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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@foone You may therefore reach secret ranks, like Modern Major General, or ŸŸŸŸŸŸŸŸ.
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