redump.info Forum

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What:
 This is a not yet idiotproof version of findcrcs.
 It is to be used for finding a block of data which matches a specific crc.

How:
 findcrcs <file> <size of window> <crc> [more crcs...]

 File is a big file which should or may contain the searched for data.
 Size of window is the size of the block of data to find.
 Crc is the crc to find in the file (may be more then 1, but all will be matched on the window size).

 If a match is found it will print out an md5sum of the matched block for further inspection.
 For best results, add some (1MB or so) zero bytes padding around the file first.
 In a future version, this might be a selectable option of this program.

Why:
 Useful for finding audio offsets in disk images together with the redump.org database.

Warning:
 This software is not yet idiotproof!
 - It does not check arguments for validity yet (especially size of window and crc's.)
 - No paddiong option yet.
   if matching audiodata, you should pad the combined audiotracks with zero bytes at the start and end.

Compiling:
 Use "make" on any linux/unix/bsd console nearby, or if you must, an msys or cygwin environment.
 You need to use a relatively recent gcc (4.5.0+ ish I guess).
 This software uses crcutil-1.0 for providing fast crc calculations.
 crcutil is made by Andrew Kadatch and Bob Jenkins and can be found on http://code.google.com/p/crcutil/
 Do not contact them for support on findcrcs.
 The Makefile will try to pull in version 1.0 through wget if it is not supplied yet.

 Also, this program makes use of the MD5 implementation of Alexander Peslyak.
 This is found at http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5
 A small casting patch was made to support g++, this small patch is released under the same license as the original md5.c file.

Contact:
 At the moment, see the redump.org forum thread where you got this.

-V.

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~/findcrcs-0.2$ time findcrcs.exe "Moto Racer 1.bin" 46435536 9c8f607e
348061372  9c8f607e  7ca7c0881f28f2684623b3a2ae53e95b

real    0m5.743s
user    0m0.000s
sys     0m0.047s

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~/findcrcs-0.2$ time psxt001z.exe --track "Moto Racer 1.bin" 348060372 46435536 9c8f607e
psxt001z by Dremora, v0.21 beta 1

File: Moto Racer 1.bin
Start: 348060372
Size: 46435536
CRC-32: 9c8f607e

Offset correction 0 bytes, 0 samples, CRC-32 dbf4a270
Offset correction 0 bytes, 0 samples, CRC-32 dbf4a270
Offset correction 4 bytes, 1 samples, CRC-32 aaeba36a
Offset correction -4 bytes, -1 samples, CRC-32 4abb692b
...
...
Offset correction -992 bytes, -248 samples, CRC-32 a87ee8ab
Offset correction 996 bytes, 249 samples, CRC-32 3607c430
Offset correction -996 bytes, -249 samples, CRC-32 97e367cd
Offset correction 1000 bytes, 250 samples, CRC-32 9c8f607e

DONE!

Offset correction: 1000 bytes / 250 samples

real    2m27.556s
user    0m0.031s
sys     0m0.000s

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~/findcrcs-0.2$ time fff.exe -offset=348060372 -size=46435536 -crc=0x9c8f607e "
Moto Racer 1.bin"
FindFileFragment @20100709 / themabus@inbox.lv
----------------------------------------------
Input: Moto Racer 1.bin
Offset: 348060372
Size: 46435536
CRC: 9c8f607e
Shift: both
Step: 4
Range: 20000

Offset correction 0 bytes, CRC-32 dbf4a270
Offset correction 4 bytes, CRC-32 aaeba36a
Offset correction -4 bytes, CRC-32 4abb692b
Offset correction 8 bytes, CRC-32 7ed53192
...
...
Offset correction -992 bytes, CRC-32 a87ee8ab
Offset correction 996 bytes, CRC-32 3607c430
Offset correction -996 bytes, CRC-32 97e367cd
Offset correction 1000 bytes, CRC-32 9c8f607e

Fragment found!

real    0m26.102s
user    0m0.015s
sys     0m0.015s

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Usage: findcrcs [OPTION]... [--] <FILE> <WINDOWSIZE> <CRC> [MD5] [CRC [MD5]...]

Find the offset of CRCs in FILE with a window size of WINDOWSIZE.
Outputs the crc, offset and md5 of a found segment.
If an MD5 is given, it will only output or extract on a matching md5 hash.

  -e              extract the found segments with the md5 hash as filename
  -f EXTRACTFILE  use EXTRACTFILE as file to extract to
                  implies -e and -q
  -p PADDING      use PADDING amount of zero bytes around the input file
                  this can result in a negative offset in the results
                  if used with -s only an end padding will be added
  -q              quit processing after finding a match and optionally
                  extracting that match
  -s SEEDFILE     get an initial crc from SEEDFILE
                  if used with -e, the SEEDFILE will be joined with the found
                  segment