Stormbringer (48k): Routine at 63134

63134: Load HL with display file address for coordinates in BC

Used by the routine at 63040.

Input
B	y-coordinate of axe in pixels
C	x-coordinate of axe in pixels

Output
A	Horizontal pixel offset of axe
HL	Display file address for axe

63134

LD A,C

Load A with remainder, when dividing x-coordinate (pixels) by eight...

63135

AND 7

...i.e. "pixel-within-byte" address

63137

EX AF,AF'

Switch AF and AF'

63138

LD H,0

Load HL with double y-coordinate in pixels...

63140

LD L,B

...

63141

ADD HL,HL

...

63142

LD DE,65140

Point DE at table of display file addresses of start of each pixel row...

63145

ADD HL,DE

...and add HL as offset in HL

63146

LD A,(HL)

Load HL with display file address of start of pixel row at y-coordinate...

63147

INC HL

...

63148

LD H,(HL)

...

63149

LD L,A

...

63150

LD A,C

Load A with x-coordinate in pixels...

63151

RRCA

...and divide by eight to give x-coordinate in characters...

63152

RRCA

...

63153

RRCA

...

63154

AND 31

...

63156

LD C,A

Load BC with x-coordinate in characters...

63157

LD B,0

...

63159

ADD HL,BC

...and add to HL as offset in HL

63160

EX AF,AF'

Switch AF and AF' (A now contains "pixel-within-byte" address)

63161

RET

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