Sega Saturn Library Formats

Edit on Github | Updated: 25th November 2020

The Sega Saturn SDK comes with pre-build static libraries such as SEGA_GFS which are required to interact with the Saturn hardware and provides a nice extraction layer .

There are two standard GNU (.a) and Hitachi (.lib). The Sega Saturn libraries contain compiled versions for both standards.

GNU Libraries

Creating IDA Signatures for GNU Saturn Libraries

The tricky part is creating signature files for IDA Pro as the standard pelf tools from IDA Pro don’t work.

You will notice for example that running pelf on LIBSGL.A will give the following output:

./pelf LIBSGL.A
LIBSGL.A: skipped 289, total 289

Running pcf on the same library provides:

LIBSGL.A: skipped 0, total 0 (SKIPPED ALL MODULES!)

What is interesting is that if you extract the .a file and run pcf on the extracting *.o files it works and create a .pat file.

My guess is that since the .o files are in COFF format PELF can’t understand them, which makes sense. So PCF should have worked right? I presume its due to COFF files normally being in a different library format (.lib) and so it doesn’t support GNU .a archives of COFF code.

So we need to write a script which extract the archive, runs pcf on all the extracting .o files and then concatinates all the .pat files into a single file.

Here is a script we wrote for exactly this purpose, note that you will need pcf and sigmake executables from the IDA Pro installation for your platform.

import os
import fnmatch
import subprocess

patfiles=[]

def execute_command(bashCommand):
    print bashCommand
    return subprocess.check_output(bashCommand.split(),stderr= subprocess.STDOUT)

def extract_library(libraryName, libraryFileName):
    execute_command("rm -rf ./"+libraryName)
    execute_command("mkdir -p "+libraryName)
    try:
        execute_command("tar -C./"+libraryName+" -xvf ./"+libraryFileName)
    except:
        pass

def loopThroughExtarctedOFiles(libraryName, filename):
    for root, dirnames, filenames in os.walk('./'+libraryName):
        for filename in fnmatch.filter(filenames, '*.[oO]'):
            print filename
            execute_command("./pcf ./"+libraryName+"/"+filename)
            patfileName = filename.replace(".o",".pat").replace(".O",".pat")
            patfiles.append("./"+libraryName+"/"+patfileName)

for root, dirnames, filenames in os.walk('.'):
    for filename in fnmatch.filter(filenames, '*.[aA]'):
        libraryName = filename.replace('.a','').replace('.A','')
        extract_library(libraryName, filename)
        loopThroughExtarctedOFiles(libraryName, filename)
        print filename
        print patfiles

execute_command("rm -f *.sig")
execute_command("./sigmake -nSegaSaturn "+'+'.join(patfiles)+" "+'SegaSaturn.sig')

Hitachi Libraries

The Sega SDK comes with pre-build Hitachi library files (*.lib) for use with the Hitachi SH2 toolchain.

Librarian (lbr)

You can obtain the Hitachi Librarian online from an old Dreamcast SDK. The Hitachi Librarian is for building and extracting static libraries, which are just a bunch of compressed object code (.obj files are assembled but not linked machine language).

You use the librarien tool (lbr.exe) from the command line like so:

lbr libraryName.lib

For example to list the object modules in SEGA_GFS.LIB on windows:

lbr.exe SEGA_GFS.LIB /LIST

Librarian Sub Command Files

Similar to Makefiles the Hitachi Librarian supports a file to tell it how to build a library from a bunch of compiled object (.obj) files.

Creating IDA Signatures for Hitachi Libraries

Currently it is unknown how to create IDA Pro Signatures from the Hitachi versions of the libraries.

But here are a few hints to see if you can help solve the problem. First lets use the librarian to extract the specific module files like so:

lbr.exe SEGA_GFS.LIB /EXTRACT=gfs /OUTPUT=gfs

The problem is the resulting extraction is also a library file format so it cannot be passed to pcf to create signatures.

Is it possible to get standard COFF object files from the hitachi libraries?


PSYQ Libraries

Note that although these library files also have the extension .lib they are not compatible with the Hitachi libraries listed above.

PSYLIB

Example to list the contents of a PsyQ static library:

PSYLIB.EXE /l LIBSN.LIB

To extract the object files:

PSYLIB.EXE /x LIBSN.LIB

Creating IDA Signatures for PSYQ Saturn Libraries

The extracted .OBJ files cannot be understood by the standard pelf or pcf but IDA Pro comes with ppsx which does support the PSYQ library file type.

The only problem is that when you run it it will complain about the saturn processor as it is only developed for the PSX MIPS based processor:

Fatal [CD.OBJ] (CD.OBJ): Unknown processor type 8