simple logging in c

log.c

#include <math.h>
#include <stdio.h>
#include <stdarg.h>
#include <sys/types.h>
#include "log.h"

struct testss{
  u_long level;
  const char *name;
} log_names[] = {
  {LogERROR, "ERROR"},
  {LogDEBUG, "DEBUG"},
  {LogINFO, "INFO"},
  {NULL, NULL}
};

log_levels = (LogERROR|LogDEBUG|LogINFO);

extern void
log_print(int level, const char *fmt, ...)
{
  const char *log_name;
  if ((log_levels & level)!=log_levels)
    return ;

  if (level==0||level==1)
    log_name = (log_names[level+1]).name;
  else
   log_name = (log_names[(int)log2((double)level)]).name;

  va_list ap;
  va_start(ap, fmt);
  fprintf(stderr, "%s: ", log_name);
  vfprintf(stderr, fmt, ap);

  va_end(ap);
}

log.h

#ifndef _LOG_H_
#define _LOG_H_

#define LogDEBUG 0x01
#define LogINFO  0x02
#define LogERROR 0x04


int log_levels;
extern void log_print(int, const char *, ...);

#endif