Modifying a copperlist

CmdrVimes · 04 September 2010, 01:50

Hi Guys,
Can anyone help me find the instructions that I need to be able to modify a copper list during the vertical blank?

I would like to be able to move a copper bar up and down the screen. I found some source code for this but it involved three copper bars and a lot of labelled sections in the source and I was unable to follow it.

pmc · 04 September 2010, 08:21

Hey CmdrVimes

You can modify a copper list during vertical blank by moving new values to the list.

If you think about the format of a copper background colour change in the copper list it is: wait for a scanline, move a value to the background colour register.

So, if at vertical blank you move a new scanline value to the copper wait instruction or a new colour value to the copper move instruction, the bar will have changed in time for displaying during the next frame. In other words, the bar will have moved.

Does that give you enough to go on...?

CmdrVimes · 06 September 2010, 11:30

Hi,
Thanks. I decided to have another look at the source code I mentioned and it makes more sense 2nd and 3rd times around.

I have just one question - is it always necessary to use interrupts to detect the v-blank?

Ok, two questions - I feel that I could use a really good 68k ASM reference that covers the Amiga's ASM language. I have the Amiga hardware ref already but every now and then I trip over an ASM command that I'm not familiar with. Do you have any suggestions?

pmc · 06 September 2010, 11:46

Watcha mate

Quote:

Originally Posted by CmdrVimes

is it always necessary to use interrupts to detect the v-blank?

No. You can just wait for a vertical blank by manually waiting for the beam position to be in the vertical blank area by polling the vposr / vhposr regs.

Quote:

Originally Posted by CmdrVimes

Ok, two questions - I feel that I could use a really good 68k ASM reference that covers the Amiga's ASM language. I have the Amiga hardware ref already but every now and then I trip over an ASM command that I'm not familiar with. Do you have any suggestions?

The Amiga's asm language is 68k asm so any text that covers 68k asm will be fine. My favourite is:

68000, 68010, 68020 Primer published by SAMS written by Kelly-Bootle & Fowler available very cheaply from http://www.abebooks.co.uk

StingRay · 06 September 2010, 11:52

Quote:

Originally Posted by CmdrVimes

Ok, two questions - I feel that I could use a really good 68k ASM reference that covers the Amiga's ASM language. I have the Amiga hardware ref already but every now and then I trip over an ASM command that I'm not familiar with. Do you have any suggestions?

A good reference is the official Motorola 68000 Programmer's Reference Manual.

CmdrVimes · 06 September 2010, 12:08

@pmc & @StingRay
Thanks guys. I must say, you blokes are REALLY fast. I get slower responses verbally on some occasions than I get from this forum!

04 September 2010, 01:50	#1
CmdrVimes Badge 177 Join Date: Aug 2010 Location: Mirfield / UK Posts: 77	Modifying a copperlist Hi Guys, Can anyone help me find the instructions that I need to be able to modify a copper list during the vertical blank? I would like to be able to move a copper bar up and down the screen. I found some source code for this but it involved three copper bars and a lot of labelled sections in the source and I was unable to follow it.

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04 September 2010, 08:21	#2
pmc gone Join Date: Apr 2007 Location: completely gone Posts: 1,596	Hey CmdrVimes You can modify a copper list during vertical blank by moving new values to the list. If you think about the format of a copper background colour change in the copper list it is: wait for a scanline, move a value to the background colour register. So, if at vertical blank you move a new scanline value to the copper wait instruction or a new colour value to the copper move instruction, the bar will have changed in time for displaying during the next frame. In other words, the bar will have moved. Does that give you enough to go on...?

06 September 2010, 11:30	#3
CmdrVimes Badge 177 Join Date: Aug 2010 Location: Mirfield / UK Posts: 77	Hi, Thanks. I decided to have another look at the source code I mentioned and it makes more sense 2nd and 3rd times around. I have just one question - is it always necessary to use interrupts to detect the v-blank? Ok, two questions - I feel that I could use a really good 68k ASM reference that covers the Amiga's ASM language. I have the Amiga hardware ref already but every now and then I trip over an ASM command that I'm not familiar with. Do you have any suggestions?

06 September 2010, 12:08	#6
CmdrVimes Badge 177 Join Date: Aug 2010 Location: Mirfield / UK Posts: 77	@pmc & @StingRay Thanks guys. I must say, you blokes are REALLY fast. I get slower responses verbally on some occasions than I get from this forum!

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