabi/lib/libc.a(lib_a-sbrkr.o): In function `_sbrk_r':
sbrkr.c:(.text+0x18): undefined reference to `_sbrk'
collect2: ld returned 1 exit status
make[1]: *** [econotag_coexisyst_firmware_redbee-econotag.elf] Error 1
make: *** [mc1322x-default] Error 2

I am assuming I cannot use gettimeofday() ? Does anyone have any suggestions for being able to tell elapsed time? (e.g., 100ms)

Answer 1

What you need to do is create your own _gettimeofday() function to get it to link properly. This function could use the appropriate code to get the time for your processor, assuming you have a free-running system timer available.

#include <sys/time.h>

int _gettimeofday( struct timeval *tv, void *tzvp )
{
    uint64_t t = __your_system_time_function_here__();  // get uptime in nanoseconds
    tv->tv_sec = t / 1000000000;  // convert to seconds
    tv->tv_usec = ( t % 1000000000 ) / 1000;  // get remaining microseconds
    return 0;  // return non-zero for error
} // end _gettimeofday()