gettimeofday.lua

local ffi = require("ffi")

ffi.cdef[[
  typedef long time_t;

  typedef struct timeval {
    time_t tv_sec;
    time_t tv_usec;
  } timeval;

  int gettimeofday(struct timeval* t, void* tzp);
]]

local gettimeofday_struct = ffi.new("timeval")
local function gettimeofday()
   ffi.C.gettimeofday(gettimeofday_struct, nil)
   return tonumber(gettimeofday_struct.tv_sec) * 1000000 +
     tonumber(gettimeofday_struct.tv_usec)
end