Avalon: Routine at D331

D331: Flash the 'MAGIC' text in the bottom left (if Maroc has picked up a spell) and trigger sound effect

Used by the routine at C7EA.

Input
HL	Address pointer (EABC/EABE) to first byte of one of the data sets at 7C00 (the one after the last set copied in the previous routine)

Jump here from C7D0 after copying graphics data to banks at 7C00

If Maroc picks up a spell, the 'Magic' text in the bottom left changes colour for a short time, and a sound is played

flashing indicator when Maroc picks up a spell

D331

LD HL,($EABE)

Address pointer to start of next data set (at 7C00)

D334

LD (HL),$FF

Add end-of-data marker to the first byte of the set

D336

LD ($EB72),HL

Copy address pointer into store

Check if the post-scroll-pickup effect (colour/sound) needs to be actioned:

D339

LD A,($ECA0)

This is the counter byte for flashing the 'MAGIC' text in the bottom left of the screen.

D33C

CP $00

D33E

JR Z,$D368

If it's zero, no need for flashing & playing sound - skip to the next routine

Change the colour of the 'Magic' text in the bottom left of the screen and play a sound.

D340

DEC A

Decrement the 'flashing' counter, and re-store

D341

LD ($ECA0),A

D344

JR NZ,$D348

Check if now zero

D346

LD A,$30

If so, reset the final colour change to yellow (INK 0, PAPER 6), otherwise the counter would make it INK 0, PAPER 0 (invisible).
At the start of the game the lower part of 'MAGIC' is white, but will subsequently be yellow once the first spell is collected (see the animated image on this page).

Change the colour of the word 'MAGIC':

D348

LD DE,$001C

Prepare an offset of 28 character spaces ready to move down to the next line of the screen

D34B

LD C,$02

2 character rows to colour

D34D

LD HL,$5AC2

Screen display address for the top left of the word 'MAGIC'

D350

LD B,$04

4 characters wide

D352

LD (HL),A

Colour the character square (colour = counter byte value)

D353

INC HL

Move right one character square

D354

DJNZ $D352

Repeat x 4

D356

ADD HL,DE

Jump down to the next character row, over to the left again

D357

DEC C

Decrement the row counter

D358

JR NZ,$D350

...And repeat for 2 rows

Play sound effect:

D35A

LD C,$80

Outer loop - duration counter

D35C

LD A,$10

Speaker bit 4 (16)

Speaker toggle loop:

D35E

XOR $10

Toggle speaker bit

D360

OUT ($FE),A

Output sound

D362

LD B,C

Get duration counter

D363

DJNZ $D363

...short pause for duration value of counter

D365

DEC C

Decrement duration counter

D366

JR NZ,$D35E

Repeat loop until sound duration counter = 0