Routines
Prev: 37278 Up: Map Next: 37346
37307: Read Terrain Cell
Return the two terrain bytes under the current actor.
Input
IX Actor slot
Output
D First terrain byte
E Second terrain byte
HL Terrain cell index
Return the two terrain bytes under the current actor.
ReadTerrainCell 37307 LD H,(IX+3) Fetch the high byte of the world X.
37310 LD L,(IX+2) Fetch the low byte of the world X.
37313 LD A,H Fetch the high byte.
37314 AND %00011111 Keep only bits 0-4.
37316 LD H,A Write it back to H.
37317 SRA H Divide the world position by 8.
37319 RR L
37321 SRA H
37323 RR L
37325 SRA H
37327 RR L
Read the first terrain byte from the cell.
37329 PUSH HL Stash the cell index on the stack.
37330 LD BC,28672 Point HL at that terrain cell, offset from TerrainData_Active.
37333 ADD HL,BC
37334 LD D,(HL) Fetch the first terrain byte.
37335 POP HL Restore the cell index from the stack, but stash a copy of it on the stack again.
37336 PUSH HL
Step to the next cell, wrapping the index, and read the second terrain byte.
37337 INC HL Move onto the next cell.
37338 LD A,H Fetch the high byte.
37339 AND %00000011 Keep only bits 0-1.
37341 LD H,A Write it back to H.
37342 ADD HL,BC Point HL at that terrain cell.
37343 LD E,(HL) Fetch the second terrain byte.
37344 POP HL Restore the cell index from the stack.
37345 RET Return.
Prev: 37278 Up: Map Next: 37346