| Routines

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