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March 1994
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1994.03.14 16:41 "Re: MPW libtiff and LZW", by Niles Ritter
Dwight Kelly (dkelly@etsinc.com) writes,
> Has anyone got LZW & CCITT compression to compile using Apple's
> MPW C compiler? It fails since the compression code needs tables
> larger than 32KB.
>
> dwight kelly
> e.t.s. Inc
I'm pretty sure that Sam has this already, but here's
a set of diffs that will patch tif_lzw.c to dynamically allocate
the tables and free them up later. This patch is for the latest
(v3.3beta002.src.tar.Z) version on sgi.com:
136c136
< code_t dec_codetab[CSIZE];
---
> code_t *dec_codetab; /* [CSIZE] -dynamically allocated */
156c156
< hash_t enc_hashtab[HSIZE];
---
> hash_t *enc_hashtab; /* [HSIZE] -- dynamically allocate */
340a341,350
>
> /* instead of creating a huge struct,
> * we dynamically allocate this array.
> */
> sp->dec_codetab = (code_t*)_TIFFmalloc(sizeof(code_t) * CSIZE);
> if (sp->dec_codetab == NULL) {
> TIFFError("LZWPreDecode",
> "No space for LZW Code Table");
> return (0);
> }
897a908,916
> /* instead of creating a huge struct,
> * we dynamically allocate this array.
> */
> sp->enc_hashtab = (hash_t*)_TIFFmalloc( sizeof(hash_t) * HSIZE);
> if (sp->enc_hashtab == NULL) {
> TIFFError("LZWPreEncode",
> "No space for LZW Hash Table");
> return (0);
> }
1190a1210,1220
> /*
> * free up dynamically allocated memory.
> * This should actually be a method pointer,
> * but it suffices here to test the file
> * mode to figure out which structure is
> * stored in the tif_data member.
> */
> if (tif->tif_mode == O_RDONLY)
> _TIFFfree(((LZWDecodeState*)tif->tif_data)->dec_codetab);
> else
> _TIFFfree(((LZWEncodeState*)tif->tif_data)->enc_hashtab);
I tried once to fix up CCITT as well, but that's a bit more formidable
problem, and of limited usefulness to us since it doesn't handle anything
more than one-bit pixels.
--Niles.