lib/sysutil/read_tsc.s

   1 #
   2 ! sections
   3
   4 .sect .text; .sect .rom; .sect .data; .sect .bss
   5
   6 .define _read_tsc       ! read the cycle counter (Pentium and up)
   7
   8 .sect .text
   9 !*===========================================================================*
  10 ! PUBLIC void read_tsc(unsigned long *high, unsigned long *low);
  11 ! Read the cycle counter of the CPU. Pentium and up.
  12 .align 16
  13 _read_tsc:
  14 .data1 0x0f             ! this is the RDTSC instruction
  15 .data1 0x31             ! it places the TSC in EDX:EAX
  16         push ebp
  17         mov ebp, 8(esp)
  18         mov (ebp), edx
  19         mov ebp, 12(esp)
  20         mov (ebp), eax
  21         pop ebp
  22         ret
  23