server/src/util/strings.c

/*
Copyright (c) 1998-2010, Enno Rehling <enno@eressea.de>
                         Katja Zedel <katze@felidae.kn-bremen.de
                         Christian Schlittchen <corwin@amber.kn-bremen.de>

Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
**/

#include <platform.h>

/* libc includes */
#include <string.h>

INLINE_FUNCTION unsigned int
hashstring(const char* s)
{
  unsigned int key = 0;
  while (*s) {
    key = key*37 + *s++;
  }
  return key & 0x7FFFFFFF;
}

/*
static const char *
escape_string_inplace(char * buffer, unsigned int len, unsigned int offset)
{
#define MAXQUOTES 32
  char * o;
  char * d[MAXQUOTES+1];
  int i = 0;

  o = strchr(buffer, '"');
  if (!o) {
    return buffer;
  }

  while (*o && i<MAXQUOTES) {
    char * next = strchr(o, '"');
    d[i++] = o;
    o = next?next:(o+strlen(o));
  }
  d[i] = o;
  if (i<MAXQUOTES) {
    // more than 32 hits! must go recursive
    char * start = d[i];
    unsigned int nlen = len - (start-buffer) - MAXQUOTES;
    escape_string_inplace(start, nlen, MAXQUOTES);
  }

  o[i] = '\0';
  while (--i>0) {
    const char * src = d[i];
    char * dst = d[i] + i + offset;
    size_t mlen = d[i+1] - d[i];
    memmove(dst--, src, mlen);
    *dst = '\\';
  }
  return buffer;
}
*/

INLINE_FUNCTION const char *
escape_string(const char * str, char * buffer, unsigned int len)
{
  const char * start = strchr(str, '\"');
  if (start) {
    static char s_buffer[4096]; /* STATIC_RESULT: used for return, not across calls */
    const char * p;
    char * o;
    size_t skip = start-str;

    if (buffer==NULL) {
      buffer = s_buffer;
      len = sizeof(s_buffer);
    }
    memcpy(buffer, str, skip);
    o = buffer + skip;
    p = str + skip;
    do {
      if (*p == '\"' || *p=='\\') {
        if (len<2) {
          *o = '\0';
          break;
        }
        (*o++) = '\\';
        len -= 2;
      } else {
        if (len<1) {
          *o = '\0';
          break;
        }
        --len;
      }
      (*o++) = (*p);
    } while (*p++);
    return buffer;
  }
  return str;
}

INLINE_FUNCTION unsigned int jenkins_hash(unsigned int a)
{
  a = (a+0x7ed55d16) + (a<<12);
  a = (a^0xc761c23c) ^ (a>>19);
  a = (a+0x165667b1) + (a<<5);
  a = (a+0xd3a2646c) ^ (a<<9);
  a = (a+0xfd7046c5) + (a<<3);
  a = (a^0xb55a4f09) ^ (a>>16);
  return a;
}

INLINE_FUNCTION unsigned int wang_hash(unsigned int a)
{
  a = ~a + (a << 15); // a = (a << 15) - a - 1;
  a = a ^ (a >> 12);
  a = a + (a << 2);
  a = a ^ (a >> 4);
  a = a * 2057; // a = (a + (a << 3)) + (a << 11);
  a = a ^ (a >> 16);
  return a;
}