| Routines

8F63: Draw the items in the current cavern and collect any that Willy is touching

Used by the routine at 870E.
8F63 | XOR A | Initialise the attribute of the last item drawn at 8074 to 0x00 (in case there are no items left to draw)
8F64 | LD ($8074),A
8F67 | LD IY,$8075 | Point IY at the first byte of the first item definition at 8075
The item-drawing loop begins here.
8F6B | LD A,(IY+$00) | Pick up the first byte of the item definition
8F6E | CP $FF | Have we dealt with all the items yet?
8F70 | JR Z,$8FBA | Jump if so
8F72 | OR A | Has this item already been collected?
8F73 | JR Z,$8FAE | If so, skip it and consider the next one
8F75 | LD E,(IY+$01) | Point DE at the address of the item's location in the attribute buffer at 5C00
8F78 | LD D,(IY+$02)
8F7B | LD A,(DE) | Pick up the current attribute byte at the item's location
8F7C | AND $07 | Is the INK white (which happens if Willy is touching the item)?
8F7E | CP $07
8F80 | JR NZ,$8F8E | Jump if not
Willy is touching this item, so add it to his collection.
8F82 | LD HL,$842C | Add 100 to the score
8F85 | CALL $90FE
8F88 | LD (IY+$00),$00 | Set the item's attribute byte to 0x00 so that it will be skipped the next time
8F8C | JR $8FAE | Jump forward to consider the next item
This item has not been collected yet.
8F8E | LD A,(IY+$00) | Pick up the item's current attribute byte
8F91 | AND $F8 | Keep the BRIGHT and PAPER bits, and set the INK to 3 (magenta)
8F93 | OR $03
8F95 | LD B,A | Store this value in B
8F96 | LD A,(IY+$00) | Pick up the item's current attribute byte again
8F99 | AND $03 | Keep only bits 0 and 1 and add the value in B; this maintains the BRIGHT and PAPER bits, and cycles the INK colour through 3, 4, 5 and 6
8F9B | ADD A,B
8F9C | LD (IY+$00),A | Store the new attribute byte
8F9F | LD (DE),A | Update the attribute byte at the item's location in the buffer at 5C00
8FA0 | LD ($8074),A | Store the new attribute byte at 8074 as well
8FA3 | LD D,(IY+$03) | Point DE at the address of the item's location in the screen buffer at 6000
8FA6 | LD HL,$80B4 | Point HL at the item graphic for the current cavern (at 80B4)
8FA9 | LD B,$08 | There are eight pixel rows to copy
8FAB | CALL $92D5 | Draw the item to the screen buffer at 6000
The current item definition has been dealt with. Time for the next one.
8FAE | INC IY | Point IY at the first byte of the next item definition
8FB0 | INC IY
8FB2 | INC IY
8FB4 | INC IY
8FB6 | INC IY
8FB8 | JR $8F6B | Jump back to deal with the next item
All the items have been dealt with. Check whether there were any left.
8FBA | LD A,($8074) | Pick up the attribute of the last item drawn at 8074
8FBD | OR A | Were any items drawn?
8FBE | RET NZ | Return if so (some remain to be collected)
8FBF | LD HL,$808F | Ensure that the portal is flashing by setting bit 7 of its attribute byte at 808F
8FC2 | SET 7,(HL)
8FC4 | RET |