Ancient c library

/**
 * string.h
 */

#ifndef __STRING_H__
#define __STRING_H__

int strlen(const char *s);

int strcmp(const char *s1, const char *s2);

int strcasecmp(const char *s1, const char *s2);

int strncmp(const char *s1, const char *s2, int l);

int strncasecmp(const char *s1, const char *s2, int l);

char *strcpy(char *s1, const char *s2);

char *strncpy(char *s1, const char *s2, int l);

char *strcat(char *s1, const char *s2);

char *strncat(char *s1, const char *s2, int l);

char toupper(char c);

char tolower(char c);

char *strchr(const char *s, char c);

char *strnchr(const char *s, char c, int l);

char *strrchr(const char *s, char c);

char *strrnchr(const char *s, char c, int l);

char *strstr(const char *s1, const char *s2);

int isalnum(char c);

int isaplha(char c);

int isdigit(char c);

int islower(char c);

int isupper(char c);

int isascii(char c);

int iscntrl(char c);

int isgraph(char c);

int isprint(char c);

int ispunct(char c);

int isspace(char c);

int isxdigit(char c);

int memcmp(const void *m1, const void *m2, int l);

void *memcpy(const void *m1, const void *m2, int l);

void *memset(void *m1, int l, int v);

void swap(int *a, int *b);

#endif // __STRING_H__


/**
 * string.c
 */

#include "string.h"

#define NULL   (0)

int strlen(const char *s)
{
   int i = 0;

   while(*s++)
   {
      i++;
   }

   return i;
}

int strcmp(const char *s1, const char *s2)
{
   while(*s1 && *s2)
   {
      if (*s1 > *s2)
      {
         return 1;
      }

      if (*s1 < *s2)
      {
         return -1;
      }

      s1++;
      s2++;
   }

   if (*s1 && !*s2)
   {
      return 1;
   }

   if (!*s1 && *s2)
   {
      return -1;
   }

   return 0;
}

int strcasecmp(const char *s1, const char *s2)
{
   char c1, c2;

   while(*s1 && *s2)
   {
      c1 = toupper(*s1);
      c2 = toupper(*s2);

      if (c1 > c2)
      {
         return 1;
      }

      if (c1 < c2)
      {
         return -1;
      }

      s1++;
      s2++;
   }

   if (*s1 && !*s2)
   {
      return 1;
   }

   if (!*s1 && *s2)
   {
      return -1;
   }

   return 0;
}

int strncmp(const char *s1, const char *s2, int l)
{
   while(*s1 && *s2 && (l-- > 0))
   {
      if (*s1 > *s2)
      {
         return 1;
      }

      if (*s1 < *s2)
      {
         return -1;
      }

      s1++;
      s2++;
   }

   if (l > 0)
   {
      if (*s1 && !*s2)
      {
         return 1;
      }

      if (!*s1 && *s2)
      {
         return -1;
      }
   }

   return 0;
}

int strncasecmp(const char *s1, const char *s2, int l)
{
   char c1, c2;

   while(*s1 && *s2 && (l-- > 0))
   {
      c1 = toupper(*s1);
      c2 = toupper(*s2);

      if (c1 > c2)
      {
         return 1;
      }

      if (c1 < c2)
      {
         return -1;
      }

      s1++;
      s2++;
   }

   if (l > 0) {
      if (*s1 && !*s2)
      {
         return 1;
      }

      if (!*s1 && *s2)
      {
         return -1;
      }
   }

   return 0;
}

char *strcpy(char *s1, const char *s2)
{
   char *p = s1;

   while (*s2)
   {
      *p++ = *s2++;
   }

   *p = '\0';
   return(s1);
}

char *strncpy(char *s1, const char *s2, int l)
{
   char *p = s1;

   while (*s2 && (l-- > 0))
   {
      *p++ = *s2++;
   }

   if (l > 0)
   {
      *p = '\0';
   }

   return s1;
}

char *strcat(char *s1, const char *s2)
{
   char *p = s1;

   while (*p)
   {
      p++;
   }

   while (*s2)
   {
      *p++ = *s2++;
   }

   *p = '\0';
   return s1;
}

char *strncat(char *s1, const char *s2, int l)
{
   char *p = s1;

   while (*p)
   {
      p++;
   }

   while (*s2 && (l-- > 0))
   {
      *p++ = *s2++;
   }

   *p = '\0';
   return s1;
}

char toupper(char c)
{
   if (c >= 'a' && c <= 'z')
   {
      c -= 32;
   }

   return c;
}

char tolower(char c)
{
   if (c >= 'A' && c <= 'Z')
   {
      c += 32;
   }

   return c;
}

char *strchr(const char *s, char c)
{
   while (*s)
   {
      if (*s == c)
      {
         return (char *)s;
      }

      s++;
   }

   return NULL;
}

char *strnchr(const char *s, char c, int l)
{
   while (*s && (l-- > 0))
   {
      if (*s == c)
      {
         return (char *)s;
      }

      s++;
   }

   return NULL;
}

char *strrchr(const char *s, char c)
{
   char *p = (char *)s;
   while(*p)
   {
      p++;
   }

   while (p != s)
   {
      if (*p == c)
      {
         return (char *)p;
      }

      p--;
   }

   return NULL;
}

char *strrnchr(const char *s, char c, int l)
{
   char *p = (char *)s;
   while(*p)
   {
      p++;
   }

   while (p != s && (l-- > 0))
   {
      if (*p == c)
      {
         return (char *)p;
      }

      p--;
   }

   return NULL;
}

char *strstr(const char *s1, const char *s2)
{
   char *p = (char *)s2;
   char *r = NULL;
   int c = 0, d = 0;

   while (*p++)
   {
      c++;
   }

   p = (char *)s2;
   d = c;

   while (*s1 && (c > 0))
   {
      if (*s1 != *p)
      {
         s1++;
         p = (char *)s2;
         r = NULL;
         c = d;
      }
      else
      {
         if (!r)
         {
            r = (char *)s1;
         }

         s1++;
         p++;
         c--;
      }
   }

   if (c != 0)
   {
      r = NULL;
   }

   return r;
}

int isalnum(char c)
{
   if ((c >= '0' && c <= '9') ||
       (c >= 'A' && c <= 'Z') ||
       (c >= 'a' && c <= 'z'))
   {
      return 1;
   }

   return 0;
}

int isalpha(char c)
{
   if ((c >= 'A' && c <= 'Z') ||
       (c >= 'a' && c <= 'z'))
   {
      return 1;
   }

   return 0;
}

int isdigit(char c)
{
   if (c >= '0' && c <= '9')
   {
      return 1;
   }

   return 0;
}

int islower(char c)
{
   if (c >= 'a' && c <= 'z')
   {
      return 1;
   }

   return 0;
}

int isupper(char c)
{
   if (c >= 'A' && c <= 'Z')
   {
      return 1;
   }

   return 0;
}

int isascii(char c)
{
   if ((unsigned int)c <= 0x7F)
   {
      return 1;
   }

   return 0;
}

int iscntrl(char c)
{
   if ((c >= 0 && c <= 0x1F) || c == 0x7F)
   {
      return 1;
   }

   return 0;
}

int isgraph(char c)
{
   if ((unsigned int)c > 0x7F)
   {
      return 1;
   }

   return 0;
}

int isprint(char c)
{
   if (c >= 0x20 && c < 0x7F)
   {
      return 1;
   }

   return 0;
}

int ispunct(char c)
{
   if ((c >= ' ' && c <= '/') ||
       (c >= ':' && c <= '@') ||
       (c >= '[' && c <= '`') ||
       (c >= '{' && c <= '~'))
   {
      return 1;
   }

   return 0;
}

int isspace(char c)
{
   if (c == ' ' || c == '\t')
   {
      return 1;
   }

   return 0;
}

int isxdigit(char c)
{
   if ((c >= '0' && c <= '9') ||
       (c >= 'A' && c <= 'F') ||
       (c >= 'a' && c <= 'f'))
   {
      return 1;
   }

   return 0;
}

int memcmp(const void *m1, const void *m2, int l)
{
   const unsigned char *d;
   const unsigned char *s;

   d = (const unsigned char *)m1;
   s = (const unsigned char *)m2;

   while (l-- > 0)
   {
      if (*d > *s)
      {
         return 1;
      }

      if (*d < *s)
      {
         return -1;
      }

      d++;
      s++;
   }

   return 0;
}

void *memcpy(const void *m1, const void *m2, int l)
{
   unsigned char *d;
   const unsigned char *s;

   d = (unsigned char *)m1;
   s = (const unsigned char *)m2;

   while (l-- > 0)
   {
      *d++ = *s++;
   }

   return (void *)m1;
}

void *memset(void *m, int v, int l)
{
   unsigned char *d;

   d = (unsigned char *)m;

   while (l-- > 0)
   {
      *d++ = (unsigned char)v;
   }

   return m;
}

void swap(int *a, int *b)
{
   int t = *a;
   *a = *b;
   *b = t;
}

// End