Stormbringer (48k): Routine at 61336

61336: Room drawing: Draw a graphic

Used by the routines at 61214 and 61236.

Input
BC	x- and y-coordinates
HL	(Entry at 61343 only) Address in display file to start drawing

61336

LD (23444),BC

Store x- and y-coordinates of character block currently being drawn at 23444

61340

CALL 63203

Move virtual cursor (bitmap) to display file address for coordinates x=C, y=B and load address into HL

This entry point is used by the routine at 61297.

61343

PUSH HL

Store HL (address in display file to print character)

61344

LD HL,61418

Load HL with 61418 (address of routine to advance HL with apply-horizontal-mirror flag reset)

61347

LD A,(23450)

Load A with apply-horizontal-mirror and apply-vertical-mirror flags

61350

AND 2

If apply-horizontal-mirror flag is reset...

61352

JR Z,61357

...then skip ahead to 61357

61354

LD HL,61521

Load HL with 61521 (address of routine to advance HL with apply-horizontal-mirror flag set)

61357

LD (61416),HL

Change destination for JP instruction at 61415 to value in HL...

61360

POP HL

Restore HL (address in display file to print character)

61361

LD DE,(23447)

Load DE with graphic data address

This entry point is used by the routine at 61390.

61365

LD A,(DE)

Load A with a byte of graphic data

61366

OR A

If data is zero...

61367

JR Z,61390

...then read repeat counter value, x, and draw x rows of reset pixels

61369

CP 255

If data is 255...

61371

JR Z,61411

...then read repeat counter value, x, and draw x rows of set pixels

The three-byte instruction at 61373 is modified by the instructions at 61215, 61238, 61268 and 61299. Initially it is as shown below, however upon modification it can take the following forms:

Instruction	Mirror options	Effect
61215	None	NOP / NOP / NOP (do nothing)
61238	Apply vertical	CALL 61625 (reverse the order of the bits in A)
61268	Apply horizontal	NOP / NOP / NOP (do nothing)
61299	Both	CALL 61625 (reverse the order of the bits in A)