Fast way of converting screen coordinates to HW Sprite control words - Page 3

buzzybee · 10 August 2016, 16:33

Thanks for sharing the conversion code. Will be adapting it for my next project after RESHOOT ... it is already in and working, to be exact ...

Mrs Beanbag · 12 August 2016, 00:27

on the subject of sorting, i prefer insertion sort to bubble sort, it is almost as simple and seems faster. Practical quicksort implementations generally switch to insertion sort when the range is small enough.

Photon · 17 August 2016, 20:38

Forgot about this & had a go, fastest solution is 46 cycles with cheeky preshifted height+attach bit in d2, add a move to keep it constant. d0-d2 in, d1-d2 out.

Code:

	rol.w #8,d1
	add.w d1,d2
	addx.b d2,d2
	lsr.w #1,d0
	move.b d0,d1
	addx.b d2,d2

highpuff · 03 June 2018, 22:45

Seems like the code snippet contains a bug. For example if d1 < 255 (Sprite height) and d2 = 16, the #8 bit of the height will not be set in SPRxCTL.

Made some changes, but sadly also added 4 cycles.

Ed. Which I also found a bug in

Snippet updated and tested

Code:

rol.w #8,d1
add.w d1,d2
addx.b d2,d2
or.b d1,d2
lsr.w #1,d0
addx.b d2,d2
move.b d0,d1

Thanks for a very interesting thread!

Photon · 06 June 2018, 14:54

Yep, found the same OR instruction.

This "conditional bit copy" is necessary for ystart>=256.

17 August 2016, 20:38	#43
Photon Moderator Join Date: Nov 2004 Location: Eksjö / Sweden Posts: 5,602	Forgot about this & had a go, fastest solution is 46 cycles with cheeky preshifted height+attach bit in d2, add a move to keep it constant. d0-d2 in, d1-d2 out. Code: rol.w #8,d1 add.w d1,d2 addx.b d2,d2 lsr.w #1,d0 move.b d0,d1 addx.b d2,d2

03 June 2018, 22:45	#44
highpuff Registered User Join Date: Jan 2014 Location: Göteborg Posts: 43	Seems like the code snippet contains a bug. For example if d1 < 255 (Sprite height) and d2 = 16, the #8 bit of the height will not be set in SPRxCTL. Made some changes, but sadly also added 4 cycles. Ed. Which I also found a bug in Snippet updated and tested Code: rol.w #8,d1 add.w d1,d2 addx.b d2,d2 or.b d1,d2 lsr.w #1,d0 addx.b d2,d2 move.b d0,d1 Thanks for a very interesting thread! Last edited by highpuff; 06 June 2018 at 14:16. Reason: Code snippet updated to working version

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10 August 2016, 16:33	#41
buzzybee Registered User Join Date: Oct 2015 Location: Landsberg / Germany Posts: 526	Thanks for sharing the conversion code. Will be adapting it for my next project after RESHOOT ... it is already in and working, to be exact ...

12 August 2016, 00:27	#42
Mrs Beanbag Glastonbridge Software Join Date: Jan 2012 Location: Edinburgh/Scotland Posts: 2,243	on the subject of sorting, i prefer insertion sort to bubble sort, it is almost as simple and seems faster. Practical quicksort implementations generally switch to insertion sort when the range is small enough.

06 June 2018, 14:54	#45
Photon Moderator Join Date: Nov 2004 Location: Eksjö / Sweden Posts: 5,602	Yep, found the same OR instruction. This "conditional bit copy" is necessary for ystart>=256.

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