From 06f35d8aa46e4cf48d4118d0ea8e001c3890804f Mon Sep 17 00:00:00 2001 From: yalin wang Date: Wed, 9 Sep 2015 15:39:18 -0700 Subject: [PATCH] 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: yalin wang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/zlib_deflate/deftree.c | 6 +++--- lib/zlib_deflate/defutil.h | 16 ---------------- 2 files changed, 3 insertions(+), 19 deletions(-) diff --git a/lib/zlib_deflate/deftree.c b/lib/zlib_deflate/deftree.c index ddf348299f244..9b1756b12743f 100644 --- a/lib/zlib_deflate/deftree.c +++ b/lib/zlib_deflate/deftree.c @@ -35,6 +35,7 @@ /* #include "deflate.h" */ #include +#include #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)); diff --git a/lib/zlib_deflate/defutil.h b/lib/zlib_deflate/defutil.h index b640b6402e99e..a8c370897c9f4 100644 --- a/lib/zlib_deflate/defutil.h +++ b/lib/zlib_deflate/defutil.h @@ -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. */ -- 2.39.5