Posted: 12/21/2015 10:22 AM
(Edited: 12/21/2015 10:49 AM)
Post subject: Ram "flickers" at Tetris World
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Tavados
Joined: 12/21/2015
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Hi there, hopefully I chose the correct category. So, I want to implement some machine learning and I chose Tetris World for the GBA as platform to do so. By now I got several ram addresses that contain the x and y of the current blocks vertices. Unfortunately the values "flicker" a lot. For example x is 32(goes in steps of 8 when moving left or right) and y is 10(decrements whenever the block goes down) and in the next tick they suddenly are at seemingly arbitrary values and then go back to normal. If I go for 4Byte unsigned they jump to several millions, if I go for signed, then obviously also to negative millions and even if i set the size to 2 or 1 Byte, the values jump around a lot and don't stay at the values that would make sense. Has anybody got an idea, why that happens and how I could fix that? It would suck if I had to make a sanity check for each value every time. Edit: I made a gif, so you can see what i mean. here
Posted: 12/21/2015 10:38 AM
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Invariel
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I don't have access to Tetris Worlds at the moment, so I can't directly test this, but just to clarify, when you are looking at one-byte addresses, are you adding entries for each of the four bytes that you are looking at, or just retaining that list?
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Posted: 12/21/2015 10:52 AM
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Tavados
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When I change to 1Byte, I look at each quarter of the 4Byte address. So when 7754@4Byte flickers, then I will look at 7754,7755,7756,7757@1Byte! Edit: Either way, the important information seems to be only in the first Byte (for 7754 [0,18] would be in sane range) but it "flickers" to several hundreds when looking at 1ByteUnsigned.
Posted: 12/21/2015 12:55 PM
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adelikat
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What is the maximum useful value that x and y would contain? Perhaps the byte is being used for more than 1 thing. For instance, maybe the first 7 bits are the x value, and the 8th is being used for some flag.
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Posted: 12/21/2015 1:03 PM
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Tavados
Joined: 12/21/2015
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x goes from 0 to 9 and y goes from -1 to 19 (-1 is for when e.g. the square spawns at the very top, only showing the lower half). As I said I also looked at the values Byte by Byte and it doesn't make sense either. For example the x-coordinate of part0 (of the 4 part object) is at 0x7750, then the actual position is in 7750 itself, not in 7751,7752,7753. Also that value jumps from e.g. 7 to 0 then to 24 etc. Is the IWRAM the only legit domain to find those values?
Posted: 12/21/2015 1:20 PM
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TASeditor
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You set them to 4 bytes, try 1 or 2 bytes.
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Posted: 12/21/2015 1:37 PM
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Tavados
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I said twice that I did that already, maybe I'm formulating it wrong. I tested 4Bytes, I tested 2Bytes, I tested 1Byte. In each case the memory jumps around to values that don't make sense.
Posted: 12/21/2015 5:04 PM
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zeromus
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This is completely typical results. You're looking at the stack. It's full of temporary values. For this game, look in EWRAM instead. $5040 seems promising
Posted: 12/22/2015 4:37 PM
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Tavados
Joined: 12/21/2015
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Believe it or not, but I already looked to the EWRAM. Yea, 005040 contains x and 005044 contains y, but only of the center of rotation. There doesn't seem to be x and y for all parts, which I definately need. With another variable telling the rotation of the block it would technically be possible aswell, although I really hope to straightup get four x and y coordinates.
Posted: 12/22/2015 4:53 PM
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Tavados wrote:
With another variable telling the rotation of the block it would technically be possible aswell, although I really hope to straightup get four x and y coordinates.
You can hope all you want. If the game calculates it by using the center of rotation, rotation position and block id, then there won't be any useful address for you to hope for. This is where a lua script can solve the issue by recreating how the game calculates the positions. Or you can hope.
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