Z80:Optimization - Revision history

KermMartian at 08:23, 6 February 2016

2016-02-06T08:23:17Z

← Older revision		Revision as of 08:23, 6 February 2016
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	= Conclusion =		= Conclusion =

	From this point on, you may be perfectly happy with your program. It works, runs at a decent speed and is also smaller than it use to be. What more could there be to do? [[Z80:Polishing~~-it-up~~\|Read on]] to find out what else you need to do before you decide to release your program to the general public.		From this point on, you may be perfectly happy with your program. It works, runs at a decent speed and is also smaller than it use to be. What more could there be to do? [[Z80:Polishing\|Read on]] to find out what else you need to do before you decide to release your program to the general public.

	{{lowercase}}		{{lowercase}}
	[[Category:Z80 Assembly]]		[[Category:Z80 Assembly]]
	[[Category:Z80 Heaven]]		[[Category:Z80 Heaven]]

KermMartian at 06:32, 5 February 2016

2016-02-05T06:32:05Z

Show changes

KermMartian: Adjusted lowercase z80

2016-02-03T21:12:32Z

Adjusted lowercase z80

← Older revision		Revision as of 21:12, 3 February 2016
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	= Conclusion =		= Conclusion =

	From this point on, you may be perfectly happy with your program. It works, runs at a decent speed and is also smaller than it use to be. What more could there be to do? [[~~z80~~:Polishing\|Read on]] to find out what else you need to do before you decide to release your program to the general public.		From this point on, you may be perfectly happy with your program. It works, runs at a decent speed and is also smaller than it use to be. What more could there be to do? [[Z80:Polishing\|Read on]] to find out what else you need to do before you decide to release your program to the general public.

	{{lowercase}}		{{lowercase}}
	[[Category:~~z80~~ Assembly]]		[[Category:Z80 Assembly]]
	[[Category:~~z80~~ Heaven]]		[[Category:Z80 Heaven]]

KermMartian: /* xor a vs. ld a,0 */

2016-02-03T20:19:41Z

xor a vs. ld a,0

← Older revision		Revision as of 20:19, 3 February 2016
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	== xor a vs. ld a,0 ==		== xor a vs. ld a,0 ==

	A simple way to set a to zero. Don't use this if you want to preserve the ~~accumulator~~.		A simple way to set a to zero. Don't use this if you want to preserve the flags.

	== or a vs. cp 0 ==		== or a vs. cp 0 ==

KermMartian: Created page with "After you've worked the bugs out, you may if you wish make your program smaller and run faster. This section is dedicated to just that purpose. Although there are a lot of thi..."

2016-02-03T20:19:22Z

Created page with "After you've worked the bugs out, you may if you wish make your program smaller and run faster. This section is dedicated to just that purpose. Although there are a lot of thi..."

New page

After you've worked the bugs out, you may if you wish make your program smaller and run faster. This section is dedicated to just that purpose. Although there are a lot of things you can do, here are some general things that can help:

= Code replacements =

== xor a vs. ld a,0 ==

A simple way to set a to zero. Don't use this if you want to preserve the accumulator.

== or a vs. cp 0 ==

It's smaller, and give you the same results.

== Cursor/pen ==

ld hl,$0100 ;$01 is the row, and $00 is the column
ld (curRow),hl
ld (penCol),hl

This is much more efficient if you're going to change both cursor/pen positions. Because curCol is right after curRow (and penRow is right after penCol), you can use a 16-bit register to load both at once.

= PutS =

Something you may or may not know, it is that PutS and any other variation modifies HL to point to the byte after the null-term. This is very useful, especially when displaying multiple items to different locations on the screen without having to load string after string into hl.

ld hl,txtTest
bcall(_PutS)
ld de,$0100
ld (curRow),de
ld hl,txtTest2
bcall(_PutS)
;...

txtTest:
.db "Test",0
txtTest2:
.db "Test2",0

can be

ld hl,txtTest
bcall(_PutS)
ld de,$0100
ld (curRow),de
;we don't need "ld hl,txtTest2", because hl already points to txtTest2
bcall(_PutS)
;...

txtTest:
.db "Test",0
;txtTest2 ;Optional, doesn't affect speed or size here
.db "Test2",0

It also allows you to display strings through a loop say, for a high score board.

high:
ld b,8
ld de,0
ld (curRow),de
ld hl,txtHigh
highloop:

push hl
push de
ld a,(hl)
ld h,0
ld l,a
bcall(_DispHL)
pop de
pop hl

inc hl

bcall(_PutS)

inc e
ld d,0
ld (curRow),de
djnz highloop

bcall(_GetKey)
ret

txtHigh:
.db 20,"HIGH SCORE!",0
txt2nd:
.db 19,"HIGH SCORE!",0
txt3rd:
.db 18,"HIGH SCORE!",0
txt4th:
.db 17,"HIGH SCORE!",0
txt5th:
.db 16,"HIGH SCORE!",0
txt6th:
.db 15,"HIGH SCORE!",0
txt7th:
.db 14,"HIGH SCORE!",0
txt8th:
.db 13,"HIGH SCORE!",0

= Conclusion =

From this point on, you may be perfectly happy with your program. It works, runs at a decent speed and is also smaller than it use to be. What more could there be to do? [[z80:Polishing|Read on]] to find out what else you need to do before you decide to release your program to the general public.

{{lowercase}}
[[Category:z80 Assembly]]
[[Category:z80 Heaven]]