Routines
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CBBD: Switch to a new room
Used by the routines at C881, D3EC, D4B5, D567, D607, DBEE and E663.
Input
A New room
CBBD LD ($CFCA),A Get the current room. (CFCA).
CBC0 ADD A,A Multiply it by 4 and put it in HL.
CBC1 ADD A,A
CBC2 LD L,A
CBC3 LD H,$00
CBC5 LD C,L Copy HL to BC.
CBC6 LD B,H
CBC7 ADD HL,HL Multiply the address by 4 to get a suitable offset.
CBC8 ADD HL,BC
CBC9 LD DE,$69E6 Add the base address for room offsets (69E6)
CBCC ADD HL,DE
CBCD PUSH HL Put the pointer to the actual room in IX.
CBCE POP IX
CBD0 LD A,(IX+$04) Get the flags for this room?
CBD3 AND $C0 Get bits 6-7 (wall information).
CBD5 RRCA Shift this three bits to the right to get a suitable offset and put it in BC.
CBD6 RRCA
CBD7 RRCA
CBD8 LD C,A
CBD9 LD HL,$6C26 Add the base address for wall data. (6C26).
CBDC ADD HL,BC
CBDD LD BC,$0008 8 bytes to copy.
CBE0 LD DE,$CFD1 Copy to the working buffer. (CFD1)
CBE3 LDIR
CBE5 EXX Store the shadow set of HL, DE and BC.
CBE6 PUSH HL
CBE7 PUSH DE
CBE8 PUSH BC
CBE9 EXX
CBEA CALL $E820 Clear the screen.
CBED CALL $ED00 Print the room's UDGs.
CBF0 CALL $DCC1 Draw any food.
CBF3 CALL $CC36 Draw the river if it's here.
CBF6 CALL $E544 Display moving objects.
CBF9 CALL $CE76 Draw any additional objects if relevant.
CBFC LD A,($CFCA) Put the current room in B.
CBFF LD B,A
CC00 CALL $F3EC Draw any special objects.
CC03 CALL $C8FF Put Dan in the right place.
CC06 LD HL,$C87C Get the lift co-ordinate.
CC09 LD A,(HL)
CC0A CP $1C If it's greater than the maximum 1C then set it to that.
CC0C JR NC,$CC10
CC0E LD (HL),$1C
Handle if the room has been visited, and if not, increment the running total.
CC10 BIT 7,(IX+$0B) Has the room been visited?
CC14 JR NZ,$CC30 Jump forward if it has.
CC16 SET 7,(IX+$0B) Set the "room visited" flag.
CC1A LD HL,$CE56 Set HL to the relevant part of the "screens visited" message (CE53).
CC1D LD A,(HL) Is the current digit 9?
CC1E CP $09
CC20 JR Z,$CC25 If so, need to accomodate decimal overflow.
CC22 INC (HL) Otherwise increment number of screens visited and move on.
CC23 JR $CC30
Accomodate decimal overflow in the number of screens visited.
CC25 LD (HL),$00 Set the digit to 0.
CC27 DEC HL Move to the previous digit (ie: more significant)
CC28 INC (HL) Increment that.
CC29 LD A,(HL) Have we reached the maximum of 0280?
CC2A CP $28
CC2C JR NZ,$CC30 Jump forward if we haven't.
CC2E LD (HL),$01 Otherwise something's gone wrong, either a bug or hacking, so set back to 1.
All done with setting up the room.
CC30 EXX Restore the shadow registers and return.
CC31 POP BC
CC32 POP DE
CC33 POP HL
CC34 EXX
CC35 RET
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