Routines
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24028: Compare blackboard contents with combinations
Used by the routine at 24175. Compares the bike and storeroom combinations with what ERIC has just written on a blackboard. Unchains the bike or gives ERIC the storeroom key if there is a match.
Input
H 127
24028 LD D,H D=127
24029 LD L,251 Reset all of ERIC's status flags at 32763 now that he's no longer writing on the board
24031 LD (HL),0
24033 LD L,156 HL=32668 (combinations)
24035 LD BC,2052 B=8 (4 numbers, 4 letters), C=4
24038 RES 7,(HL) Reset bit 7 of each combination number/letter; bit 7 will be set later if there is a match with what ERIC wrote on the board
24040 INC L
24041 DJNZ 24038
24043 LD L,216 HL=32728 (which holds the identifier of the blackboard ERIC wrote on)
24045 LD L,(HL) Point HL at byte 1 of the relevant blackboard buffer (bytes 2-5 hold the first 4 characters ERIC wrote)
24046 INC L
24047 LD B,C B=4
24048 INC L Return unless at least four letters were written on the board by ERIC
24049 BIT 7,(HL)
24051 RET NZ
24052 DJNZ 24048
24054 EX DE,HL Point DE at the last byte of the blackboard buffer
24055 LD L,156 HL=32668 (combinations)
24057 LD B,8 4 numbers, 4 letters
24059 LD A,(DE) A=ASCII code of the character written on the board
24060 CP 96 Is it upper case?
24062 JR C,24066 Jump if so
24064 SUB 32 Make lower case characters upper case
24066 CP (HL) Does the character written on the board match the combination number/letter?
24067 JR Z,24073 Jump if so
24069 INC L Point to the next combination number/letter
24070 DJNZ 24066
24072 RET
24073 DEC E Point to the next character written on the board
24074 SET 7,(HL) Signal: matching character
24076 DEC C Next combination letter/number
24077 JR NZ,24055 Jump back to check the remaining numbers/letters
24079 LD L,156 HL=32668 (combinations)
24081 LD B,4 There are 4 digits in the bike combination
24083 LD A,(HL) Pick up the first digit
24084 AND (HL) Bit 7 of A will remain set if all four written characters matched up with the bike combination digits
24085 INC L
24086 DJNZ 24084
24088 RLCA Was there a match?
24089 JR NC,24114 Jump if not
ERIC has written the bike combination number on a blackboard. Free the bike if it's still chained up.
24091 LD HL,54017 H=211 (bike), L=1
24094 LD A,(HL) A=bike's x-coordinate
24095 CP 224 Is the bike already free?
24097 RET NZ Return if so
24098 LD (HL),100 Place the bike at x-coordinate 100
24100 LD HL,57600 Alter UDG references in the play area to release the bike from the tree
24103 CALL 27672
24106 LD A,100 Add 1000 to the score and print it
24108 CALL 29621
24111 JP 62401 Print the inventory and make a sound effect
The first four characters written on the board by ERIC didn't match the bike combination digits. What about the storeroom combination letters?
24114 LD A,(HL) Pick up the first combination letter
24115 LD B,4 There are 4 letters in the storeroom combination
24117 AND (HL) Bit 7 of A will remain set if all four written characters matched up with the storeroom combination letters
24118 INC L
24119 DJNZ 24117
24121 RLCA Was there a match?
24122 RET NC Return if not
24123 LD L,235 HL=32747 (which holds the inventory flags)
24125 BIT 1,(HL) Has ERIC already got the storeroom key?
24127 RET NZ Return if so
24128 SET 1,(HL) Otherwise give ERIC the key to the storeroom
24130 JR 24106 Add 1000 to the score, print the inventory, and make a sound effect
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