[REBOL] Efficient techniques to parse binary files ?
From: jasonic::panix::com at: 14-Nov-2001 1:22
hmm.. having fun exploring binary PNG files to detect specific characters,
chunks and strings. Using an external tool, TweakPNG I have embedded a REBOL
test script inside the image.
What are some recommended techniques for doing this efficiently?
Looking for general REBOL guidance, but examples are always welcome..
buddha: read/binary %buddha.png
file-length: length? buddha
; == 292962
; starting at position: 292858 here is the test script I want:
{
tEXtScript REBOL []
message: "hello from rebol png!"
send [jasonic--nomadics--org] message
}
So I have been writing mickey-mouse functions with iterations to check
values via
to-char buddha/:position till I find what looks like the begining of text
chunk, then store it in 'chunk and test if chunk = "tEXt" etc
Feels like there must be better way[s].. is sloow too
Here the Problem:
1: Scan through a binary file looking for a chunk = "tEXt"
2: When I do find one, then check if there is special keyword string Script
following it
3: Check if the next string = "REBOL ["
if it then bingo! I want that script for however long it is...
else keep looking for another chunk = "tEXt"
any suggestions ?
thanks
- Jason
