El 02/12/2024 a las 13:16, wkitty42--- via fpc-pascal escribió:
i can do this in python3 but i would rather do it in Pascal because i
have an idea for a project that i think i want to write in Pascal...
Freepascal and possibly Lazarus are my weapons and the only thing i
cannot find is the lz4 ammo library i can use... once i figure this
out, the next goal is figuring out how to read and write the contained
JSON data...
Hello,
If you lz4 blocks does not use dictionary you can try this code to
decompress each block:
*** (TOTALLY UNTESTED CODE) ***
Converted from
https://github.com/jart/cosmopolitan/blob/467504308a103865c058f9a0ac858cc22e72240e/libc/nexgen32e/lz4cpy.c
With this notes:
/**
* Decompresses LZ4 block.
*
* This is a 103 byte implementation of the LZ4 algorithm. Please note
* LZ4 files are comprised of multiple frames, which may be decoded
* together using the wrapper function lz4decode().
*
* @see rldecode() for a 16-byte decompressor
*/
***--------------------------------------------------***
function Lz4Cpy(dest: Pointer; const blockdata: Pointer; blocksize:
SizeUInt): Pointer;
var
op, ip, ipe, match: PByte;
token, length, fifteen, offset, matchlen: Byte;
begin
op := dest;
ip := blockdata;
ipe := ip + blocksize;
fifteen := 15; // Equivalente a pushpop(15) en este caso.
while True do
begin
token := ip^;
Inc(ip);
length := token shr 4;
if length = fifteen then
begin
repeat
Inc(length, ip^);
Inc(ip);
until ip^ <> 255;
end;
Move(ip^, op^, length);
Inc(op, length);
Inc(ip, length);
if NativeUInt(ip) >= NativeUInt(ipe) then
Break;
offset := PWord(ip)^;
Inc(ip, 2);
matchlen := token and fifteen;
if matchlen = fifteen then
begin
repeat
Inc(matchlen, ip^);
Inc(ip);
until ip^ <> 255;
end;
match := op - offset;
Inc(matchlen, 4);
Move(match^, op^, matchlen);
Inc(op, matchlen);
end;
Result := op;
end;
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