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Commit 8b235f2f authored by yalin wang's avatar yalin wang Committed by Linus Torvalds
Browse files

zlib_deflate/deftree: remove bi_reverse() 



Remove bi_reverse() and use generic bitrev32() instead - it should have
better performance on some platforms.

Signed-off-by: default avataryalin wang <yalin.wang2010@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e4e29dc4

lib/zlib_deflate/deftree.c

+3 −3
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ 
/* #include "deflate.h" */



#include <linux/zutil.h>

#include <linux/bitrev.h>

#include "defutil.h"



#ifdef DEBUG_ZLIB
@@ -146,7 +147,6 @@ static void send_all_trees (deflate_state *s, int lcodes, int dcodes, 
static void compress_block (deflate_state *s, ct_data *ltree,

                           ct_data *dtree);

static void set_data_type  (deflate_state *s);

static unsigned bi_reverse (unsigned value, int length);

static void bi_windup      (deflate_state *s);

static void bi_flush       (deflate_state *s);

static void copy_block     (deflate_state *s, char *buf, unsigned len,
@@ -284,7 +284,7 @@ static void tr_static_init(void) 
    /* The static distance tree is trivial: */

    for (n = 0; n < D_CODES; n++) {

        static_dtree[n].Len = 5;

        static_dtree[n].Code = bi_reverse((unsigned)n, 5);

        static_dtree[n].Code = bitrev32((u32)n) >> (32 - 5);

    }

    static_init_done = 1;

}
@@ -520,7 +520,7 @@ static void gen_codes( 
        int len = tree[n].Len;

        if (len == 0) continue;

        /* Now reverse the bits */

        tree[n].Code = bi_reverse(next_code[len]++, len);

        tree[n].Code = bitrev32((u32)(next_code[len]++)) >> (32 - len);



        Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",

             n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));

lib/zlib_deflate/defutil.h

+0 −16
Original line number Diff line number Diff line
@@ -292,22 +292,6 @@ void zlib_tr_stored_type_only (deflate_state *); 
    put_byte(s, (uch)((ush)(w) >> 8)); \

}



/* ===========================================================================

 * Reverse the first len bits of a code, using straightforward code (a faster

 * method would use a table)

 * IN assertion: 1 <= len <= 15

 */

static inline unsigned bi_reverse(unsigned code, /* the value to invert */

				  int len)       /* its bit length */

{

    register unsigned res = 0;

    do {

        res |= code & 1;

        code >>= 1, res <<= 1;

    } while (--len > 0);

    return res >> 1;

}



/* ===========================================================================

 * Flush the bit buffer, keeping at most 7 bits in it.

 */