[Patch] 2.5.70-bk11 zlib merge #3 inffast.c

From: Jörn Engel (joern@wohnheim.fh-wedel.de)
Date: Fri Jun 06 2003 - 15:00:51 EST


Hi Linus!

This patch took me only 30 minutes to verify, too easy! :)

Most of it is reformatting, but the functional bits should fix real
problems. A loop is introduced, just like in the turboc patch and one
of the three condition bodies has been expanded.

Jörn

-- 
Fancy algorithms are slow when n is small, and n is usually small.
Fancy algorithms have big constants. Until you know that n is
frequently going to be big, don't get fancy.
-- Rob Pike

--- linux-2.5.70-bk11/lib/zlib_inflate/inffast.c~zlib_merge_inffast 2003-06-06 15:56:15.000000000 +0200 +++ linux-2.5.70-bk11/lib/zlib_inflate/inffast.c 2003-06-06 21:53:50.000000000 +0200 @@ -90,28 +90,41 @@ /* do the copy */ m -= c; - if ((uInt)(q - s->window) >= d) /* offset before dest */ - { /* just copy */ - r = q - d; - *q++ = *r++; c--; /* minimum count is three, */ - *q++ = *r++; c--; /* so unroll loop a little */ - } - else /* else offset after destination */ + r = q - d; + if (r < s->window) /* wrap if needed */ { - e = d - (uInt)(q - s->window); /* bytes from offset to end */ - r = s->end - e; /* pointer to offset */ - if (c > e) /* if source crosses, */ + do { + r += s->end - s->window; /* force pointer in window */ + } while (r < s->window); /* covers invalid distances */ + e = s->end - r; + if (c > e) { - c -= e; /* copy to end of window */ + c -= e; /* wrapped copy */ do { - *q++ = *r++; + *q++ = *r++; } while (--e); - r = s->window; /* copy rest from start of window */ + r = s->window; + do { + *q++ = *r++; + } while (--c); + } + else /* normal copy */ + { + *q++ = *r++; c--; + *q++ = *r++; c--; + do { + *q++ = *r++; + } while (--c); } } - do { /* copy all or what's left */ - *q++ = *r++; - } while (--c); + else /* normal copy */ + { + *q++ = *r++; c--; + *q++ = *r++; c--; + do { + *q++ = *r++; + } while (--c); + } break; } else if ((e & 64) == 0) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/



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