Just another Coleco Programer

[Mike Harris]

OK, hate to say I stayed up last night but I did.

I had to write my new map routine and I can say I am done with it.
4 bytes per row at 24 rows

 

Here is a sample code that reads the bits

BIT_DRAW:
PUSH DE
PUSH BC
LD DE, BLOCK
LD C, A
BIT 0,C
JR Z, RD_BIT_1
CALL DO_IT
RD_BIT_1:
INC HL
BIT 1,C
JR Z, RD_BIT_2
CALL DO_IT
RD_BIT_2:
INC HL
BIT 2,C
JR Z, RD_BIT_3
CALL DO_IT
RD_BIT_3:
INC HL
BIT 3,C
JR Z, RD_BIT_4
CALL DO_IT
RD_BIT_4:
INC HL
BIT 4,C
JR Z, RD_BIT_5
CALL DO_IT
RD_BIT_5:
INC HL
BIT 5,C
JR Z, RD_BIT_6
CALL DO_IT
RD_BIT_6:
INC HL
BIT 6,C
JR Z, RD_BIT_7
CALL DO_IT
RD_BIT_7:
INC HL
BIT 7,C
JR Z, END_THIS
CALL DO_IT
END_THIS:
INC HL
POP BC
POP DE
RET

 

It took me a couple of hours and I had to write it into long form then I shortened it into a loop.

You may say why but I went from of 12k down to 4 just by saving map data.
My character is already moving and I have all my sprite data.
So, I am estimating this will be either an 8 or 12k before more optimizations.

[Mike Harris]

Refined my routine to 2 bytes per map data with mirror.

 

Great routine to reverse any 8 bit number.

 

Got the idea from the original OS7 Reverse Sprite Routine listed in my ADAM Technical Reference Manual I bought back in 84.

 

MIRROR:
LD b,8 ; All 8 bits
LD l,a ; Byte to be reverse
REVERSE_ME:
RL l
RRA
DJNZ REVERSE_ME
RET ; return from call

Edited December 23, 2018 by Mike Harris