Messages in this thread | | | Date | Fri, 24 Feb 2006 13:52:05 -0800 | From | John Reiser <> | Subject | Re: [PATCH 5/7] inflate pt1: cleanup Huffman table code |
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> Index: 2.6.16-rc4-inflate/lib/inflate.c > =================================================================== > --- 2.6.16-rc4-inflate.orig/lib/inflate.c 2006-02-22 17:16:07.000000000 -0600 > +++ 2.6.16-rc4-inflate/lib/inflate.c 2006-02-22 17:16:08.000000000 -0600 > @@ -117,12 +117,12 @@ > an unused code. If a code with e == 99 is looked up, this implies an > error in the data. */ > struct huft { > - u8 e; /* number of extra bits or operation */ > - u8 b; /* number of bits in this code or subcode */ > union { > - u16 n; /* literal, length base, or distance base */ > - struct huft *t; /* pointer to next level of table */ > - } v; > + u16 val; /* literal, length base, or distance base */ > + struct huft *next; /* pointer to next level of table */ > + }; > + u8 extra; /* number of extra bits or operation */ > + u8 bits; /* number of bits in this code or subcode */ > };
How aggressive do you want to be? About 3.7 years ago in http://freshmeat.net/projects/gzip_x86/ I published: ----- typedef unsigned short huft_ndx; /* index>>1 */ struct huft { uch e; /* number of extra bits or operation */ uch b; /* number of bits in this code or subcode */ union { ush n; /* literal, length base, or distance base */ huft_ndx t; /* index>>1 of next level of table */ } v; }; ----- which makes 4==sizeof(struct huft) and enables manipulation by 32-bit fetch, exposing 'e' [extra] and 'b' [bits] in x86 byte registers for fewer shift-and-mask operations. The struct huft can be managed as a stack of maximum length 1014.
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