printdec.c

#include <sys/time.h>
#include <stdio.h>

#define N 10000000

char buf[N*24]; // more than enough
char *pp = buf;

__attribute__ ((noinline))
void myputchar(char ch) {
  *pp++ = ch;
}

long long current_timestamp() {
    struct timeval te;
    gettimeofday(&te, NULL); // get current time
    long long milliseconds = te.tv_sec*1000LL + te.tv_usec/1000; // caculate milliseconds
    // printf("milliseconds: %lld\n", milliseconds);
    return milliseconds;
}

///////////////////////////////////////////////////////////////////
//reference - brucehoult (small changes in order to speed it a bit)
///////////////////////////////////////////////////////////////////

void itoc_ref_1(int n) {
  unsigned u = n;
  if (n < 0) {
    //myputchar('-');
    *pp++ = '-';
    u = -n;
  }
  unsigned d = u/10, ch = u - d*10 + '0';

  if (d != 0) itoc_ref_1(d);
  //myputchar(ch);
  *pp++ = ch;

  *pp = '\0';
}

///////////////////////////////////////////////////////////////////
//ref2 - brucehoult + splitted and modified by sasa (similar noted by hamster_nz)
///////////////////////////////////////////////////////////////////

void itoc_ref_2_uint(unsigned int n) {

    unsigned int d = n/10;
    char ch = (char) (n - d*10) + '0';

    if (d != 0)
    {
     n =  d;
     itoc_ref_2_uint(n);
    }

    //putchar(ch);
    *pp++ = ch;
}

void itoc_ref_2(int n) {

  if (n < 0)
  {
     //putchar('-');
     *pp++ = '-';
     n =-n;
  }

  itoc_ref_2_uint(n);

  *pp = '\0';
}

///////////////////////////////////////////////////////////////////

void itoc_NorthGuy_1(int n) {
  unsigned u, d;
  char ch, *p, buf[12];

  u = n;
  if (n < 0) {
    //putchar('-');
    *pp++ = '-';
    u = -n;
  }

  p = buf;
  *p++ = 0;

  while(1) {
    d = u/10;
    *p++ = u - d*10 + '0';
    if (u = d) continue;
    while (ch = *--p) *pp++=ch;

    *pp = '\0';
    return;
  }
}

///////////////////////////////////////////////////////////////////

char * itoc_sasa_1(int n, char *s) {

  unsigned int u, d;

  char *p1, *p2;
  char c;

  if (n < 0)
  {
    u = -n;
    *s++ = '-';
  } else
  {
    u = n;
  }

  p1 = s;

  do {

    d = u/10;
    *s++ = (char) (u - d*10) + '0';

  } while (u = d);

  *s = '\0';

  p2 = s-1;

  while (p1 < p2)
  {
    c = *p1;
    *p1++ = *p2;
    *p2-- = c;
  }

  return s;

}

int print_dec1(unsigned n, char*s, int l)
{
    unsigned d = n/10;
    char ch = n - d*10 + '0';
    *s = ch;

    if (d == 0)
        return l;
    else
        return print_dec1(d, s + 1, l + 1);
}

void reverse(char *a, char *b)
{
    if(a < b)
    {
        char t = *b;
        *b = *a;
        *a = t;
        reverse(a+1, b-1);
    }
}

char* print_dec(int n, char *s) {
    int       len = 0;
    unsigned  u   = n;
    char     *r   = s;

    if (n < 0) {
        *(r++) = '-';
        u = -n;
        len = 1;
    }

    len += print_dec1(u, r, 0);
    *(s+len+1) = '\0';

    reverse(r, s+len);
    return s;
}

///////////////////////////////////////////////////////////////////

void process1_old ( void (*f)(int) )
{
  char *p;

  printf("\n");

  pp = buf;

  p=pp;  f(0);           printf("%s\n", p);
  p=pp;  f(123456);      printf("%s\n", p);
  p=pp;  f(-123456);     printf("%s\n", p);
  p=pp;  f( 2147483647); printf("%s\n", p);
  p=pp;  f(-2147483648); printf("%s\n", p);

}

void process1_new ( char * (*f)(int, char *) )
{
  char b[12], *p;

  printf("\n");

  p = b;

  f(0,p);           printf("%s\n", p);
  f(123456,p);      printf("%s\n", p);
  f(-123456,p);     printf("%s\n", p);
  f( 2147483647,p); printf("%s\n", p);
  f(-2147483648,p); printf("%s\n", p);
}

void process2_old ( void (*f)(int), char name[])
{
  long long ti;

  pp = buf; ti = current_timestamp();

  for (int i=-N; i<=N; ++i)
    f(i);

  ti = current_timestamp() - ti;
  printf("%s : %lld ms\n", name, ti);
}

void process2_new ( char * (*f)(int, char *), char name[])
{
  long long ti;

  pp = buf; ti = current_timestamp();

  for (int i=-N; i<=N; ++i)
    pp = f(i,pp);

  ti = current_timestamp() - ti;
  printf("%s : %lld ms\n", name, ti);
}

int main(void) {

  printf("\n"); printf("itoc_ref_1      : "); process1_old(itoc_ref_1);
  printf("\n"); printf("itoc_ref_2      : "); process1_old(itoc_ref_2);
  printf("\n"); printf("itoc_NorthGuy_1 : "); process1_old(itoc_NorthGuy_1);
  printf("\n"); printf("itoc_sasa_1     : "); process1_new(itoc_sasa_1);
  printf("\n"); printf("print_dec       : "); process1_new(print_dec);

  printf("\n");

  /* process2_old( itoc_ref_1, "Dummy test. Skip this result..." ); */
  /* printf("\n"); */

  /* ////////////////////////////////////////// */
  /* for (int i= 0; i<3; ++i) */
  /*   process2_old( itoc_ref_1, "itoc_ref_1     " ); */

  /* ////////////////////////////////////////// */
  /* for (int i= 0; i<3; ++i) */
  /*   process2_old( itoc_ref_2, "itoc_ref_2     " ); */

  /* ////////////////////////////////////////// */
  /* for (int i= 0; i<3; ++i) */
  /*   process2_old( itoc_NorthGuy_1, "itoc_NorthGuy_1" ); */

  //////////////////////////////////////////
  for (int i= 0; i<3; ++i)
    process2_new( itoc_sasa_1, "itoc_sasa_1    " );

  //////////////////////////////////////////
  for (int i= 0; i<3; ++i)
    process2_new( print_dec, "print_dec    " );


}