Difference between revisions of "Graphics directory"

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Worms directories usually act as a file archive, containing (usually graphics) files. Its built-in hash table allows fast access to files by the file name.
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{{ParentArticle|[[File formats]]}}
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A Worms directory (a DIR file) acts as a file archive, containing (usually graphics) files. Its built-in hash table allows fast access to files by the file name.
  
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The DIR file format, as well as others, was first reverse-engineered by [[Skeet]], and implemented in [[Fudge Boy]]'s sprite editor.
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== File Format ==
  
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The format (as well as others) was first reverse-engineered by [[Jon Skeet]], and implemented in [[Fudge Boy]]'s [[WA directory editor|sprite editor]].
  
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File format is as follows:
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* A 12-byte header, consisting of:
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** A 4-byte signature, "DIR\x1A"
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* a 12-byte header, consisting of:
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** Complete file length, including header and table of contents (4 bytes)
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** a 4-byte signature - "DIR\x1A"
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** Address (file offset) of the directory table of contents (4 bytes)
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** complete file length, including header and table of contents (4 bytes)
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* The actual data of the files stored in the directory
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** address (file offset) of the directory table of contents (4 bytes)
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* The table of contents, consisting of:
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* the actual data of the files stored in the directory;
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** A signature (?) DWORD, 0x0000000A (4 bytes)
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* the table of contents, which consists of:
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** A 1024-entry DWORD hash table (4096 bytes). Each entry is an offset (relative to the start of the TOC) to the first file entry, whose file name matches this hash, or 0 for no matching file entries.
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** a signature (?) DWORD, 0x0000000A (4 bytes);
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** The list of files stored in the directory. Each list entry consists of:
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** a 1024-entry DWORD hash table (4096 bytes). Each entry is an offset (relative to the start of the TOC) to the first file entry, whose filename matches this hash, or 0 for no matching file entries;
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*** Offset (relative to the start of the TOC) to the next entry for this hash value, or 0 for none (4 bytes)
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** the list of files stored in the directory. Each list entry consists of:
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*** Offset within DIR file of this file entry's data (4 bytes)
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*** offset (relative to the start of the TOC) to the next entry for this hash value, of 0 for none (4 bytes)
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*** Length of file (4 bytes)
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*** offset within DIR file of this file entry's data (4 bytes)
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*** The file name, padded to a multiple of 4 characters (with at least one after trailing \0).
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*** length of file (4 bytes)
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*** the filename, padded to a multiple of 4 characters (with at least one after trailing \0).
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== Hash Calculation ==
  
 
The hash function (with which the hashes to the file names are calculated) is as follows:
 
The hash function (with which the hashes to the file names are calculated) is as follows:
  
 
  #define HASH_BITS 10
 
  #define HASH_BITS 10
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  #define HASH_SIZE (1<<HASH_BITS)
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  #define HASH_SIZE (1 << HASH_BITS)
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  static int hash (char *str)
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  static int hash(char *str)
 
  {
 
  {
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     int sum=0;
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     int sum = 0;
 
     while (*str)
 
     while (*str)
 
     {
 
     {
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         sum=((sum<<1)%HASH_SIZE)|(sum>>(HASH_BITS-1)&1);
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         sum = ((sum << 1) % HASH_SIZE) | (sum >> (HASH_BITS - 1) & 1);
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         sum+=(unsigned char)*str++;
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         sum += (unsigned char)*str++;
 
         sum %= HASH_SIZE;
 
         sum %= HASH_SIZE;
 
     }
 
     }
 
     return sum;
 
     return sum;
 
  }
 
  }

Latest revision as of 16:38, 17 April 2017

(Up to File formats)

A Worms directory (a DIR file) acts as a file archive, containing (usually graphics) files. Its built-in hash table allows fast access to files by the file name.

File Format

The format (as well as others) was first reverse-engineered by Jon Skeet, and implemented in Fudge Boy's sprite editor.

  • A 12-byte header, consisting of:
    • A 4-byte signature, "DIR\x1A"
    • Complete file length, including header and table of contents (4 bytes)
    • Address (file offset) of the directory table of contents (4 bytes)
  • The actual data of the files stored in the directory
  • The table of contents, consisting of:
    • A signature (?) DWORD, 0x0000000A (4 bytes)
    • A 1024-entry DWORD hash table (4096 bytes). Each entry is an offset (relative to the start of the TOC) to the first file entry, whose file name matches this hash, or 0 for no matching file entries.
    • The list of files stored in the directory. Each list entry consists of:
      • Offset (relative to the start of the TOC) to the next entry for this hash value, or 0 for none (4 bytes)
      • Offset within DIR file of this file entry's data (4 bytes)
      • Length of file (4 bytes)
      • The file name, padded to a multiple of 4 characters (with at least one after trailing \0).

Hash Calculation

The hash function (with which the hashes to the file names are calculated) is as follows: 

#define HASH_BITS 10
#define HASH_SIZE (1 << HASH_BITS)

static int hash(char *str)
{
    int sum = 0;
    while (*str)
    {
        sum = ((sum << 1) % HASH_SIZE) | (sum >> (HASH_BITS - 1) & 1);
        sum += (unsigned char)*str++;
        sum %= HASH_SIZE;
    }
    return sum;
}
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