#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>

#include <sys/time.h>

char *strncpy0(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  while (count-- && (*tmp++ = *src++) != '\0')
    /* nothing */;

  return dest;
}

char *strncpy0a(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  while (count && (*dest++ = *src++) != '\0')
    count--;

  while (count > 1)
  {
    *dest++ = 0;
    count--;
  }

  return tmp;
}

char *strncpy0b(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  while (count && (*tmp++ = *src++) != '\0')
    count--;

  while (count > 1)
  {
    *tmp++ = 0;
    count--;
  }

  return dest;
}

char *strncpy0x(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  while (count)
  {
    if (!(*tmp = *src++))
      break;
    tmp++;

    count--;
  }

  return dest;
}

char *strncpy1(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  while (count)
  {
    if ((*tmp = *src))
      src++;
    tmp++;

    count--;
  }

  return dest;
}

char *strncpy1x(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  for (; count; count--)
  {
    if ((*tmp = *src))
      src++;
    tmp++;
  }

  return dest;
}

char *strncpy2(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  while (count--)
  {
    if ((*tmp++ = *src))
      src++;
  }

  return dest;
}

char *strncpy3(char *dest, const char *src, size_t count)
{
   if (count)
   {
      char *tmp = dest;

      while (1)
      {
         *tmp = *src;
         if (*src)
           src++;
         tmp++;
         if (!count--)
           break;
      }
   }

   return dest;
}

char *strncpy4(char *dest, const char *src, size_t count)
{
   if (count)
   {
      char *tmp = dest;

      do
      {
         if ((*tmp = *src))
           ++src;
         ++tmp;
      } while (--count);
   }

   return dest;
}

char *strncpy5(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  while (count && *src)
  {
    count--;
    *tmp++ = *src++;
  }

  while (count--)
  {
    *tmp++ = 0;
  }

  return dest;
}

char *strncpy5w(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  while (count)
  {
    if (*src == '\0')
      break;

    *tmp++ = *src++;
    count--;
  }

  while (count)
  {
    *tmp++ = 0;
    count--;
  }

  return dest;
}

char *strncpy5x(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  while (count)
  {
    count--;
    if (!(*tmp++ = *src++))
      break;
  }

  while (count)
  {
    count--;
    *tmp++ = 0;
  }

  return dest;
}

char *strncpy5y(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  for (; count && *src; count--)
    *tmp++ = *src++;

  for (; count; count--)
    *tmp++ = '\0';

  return dest;
}

#define likely(x)    __builtin_expect(!!(x),1)
#define unlikely(x)  __builtin_expect(!!(x),0)

char *strncpy6(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  if (unlikely(!count))
    goto end;

loop1:
  if ((*tmp = *src++) == '\0')
    goto next;
  tmp++;
  if (likely(--count))
    goto loop1;
  else
    goto end;

loop2:
  *tmp = '\0';
next:
  tmp++;
  if (likely(--count))
    goto loop2;

end:
  return dest;
}

char *strncpy6x(char *dest, const char *src, size_t count)
{
  char *tmp = dest;

  if (unlikely(!count))
    goto end;

loop1:
  if ((*tmp = *src++) == '\0')
    goto loop2;
  tmp++;
  if (likely(--count))
    goto loop1;
  else
    goto end;

loop2:
  *tmp++ = '\0';
  if (likely(--count))
    goto loop2;

end:
  return dest;
}

void time_it(char *(*func)(char *dest, const char *src, size_t count),
             size_t size)
{
  struct timeval start;
  struct timeval end;
  long sec, usec;
  static char *string = "asdl hfaslkfh alksjfh laksjh lkajsdflkasflksdf ljhfljshf laksflaksfhlaksjhflaksfh lakshf lkds hflsd";
  static char buffer[1000];
#ifdef __CRIS__
  int count = 500000;
#else
  int count = 20000000;
#endif

  if (size > sizeof buffer)
  {
    fprintf(stderr, "Buffer too small!\n");
    exit(1);
  }

  gettimeofday(&start, NULL);

  while (count)
  {
    func(buffer, string, size);
    count--;
  }

  gettimeofday(&end, NULL);

  sec = end.tv_sec - start.tv_sec;
  if ((usec = end.tv_usec - start.tv_usec) < 0)
  {
    sec--;
    usec += 1000000;
  }

  printf("%3ld.%06ld  ", sec, usec);
  fflush(stdout);
}

void do_it(const char *name,
           char *(*func)(char *dest, const char *src, size_t count))
{
  printf("%-12s  ", name);
  fflush(stdout);
  time_it(func, 50);
  time_it(func, 100);
  time_it(func, 200);
  time_it(func, 1000);
  printf("\n");
}

#define TIME_IT(func) time_it(#func, func)

int main(int argc, char* argv[])
{
  do_it("Original", strncpy0a);
  do_it("Eric's", strncpy1);
  do_it("Timothy's", strncpy5);
  do_it("My first", strncpy5x);
  do_it("For loops", strncpy5y);
  do_it("Algorithmic", strncpy6);

  exit(0);
}