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Forum > Research & Development
PC98 - CTR files
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黒い灯影:
Okay, so i've been poking around in the PC98 files, now that I know more about reverse engineering.
Here are some of my notes:
--- Quote ---SGSFILE.COM - is the main SGS.DAT file loader, stays in memory, loads chunks into memory, looks like 8kb blocks (actually SGS requests 8kb blocks)
SGS.COM - main game engine
SGS.COM hands off data load requests to SGSFILE.COM to read in data from the SGS.DAT file.
The opcodes are different in the PC98 version of the SGS engine, they don't seem to match up with the WIN version.
-I only followed the flow of data through the first couple of bytes so i didn't really see how it handled the end of the file.
-I don't know if this handles the other file types the same way, i'm guessing it might. Only tested on the STARTUP.SZH file which is ID'd as 'SIL'
--- End quote ---
I found the section that processes the files after they've been read in.
Data flow decryption
I might have missed a section in the middle, when DX reached 0
--- Code: ---STARTING POINT===================
RAW DATA: Start of STARTUP.SZH [data read in started after FileIdentifier'SIL']
1400 11C4 1110 9C18 4111 8E81 8000
REG:
EAX=00002000 EBX=00000005 ECX=00002000 EDX=0000e000
ESP=00008376 EBP=60002000 ESI=0000e000 EDI=0000a000
DS=263f ES=263f SS=263f CS=263f EIP=00001477
ASM: @1477
mov dl, 7 ; DX = e007
lodsb ; READ BYTE from DS:SI into AX (RB==14h) ;AX=2014
dec bp ; decrease counter? ;BP = 2000 > 1FFF
mov dh, al ; DX = RB07 ; RB==ReadByte; ;DX = 1407
shl dh, 1 ; ;DX = 2807
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
0x14 ==> 0x28
0x00 ==>
==================
lodsb ; Reads from DS:SI into AX [Read byte: 0x00]
mov cl, 8 ; CX = 2000 > 2008 ; DX = 0007
sub cl, dl ; CX = 2008 > 2001
xor ah, ah ; AX = 2000 > 0000
shl ax, cl ; AX = 0000 > 0000
or ah, dh ; DX = 2807 ; AX = 2800
mov dh, al ; DX = 2807 > 0007
mov al, ah ; AX = 2800 > 2828
dec bp ; BP = 1FFF > 1FFE
retn
==================
stosb ; Store byte into ES:DI [AL = 0x28]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
Stored:
28
===================================
lodsb ; Reads from DS:SI into AX [Read byte: 0x11]
mov cl, 8 ; CX = 2001 > 2008 ; DX = 0006
sub cl, dl ; CX = 2001 > 2002
xor ah, ah ; AX = 2811 > 0011
shl ax, cl ; AX = 0011 > 0044 ; DX = 0006
or ah, dh ; AX = 0044 > 0044
mov dh, al ; DX = 0006 > 4406
mov al, ah ; AX = 0044 > 0000
dec bp ; BP = 1FFE > 1FFD
retn
==================
stosb ; Store byte into ES:DI [AL = 0x00]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
Stored:
2800
==================
dec dl ;DX = 4406 > 4405
shl dh, 1 ; ;DX = 4405 > 8805
retn
==================
lodsb ; Reads from DS:SI into AX [Read byte: 0xC4] ; AX = 0000 > 00C4
mov cl, 8 ; CX = 2002 > 2008 ; DX = 8805
sub cl, dl ; CX = 2002 > 2003
xor ah, ah ; AX = 00C4 > 00C4
shl ax, cl ; AX = 00C4 > 0620 ; DX = 8805
or ah, dh ; AX = 0620 > 8E20
mov dh, al ; DX = 8805 > 2005
mov al, ah ; AX = 8E20 > 8E8E
dec bp ; BP = 1FFD > 1FFC
retn
==================
stosb ; Store byte into ES:DI [AL = 0x8E]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
Stored:
2800 8E
==================
dec dl ;DX = 2005 > 2004
shl dh, 1 ; ;DX = 2004 > 4004
retn
==================
lodsb ; Reads from DS:SI into AX [Read byte: 0x11] ; AX = 8E20 > 8E11
mov cl, 8 ; CX = 2003 > 2008 ; DX = 4004
sub cl, dl ; CX = 2008 > 2004
xor ah, ah ; AX = 8E11 > 0011
shl ax, cl ; AX = 0011 > 0110 ; DX = 4004
or ah, dh ; AX = 0110 > 4110
mov dh, al ; DX = 4004 > 1004
mov al, ah ; AX = 4110 > 4141
dec bp ; BP = 1FFC > 1FFB
retn
==================
stosb ; Store byte into ES:DI [AL = 0x41]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
Stored:
2800 8E41
==================
dec dl ;DX = 1004 > 1003
shl dh, 1 ; ;DX = 1003 > 2003
retn
==================
lodsb ; Reads from DS:SI into AX [Read byte: 0x10] ; AX = 4141 > 4110
mov cl, 8 ; CX = 2004 > 2008 ; DX = 2003
sub cl, dl ; CX = 2008 > 2005
xor ah, ah ; AX = 4110 > 0010
shl ax, cl ; AX = 0010 > 0200 ; DX = 2003
or ah, dh ; AX = 0200 > 2200
mov dh, al ; DX = 2003 > 0003
mov al, ah ; AX = 2200 > 2222
dec bp ; BP = 1FFB > 1FFA
retn
==================
stosb ; Store byte into ES:DI [AL = 0x22]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
Stored:
2800 8E41 22
==================
dec dl ;DX = 0003 > 0002
shl dh, 1 ; ;DX = 0002 > 0002
retn
==================
lodsb ; Reads from DS:SI into AX [Read byte: 0x9C] ; AX = 2222 > 229C
mov cl, 8 ; CX = 2005 > 2008 ; DX = 0002
sub cl, dl ; CX = 2008 > 2006
xor ah, ah ; AX = 229C > 009C
shl ax, cl ; AX = 009C > 2700 ; DX = 0002
or ah, dh ; AX = 2700 > 2700
mov dh, al ; DX = 0002 > 0002
mov al, ah ; AX = 2700 > 2727
dec bp ; BP = 1FFA > 1FF9
retn
==================
stosb ; Store byte into ES:DI [AL = 0x27]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
Stored:
2800 8E41 2227
==================
dec dl ;DX = 0002 > 0001
shl dh, 1 ; ;DX = 0001 > 0001
retn
================== (DL > 0)
lodsb ; Reads from DS:SI into AX [Read byte: 0x18] ; AX = 2727 > 2718
mov cl, 8 ; CX = 2006 > 2008 ; DX = 0001
sub cl, dl ; CX = 2008 > 2007
xor ah, ah ; AX = 2718 > 0018
shl ax, cl ; AX = 0018 > 0C00 ; DX = 0001
or ah, dh ; AX = 0C00 > 0C00
mov dh, al ; DX = 0001 > 0001
mov al, ah ; AX = 0C00 > 0C0C
dec bp ; BP = 1FF9 > 1FF8
retn
==================
stosb ; Store byte into ES:DI [AL = 0x0C]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
Stored:
2800 8E41 2227 0C
==================
dec dl ;DX = 0001 > 0000
shl dh, 1 ; ;DX = 0000 > 0000
retn
==================
lodsb ; Reads from DS:SI into AX [Read byte: 0x41] ; AX = 0C0C > 0C41
dec bp ; BP = 1FF8 > 1FF7
retn
==================
stosb ; Store byte into ES:DI [AL = 0x41]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
Stored:
2800 8E41 2227 0C41
================= (DL == 0)
loc_11477:
mov dl, 7 ; DX = 0000 > 0007
lodsb ; Reads from DS:SI into AX [Read byte: 0x11] ; AX = 0C41>0C11
dec bp ; BP = 1FF8 > 1FF7
mov dh, al ; DX = 0007 > 1107
shl dh, 1 ; DX = 1107 > 2207
retn
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
Stored:
2800 8E41 2227 0C41
================== (DL > 0)
lodsb ; Reads from DS:SI into AX [Read byte: 0x8E] ; AX = 0C11 > 0C8E
mov cl, 8 ; CX = 2006 > 2008 ; DX = 2207
sub cl, dl ; CX = 2008 > 2001
xor ah, ah ; AX = 0C8E > 008E
shl ax, cl ; AX = 008E > 011C ; DX = 2207
or ah, dh ; AX = 011C > 231C
mov dh, al ; DX = 2207 > 1C07
mov al, ah ; AX = 231C > 2323
dec bp ; BP = 1FF8 > 1FF7
retn
==================
stosb ; Store byte into ES:DI [AL = 0x23]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
Stored:
2800 8E41 2227 0C41 23
==================
dec dl ;DX = 1C07 > 1C06
shl dh, 1 ; ;DX = 1C06 > 3806
retn
================== (DL > 0)
lodsb ; Reads from DS:SI into AX [Read byte: 0x81] ; AX = 2323 > 2381
mov cl, 8 ; CX = 2001 > 2008 ; DX = 3806
sub cl, dl ; CX = 2008 > 2002
xor ah, ah ; AX = 2381 > 0081
shl ax, cl ; AX = 0081 > 0204 ; DX = 3806
or ah, dh ; AX = 0204 > 3A04
mov dh, al ; DX = 3806 > 0406
mov al, ah ; AX = 3A04 > 3A3A
dec bp ; BP = 1FF7 > 1FF6
retn
==================
stosb ; Store byte into ES:DI [AL = 0x3A]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000
Stored:
2800 8E41 2227 0C41 233A
==================
dec dl ;DX = 0406 > 0405
shl dh, 1 ; ;DX = 0405 > 0805
retn
================== (DL > 0)
lodsb ; Reads from DS:SI into AX [Read byte: 0x80] ; AX = 3A3A > 3A80
mov cl, 8 ; CX = 2002 > 2008 ; DX = 0805
sub cl, dl ; CX = 2008 > 2003
xor ah, ah ; AX = 3A80 > 0080
shl ax, cl ; AX = 0080 > 0400 ; DX = 0805
or ah, dh ; AX = 0400 > 0C00
mov dh, al ; DX = 0805 > 0005
mov al, ah ; AX = 0C00 > 0C0C
dec bp ; BP = 1FF6 > 1FF5
retn
==================
stosb ; Store byte into ES:DI [AL = 0x0C]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000 A004 2A00 0C00 00AF 1000 1560 000A 8044 4000 2AFC 0605 5800 02A0 2530 0046 B100
Stored:
2800 8E41 2227 0C41 233A 0C
==================
dec dl ;DX = 0005 > 0004
shl dh, 1 ; ;DX = 0004 > 0004
retn
================== (DL > 0)
lodsb ; Reads from DS:SI into AX [Read byte: 0x00] ; AX = 0C0C > 0C00
mov cl, 8 ; CX = 2003 > 2008 ; DX = 0004
sub cl, dl ; CX = 2008 > 2004
xor ah, ah ; AX = 0C00 > 0000
shl ax, cl ; AX = 0000 > 0000 ; DX = 0004
or ah, dh ; AX = 0000 > 0000
mov dh, al ; DX = 0004 > 0004
mov al, ah ; AX = 0000 > 0000
dec bp ; BP = 1FF5 > 1FF4
retn
==================
stosb ; Store byte into ES:DI [AL = 0x00]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000 A004 2A00 0C00 00AF 1000 1560 000A 8044 4000 2AFC 0605 5800 02A0 2530 0046 B100
Stored:
2800 8E41 2227 0C41 233A 0C00
==================
dec dl ;DX = 0004 > 0003
shl dh, 1 ; ;DX = 0003 > 0003
retn
================== (DL > 0)
lodsb ; Reads from DS:SI into AX [Read byte: 0xA0] ; AX = 0000 > 00A0
mov cl, 8 ; CX = 2004 > 2008 ; DX = 0003
sub cl, dl ; CX = 2008 > 2005
xor ah, ah ; AX = 00A0 > 00A0
shl ax, cl ; AX = 00A0 > 0000 ; DX = 0003
or ah, dh ; AX = 00A0 > 1400
mov dh, al ; DX = 0003 > 0003
mov al, ah ; AX = 1400 > 1414
dec bp ; BP = 1FF? > 1FF1
retn
==================
stosb ; Store byte into ES:DI [AL = 0x14]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000 A004 2A00 0C00 00AF 1000 1560 000A 8044 4000 2AFC 0605 5800 02A0 2530 0046 B100
Stored:
2800 8E41 2227 0C41 233A 0C00 14
==================
dec dl ;DX = 0003 > 0002
shl dh, 1 ; ;DX = 0002 > 0002
retn
================== (DL > 0)
lodsb ; Reads from DS:SI into AX [Read byte: 0x04] ; AX = 1414 > 1404
mov cl, 8 ; CX = 2005 > 2008 ; DX = 0002
sub cl, dl ; CX = 2008 > 2006
xor ah, ah ; AX = 1404 > 0004
shl ax, cl ; AX = 0004 > 0100 ; DX = 0002
or ah, dh ; AX = 0100 > 0100
mov dh, al ; DX = 0002 > 0002
mov al, ah ; AX = 0100 > 0101
dec bp ; BP = 1FF1 > 1FF0
retn
==================
stosb ; Store byte into ES:DI [AL = 0x01]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000 A004 2A00 0C00 00AF 1000 1560 000A 8044 4000 2AFC 0605 5800 02A0 2530 0046 B100
Stored:
2800 8E41 2227 0C41 233A 0C00 1401
==================
dec dl ;DX = 0002 > 0001
shl dh, 1 ; ;DX = 0001 > 0001
retn
================== (DL > 0)
lodsb ; Reads from DS:SI into AX [Read byte: 0x2A] ; AX = 0101 > 012A
mov cl, 8 ; CX = 2006 > 2008 ; DX = 0001
sub cl, dl ; CX = 2008 > 2007
xor ah, ah ; AX = 012A > 002A
shl ax, cl ; AX = 002A > 1500 ; DX = 0001
or ah, dh ; AX = 1500 > 1500
mov dh, al ; DX = 0001 > 0001
mov al, ah ; AX = 1500 > 1515
dec bp ; BP = 1FF0 > 1FEF
==================
stosb ; Store byte into ES:DI [AL = 0x15]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000 A004 2A00 0C00 00AF 1000 1560 000A 8044 4000 2AFC 0605 5800 02A0 2530 0046 B100
Stored:
2800 8E41 2227 0C41 233A 0C00 1401 15
==================
dec dl ;DX = 0001 > 0000
shl dh, 1 ; ;DX = 0000 > 0000
retn
================
lodsb ; Reads from DS:SI into AX [Read byte: 0x00] ; AX = 1515 > 1500
dec bp ; BP = 1FEF > 1FEE
retn
==================
stosb ; Store byte into ES:DI [AL = 0x00]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000 A004 2A00 0C00 00AF 1000 1560 000A 8044 4000 2AFC 0605 5800 02A0 2530 0046 B100
Stored:
2800 8E41 2227 0C41 233A 0C00 1401 1500
================= (DL == 0)
loc_11477:
mov dl, 7 ; DX = 0000 > 0007
lodsb ; Reads from DS:SI into AX [Read byte: 0x0C] ; AX = 1500>150C
dec bp ; BP = 1FEE > 1FED
mov dh, al ; DX = 0007 > 0C07
shl dh, 1 ; DX = 0C07 > 1807
retn
================== (DL > 0)
lodsb ; Reads from DS:SI into AX [Read byte: 0x00] ; AX = 150C > 1500
mov cl, 8 ; CX = 2007 > 2008 ; DX = 1807
sub cl, dl ; CX = 2008 > 2001
xor ah, ah ; AX = 1500 > 0000
shl ax, cl ; AX = 0000 > 0000 ; DX = 1807
or ah, dh ; AX = 0000 > 1800
mov dh, al ; DX = 1807 > 0007
mov al, ah ; AX = 1800 > 1818
dec bp ; BP = 1FED > 1FEC
==================
stosb ; Store byte into ES:DI [AL = 0x18]
==================
File Data Manipulation:
VV
1400 11C4 1110 9C18 4111 8E81 8000 A004 2A00 0C00 00AF 1000 1560 000A 8044 4000 2AFC 0605 5800 02A0 2530 0046 B100
Stored:
2800 8E41 2227 0C41 233A 0C00 1401 1500
--- End code ---
JG:
Good luck with this. I took the knowledge learned about the Windows .WIN and .ANM file makeup and it didn't translate directly to the PC98 code. Its possible that SGSFILE program does a simple decryption of the data loaded, like an XOR mask. If it does have an XOR mask and we can figure it out, it might then line up to the Windows code.
黒い灯影:
Okay.. so I started working on my decryption code...
And.. it only partially works, it goes awry after a few loops, so I'm still missing something.
but I am having a bit of success, as I can see some text.. but no JP dialogue yet from the SIL files.
Also tried my program on some ANM files, and saw some patterns..
but its too early to say anything other than a few things match up.
黒い灯影:
Decryption Decompression Program complete :ojiichan
okay, so the files are actually compressed, not encrypted
The SFX files contain the name DJ TOMZAO or TOMAZO, so that's pretty neat.
I attached some of the files I ran through my program from CTR,
and also I threw in some Viper BTR files, and it also worked for those
If you wanna look through them and make any comparisons between WIN and PC98 versions of the files.
Also, the text seems to be stored in a strange format, i'll have to see how the SGS engine handles it.
JG:
You aren't using the right code page to decode the text. PC98 uses JIS X 208, which I think is Windows code page 20932.
For example "0x23 0x48" converts to wide letter H, and appears as "#H" in the text view of your hex. In other words, the "#H#A#P#P#Y#!!#E#N#D" you see is merely wide-character "HAPPY END" in JIS X.
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