Routines
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18565: Decrypt Game
After the tape load, the game is still encoded. This stub sits in the loading-screen bitmap, restores the 32660 bytes below 65534 then starts the title/menu at Initialise_Game.
Decrypt_Game 18565 XOR A Use the whole screen; no rows are reserved for BASIC.
18566 LD (23659),A
18569 LD DE,65534 Point at the last encoded byte and set the length to 32660.
18572 LD HL,65533
18575 LD BC,32660
Undo the tape encoding: complement, subtract one, and store the byte one address higher. Walks backwards through the loaded game until every encoded byte is restored.
Decrypt_Game_Loop 18578 LD A,(HL) Decode one byte and step both pointers down.
18579 CPL
18580 DEC A
18581 LD (DE),A
18582 DEC DE
18583 DEC HL
18584 DEC BC
18585 LD A,B Jump to Decrypt_Game_Loop until the whole image is restored.
18586 OR C
18587 JP NZ,Decrypt_Game_Loop
18590 JP Initialise_Game Jump to Initialise_Game.
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