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restrict lzw dict to 4096 entries (maxfieldsize=12bits)

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git-svn-id: svn://svn.code.sf.net/p/actiongame/code/trunk/ac@2734 e016b1c5-ed68-44aa-a2f7-31cac88cffde
This commit is contained in:
driAn
2008-09-22 20:14:17 +00:00
parent 009bde54f4
commit cbca3399a6
1 changed files with 40 additions and 11 deletions
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source/src/lzwcompression.cpp
+40 -11
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@@ -120,8 +120,9 @@ struct bitbuf : databuf<uchar>
struct lzwbuffer : bitbuf
{
lzwdirectory dictionary;
const int maxfieldsize;
lzwbuffer(uchar *buf, size_t maxlen) : bitbuf(buf, maxlen)
lzwbuffer(uchar *buf, size_t maxlen) : bitbuf(buf, maxlen), maxfieldsize(12)
{
dictionary.fillstaticentries();
}
@@ -185,7 +186,7 @@ struct lzwbuffer : bitbuf
// increase bitfieldsize
int supporteddictsize = (1<<fieldsize);
if(dictionary.length()>supporteddictsize) fieldsize++;
if(dictionary.length()>supporteddictsize && fieldsize<maxfieldsize) fieldsize++;
}
}
@@ -241,7 +242,7 @@ struct lzwbuffer : bitbuf
// adjust bitfieldsize
int supporteddictsize = (1<<fieldsize);
if(dictionary.length()>=supporteddictsize) fieldsize++;
if(dictionary.length()>=supporteddictsize && fieldsize<maxfieldsize) fieldsize++;
}
dictionary.resettostaticentries();
@@ -250,6 +251,8 @@ struct lzwbuffer : bitbuf
#ifdef _DEBUG
#ifndef STANDALONE
void testbitbuf()
{
// test bitbuf struct using different fieldsizes and random data
@@ -297,6 +300,7 @@ void testbitbuf()
void testlzw()
{
const int NUMRUNS = 3;
const int TESTBUFSIZE = 2*1024*1024;
// input data
s_sprintfd(txt)("TOBEORNOTTOBEORTOBEORNOT#");
@@ -306,8 +310,8 @@ void testlzw()
loopi(2048) staticbuf[i] = (uchar) (i % 256);
const char *testnames[] = { "text", "random data", "static data" };
uchar *ibuf[] = { (uchar*)&txt, rndbuf, staticbuf };
size_t len[] = { strlen(txt), 1024, 2048 };
uchar *ibuf[] = { (uchar*)&txt, rndbuf, staticbuf};
size_t len[] = { strlen(txt), 1024, 2048};
loopj(NUMRUNS)
{
@@ -320,9 +324,9 @@ void testlzw()
lzwbuffer inbuf(ibuf[i], len[i]);
// compressed
uchar cbuf[8*1024];
memset(cbuf, 0, 8*1024);
lzwbuffer compressed(cbuf, 8*1024);
uchar *cbuf = new uchar[TESTBUFSIZE];
memset(cbuf, 0, TESTBUFSIZE);
lzwbuffer compressed(cbuf, TESTBUFSIZE);
starttime = SDL_GetTicks();
inbuf.compress(compressed);
@@ -330,9 +334,9 @@ void testlzw()
conoutf("compressed %d bytes to %d bytes in %d milliseconds", len[i], compressed.len, endtime-starttime);
// decompressed
uchar dbuf[8*1024];
memset(dbuf, 0, 8*1024);
lzwbuffer decompressed(dbuf, 8*1024);
uchar *dbuf = new uchar[TESTBUFSIZE];
memset(dbuf, 0, TESTBUFSIZE);
lzwbuffer decompressed(dbuf, TESTBUFSIZE);
starttime = SDL_GetTicks();
compressed.decompress(decompressed);
@@ -341,6 +345,9 @@ void testlzw()
// verify
ASSERT(!memcmp(ibuf[i], dbuf, len[i]));
delete[] cbuf;
delete[] dbuf;
}
}
}
@@ -348,4 +355,26 @@ void testlzw()
COMMAND(testbitbuf, ARG_NONE);
COMMAND(testlzw, ARG_NONE);
#endif
void lzwout(void *data, int len)
{
static FILE *lzw = NULL, *normal = NULL;
if(!lzw)
{
lzw = openfile("out.lzw", "wb");
normal = openfile("out.normal", "wb");
}
ASSERT(lzw && normal);
fwrite(data, 1, len, normal);
lzwbuffer b((uchar*)data, len);
uchar cbuf[512*1024];
lzwbuffer c(cbuf, 512*1024);
b.compress(c);
fwrite((void*) c.buf, 1, c.len, lzw);
}
#endif