Martianoids: Routine at A12D

A12D: Try Move

Used by the routines at MoveSpark, MoveThief, MoveProgramPacket, MoveHunter, MovePellet and MoveDome.

Moves an entity in the direction that it is heading, using MoveEntity, and then tests whether it has been blocked. An entity that is blocked by a cell of type 0F is allowed to carry on.

Input
B	Number of steps that can still be taken
DE	X position
HL	Y position

Output
A	The type of the cell that is blocking the entity
F	The zero flag is set if the entity can carry on

TryMove

A12D

CALL MoveEntity

Move using MoveEntity, and return if the entity can carry on.

A130

RET Z

A131

PUSH HL

Save the Y position.

A132

LD HL,($962E)

Fetch the address of the cell that blocked the entity...

A135

LD A,(HL)

...and fetch its type.

A136

AND $0F

Keep the current type of the cell.

A138

POP HL

Restore the Y position.

A139

CP $0F

Return if the cell is not type 0F.

A13B

RET NZ

A13C

LD HL,($9655)

Otherwise restore the Y position that the entity had before the move...

A13F

LD DE,($9653)

...and the X position.

A143

RET

Return with the zero flag set.