/* Copyright (C) 1999 Aladdin Enterprises.  All rights reserved.
  
  This file is part of GNU Ghostscript.
  
  GNU Ghostscript is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY.  No author or distributor accepts responsibility
  to anyone for the consequences of using it or for whether it serves any
  particular purpose or works at all, unless he says so in writing.  Refer
  to the GNU General Public License for full details.
  
  Everyone is granted permission to copy, modify and redistribute GNU
  Ghostscript, but only under the conditions described in the GNU General
  Public License.  A copy of this license is supposed to have been given
  to you along with GNU Ghostscript so you can know your rights and
  responsibilities.  It should be in a file named COPYING.  Among other
  things, the copyright notice and this notice must be preserved on all
  copies.
*/

/*$RCSfile: inamestr.h,v $ $Revision: 1.2.2.1 $ */
/* Name table strings definition */

#ifndef inamestr_INCLUDED
#  define inamestr_INCLUDED

#include "inameidx.h"

/*
 * In the code below, we use the hashing method described in
 * "Fast Hashing of Variable-Length Text Strings" by Peter K. Pearson,
 * pp. 677-680, CACM 33(6), June 1990.
 */

/*
 * Define a pseudo-random permutation of the integers 0..255.
 * Pearson's article claims this permutation gave good results.
 */
#define NAME_HASH_PERMUTATION_DATA\
   1, 87, 49, 12, 176, 178, 102, 166, 121, 193, 6, 84, 249, 230, 44, 163,\
   14, 197, 213, 181, 161, 85, 218, 80, 64, 239, 24, 226, 236, 142, 38, 200,\
   110, 177, 104, 103, 141, 253, 255, 50, 77, 101, 81, 18, 45, 96, 31, 222,\
   25, 107, 190, 70, 86, 237, 240, 34, 72, 242, 20, 214, 244, 227, 149, 235,\
   97, 234, 57, 22, 60, 250, 82, 175, 208, 5, 127, 199, 111, 62, 135, 248,\
   174, 169, 211, 58, 66, 154, 106, 195, 245, 171, 17, 187, 182, 179, 0, 243,\
   132, 56, 148, 75, 128, 133, 158, 100, 130, 126, 91, 13, 153, 246, 216, 219,\
   119, 68, 223, 78, 83, 88, 201, 99, 122, 11, 92, 32, 136, 114, 52, 10,\
   138, 30, 48, 183, 156, 35, 61, 26, 143, 74, 251, 94, 129, 162, 63, 152,\
   170, 7, 115, 167, 241, 206, 3, 150, 55, 59, 151, 220, 90, 53, 23, 131,\
   125, 173, 15, 238, 79, 95, 89, 16, 105, 137, 225, 224, 217, 160, 37, 123,\
   118, 73, 2, 157, 46, 116, 9, 145, 134, 228, 207, 212, 202, 215, 69, 229,\
   27, 188, 67, 124, 168, 252, 42, 4, 29, 108, 21, 247, 19, 205, 39, 203,\
   233, 40, 186, 147, 198, 192, 155, 33, 164, 191, 98, 204, 165, 180, 117, 76,\
   140, 36, 210, 172, 41, 54, 159, 8, 185, 232, 113, 196, 231, 47, 146, 120,\
   51, 65, 28, 144, 254, 221, 93, 189, 194, 139, 112, 43, 71, 109, 184, 209

/* Compute the hash for a name string.  Assume size >= 1. */
#define NAME_HASH(hash, hperm, ptr, size)\
  BEGIN\
    const byte *p = ptr;\
    uint n = size;\
\
    hash = hperm[*p++];\
    while (--n > 0)\
	hash = (hash << 8) | hperm[(byte)hash ^ *p++];\
  END

/*
 * Define the structure for a name string.  The next_index "pointer" is used
 * both for the chained hash table in the name_table and for the list of
 * free names.
 */
typedef struct name_string_s {
#if EXTEND_NAMES
#  define name_extension_bits 6
#else
#  define name_extension_bits 0
#endif
    unsigned next_index:16 + name_extension_bits; /* next name in chain or 0 */
    unsigned foreign_string:1;	/* string is allocated statically */
    unsigned mark:1;		/* GC mark bit of index for this name */
#define name_string_size_bits (14 - name_extension_bits)
#define max_name_string ((1 << name_string_size_bits) - 1)
    unsigned string_size:name_string_size_bits;
    const byte *string_bytes;
} name_string_t;
#define name_next_index(nidx, pnstr)\
   ((pnstr)->next_index)
#define set_name_next_index(nidx, pnstr, next)\
   ((pnstr)->next_index = (next))

/* Define a sub-table of name strings. */
typedef struct name_string_sub_table_s {
    name_string_t strings[NT_SUB_SIZE];
} name_string_sub_table_t;

/* Define the size of the name hash table. */
#define NT_HASH_SIZE (1024 << (EXTEND_NAMES / 2))  /* must be a power of 2 */

#endif /* inamestr_INCLUDED */
