tandy put their sound chip on the 1A interrupt? THE TIME SERVICES?
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I started reverse engineering Where in the World is Carmen Sandiego (Enhanced DOS edition) and I'm trying to find how it generates its random seeds so I search on int 1a and the first thing I find is it's doing TANDY SOUNDS?
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Funny fact: I was trying to get an online assembler to spit out the machine code for "int 1a" but couldn't get it to, so I just went "fuck it, I can probably just do that in my head!"
Turns out I can. My brain is weird.
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Here's something I didn't know existed until just now: Where in the World is Carmen Sandiego checks your name against the list dossier list and rejects you if you use any of those names.
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PRONOUNS DETECTED: THIS GAME IS WOKE
sadly they don't have they/them on here. What about the non-binary criminals, huh?
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stretch goal: hack in at least on enby criminal with appropriate pronouns. maybe I'll just put myself in the game as one of the criminals you can apprehend
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I faked this screenshot but this is what I mean
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I think I might be able to do the hack I want by changing one byte.
I'm trying to change it so it has "daily challenges", and I think I can fix that by just switching a INT 1A from subfunction 00 to 04, making it seed the random function with the date instead of the ticks-since-midnight
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eh, I used 5 bytes. I don't need to impress anyone
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NORMAL CODE
random(*(byte )(undefined2 *)
(*(int *)(*(int *)0x39a6 * 0xe + local_c * 2 + 0x1d02) * 2 +
*(int *)(local_c * 2 + 0x24b)) - 1);
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I found another set of pronouns!
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I haven't figured out how this game stores gender, but I'm gonna go out on a limb and say it's like this:
male: 0
female: 4
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why? because they have strings like:
char* HE="He\0\0She\0"
char* HIS="His\0Hers\0";
char* HIM="Him\0Her\0";
so they can do like:
printf("Follow %s to %s lair, and capture %s alive!", badguy->name, HIS+badguy->gender, HIM+badguy->gender);
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I like how the game only asks your name, not your gender.
Player's don't have genders. Only thieves have genders.
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It's a prequel to Disco Elysium, and your gender is set to COP
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why does ghidra's "search by instruction pattern" default to BINARY?
what kind of a freak remembers the machine code for INT 21 on x86 in BINARY?
it's CD21h, not 1100110100100001!
what are you, some kind of nerd?
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I love reversing a string and it's:
void printString(char* str, int length);
and I go look what calls it, reverse that function, and it's:
void printStringSimple(char *str){
printString(str, strlen(str));
}
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it's like "aww, did someone have second thoughts about making PRINT always take a length, and got tired of having to manually calculate lengths so you just wrapped it?
and your compiler didn't inline SHIT?
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oh those poor people of Bamako! Someone stole their.
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okay so when you start a game (well, technically when you restart), the game rolls 3 dice:
0-31: where the shit was stolen from
0-2: which item it is from that location
0-8: whodunnit
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like if you roll 0 on the first, you get Athens.
For the second one, it's:
0: mask of Priam
1: Achilles's heel
2: sibyl's secret.
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The last die is used as a lookup table into the dossier's list.
It's got 1 added to it so you won't get Carmen Sandiego, as a rookie at least.
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so the game uses a pattern like this:
char * RANKS="Rookie\0Sleuth\0Private Eye\0Investigator\0Ace Detective\0"
and then latter they do:
char* your_rank = select_string(RANKS, player->rank);
and select_string is a confusing function to reverse engineer, but knowing the name I gave it gives it away: it advances through the list until it's on the nth string and returns it
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there is no check for going past the end.
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so probably it uses the same trick for pronouns. The string I'm seeing is probably like: "He\0Him\0She\0Her\0"
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Ghidra is officially sexist. It'll automatically detect the word "Female" and mark it as a string, but not the word "Male"!
Why? SEXISM!
or the fact the default minimum length for strings is 5 characters, so "female" is long enough but "male" isn't.
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correction: there IS a check for going over the end, it's just not used in every place select_string is called. so it's sometimes-safe
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they have invented a Pronoun Markup Language.
It's \x80 for He/She
It's \x81 for he/she
It's \x82 for his/her
so a string will be "\x80 mentioned \x81 liked seafood and offered me a ride in \x82 motorcycle"
and it'll fill it out based on the pronouns of the suspect
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BOOOOOOOOOOOOO
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in trying to hack myself into the game, it glitched and said I had "Hobby: Male"
no... I haven't done that in ages!
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I'm in the game now
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I modified the game's NUM_GENDERS and found where it stores the database of criminals, so now you can find me if you search SEX=NB.
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so in addition to the 5 listed attributes (and their name), the game tracks one hidden attribute:
food preference.
There are only two options:
00=Mexican
01=Seafood
what an odd binary
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@foone but they have two bits to store it?
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@aburka @foone
Every good binary needs two bits: A, B, both, neither
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@aburka 16, in fact.
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text/gemini
