GPUOBJECT w/o interrupt enabling

[42bs]

I tried to use a GPUOBJECT w/o enabling the interrupt. This works in VJ 2.1.3 but it does not seem to work on real hardware.

I use GPUOBJECTs with JagTris with interrupt.

Anyone tried it also w/o interrupt enabling?

[SCPCD]

The Object Processor is not aware of the interrupts enabled (or not) of the GPU :

It works as a separate component, and so, the GPUObject will pause the ObjectProcessor and wait for a OBF write, wathever the GPU configuration.

 

 

[42bs]

From what I see, the interrupt is not latched.

I have a GPUOBJECT at the end of the screen (by using BRANCH objects) and clear the latch before releasing the OP. But the bit does not get set.

I will try other interrupts.

[SCPCD]

Indeed : Latches bit are not setted if the Interrupt bit is not enabled.

You can't use Bit Banging to detect interrupts, if it's what you would like to do :)

 

[42bs]

Yes, I did hope to get rid of the 68k. I made an intro where I just check the bitmap address to know when it is done, but this does not work for reloading the OP list.

But a least it avoids flickering when I clear the screen for the next frame.

But I have an idea to use the interrupt without spending to much space.

Edited March 24, 2022 by 42bs

[SCPCD]

Maybe you can use the OB[0-3] registers to detect a specific pattern that match the GPUObject/StopObject by setting the #data field of one or both.

 

[42bs]

The interrupt version works, but setting up the interrupt handling eats a lot of space and the GPUOBJECT bug (fireing for _every_ line) forces to add three branch objects.

 

[JagMod]

This is how I build a list to handle the GPUOBJECT

It only interrupts the GPU once per frame at the end of the display (VDE)

I run this with the 68k shut off.

p1..p8 addresses are phrases in memory

 

p1  --------
p2  -------- GPU Int Obj
p3  -------- STOP Obj
p4  -------- Br = VDE (to GPU Int)
p5  -------- Br < VDB (to Stop)
p6  -------- Br > VDE (to Stop)
p7  -------- Normal Bitmap (to Stop)
p8  --------

 

OP points to p4

 

It looks shifted down by a phrase,

this is so the bitmap object is on a double phrase alignment.

Branches can fall through to next phrase if branch not taken.

Edited March 25, 2022 by JagMod

[42bs]

Nice idea to jump 'backwards'. Nowhere is written that link needs always go forward.

But for the intro I run out of memory, so I did

P0 bitmap 

P2 branch VC < vde => P4

P3 GPU object 

P4 stop 

Since the OP stops on the GPU object, there is only one interrupt.