[steem] The come back of the Snapshot
- From: BRINGER Pascal <bringerp@xxxxxxxx>
- To: steem@xxxxxxxxxxxxx
- Date: Fri, 27 Dec 2002 10:57:13 +0100 (CET)
Hello everbody, and merry Xmas !
The subject of this mail is the... memory snapshot !
lol
I have take some mail from a conversation that
describe a little the format of the snapshot that
Steem Engine creates (sorry for my bad english).
"Well when I said 'incredibly complex' I was slightly
wrong, maybe 'really
stupidly simple and rubbish' would be better! :-)
Basically from the start
of the encoded area it first reads a status word, if
this is < 0x8000 then
it reads that many words from the file. If it is >
0x8000 then it reads 1
word from the file and repeats it (status & 0x7fff)
times. It keeps doing
this until status=0xffff."
[Russ]
"Doesn't sound too bad. I had to reverse the snapshot
file as it was read in,
as byte 0 of the ST memory seemed to be at the end of
the file. So I take it
the RLE is not affected by this(Reverse encoding from
the end of the file).
I should noticed the variable file lengths earlier.
:0P"
[Ian]
"Oh yeah, I forgot about this, makes things harder.
The memory is stored
backwards but is encoded forwards, if you get my
drift. So the first word of
RAM from the start of the snapshot is a status word
but when you expand the
info you get the last bytes of ST memory. This is
going to be very difficult
to get round, I'll try to think of the easiest way for
you to do it."
[Russ]
The snapshot is divided into 2 parts:
-The Header
-Datas (the st memory), writted from the end of the st
memory to the beginning (so in reverse order, but the
high bit on left and low bit on right, cool)
Here come my questions, (if you prefere make a
summary, i'll be happy to and all who want use the
snapshot too ^^ ):
- can u correct me if something is wrong in the
explanation above ?
- Is the Header RLE compressed too (so all the
snapshot) or just the Datas ? If i look at the file,
it seems only Datas.
- where's the variable file length ? is it an offset
to the beginning of the datas (st memory) ?
- can u give your class, information or the structure
of the Header ?
- can u think you are going to change a lot of things
for the snapshot in the next release ? (if so we can
wait for it)
- perhaps can u raise the size of the dump in the
debug to a variable size ? (so no rle compression and
no header... cool ^^ )
I hope my questions are well formed and not too lazy.
I thx u a lot for all, and good job !
Pascal (French)
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