Routines
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AED3: Play Footstep Sound
Used by the routines at HandleOutlaw, HandleBystander and MovePlayerForward.
Plays a burst of noise when a walking figure puts a foot down, which is when bits 0 and 1 of the flags of the object have both just become set.
Input
A The flags of the object before it was moved
IX The address of the object
Return unless both walk bits have just become set.
PlayFootstepSound AED3 BIT 0,A Test bit 0 of the old flags.
AED5 RET NZ Return if it was already set.
AED6 BIT 0,(IX+$07) Return if bit 0 of the flags is not set now.
AEDA RET Z
AEDB BIT 1,(IX+$07) Return if bit 1 of the flags is not set now.
AEDF RET Z
Play a burst of pulses.
AEE0 LD C,$10 Set the number of pulses.
PlayFootstepSound_Loop AEE2 LD A,C Fetch the number of the pulse.
AEE3 XOR %01110110 Change it to make a different length for each pulse.
AEE5 LD B,A Use it as the length of the pulse.
AEE6 CALL PlaySquareWave Play the pulse.
AEE9 DEC C Count down the pulses.
AEEA JR NZ,PlayFootstepSound_Loop Loop back until all of the pulses have been played.
AEEC RET Return.
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