gzip: code shrink

function                                             old     new   delta
fill_window_if_needed                                  -     238    +238
deflate                                              924     907     -17
pack_gzip                                            809     790     -19
fill_window                                          216       -    -216
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 0/2 up/down: 238/-252)          Total: -14 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/archival/gzip.c b/archival/gzip.c
index 10eda7aa3cfa721e7d6011b96951bf74f2a3a3e0..8ef66390a5c65f6faf3b8e0c8deb3c9e0b2dc7bd 100644 (file)
--- a/archival/gzip.c
+++ b/archival/gzip.c
@@ -312,25 +312,24 @@ struct globals {
 #define nice_match      (G1.nice_match)
 #endif
 
-       lng block_start;
-
 /* window position at the beginning of the current output block. Gets
  * negative when the window is moved backwards.
  */
+       lng block_start;
+
        unsigned ins_h; /* hash index of string to be inserted */
 
-#define H_SHIFT  ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
 /* Number of bits by which ins_h and del_h must be shifted at each
  * input step. It must be such that after MIN_MATCH steps, the oldest
  * byte no longer takes part in the hash key, that is:
  * H_SHIFT * MIN_MATCH >= HASH_BITS
  */
-
-       unsigned prev_length;
+#define H_SHIFT  ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
 
 /* Length of the best match at previous step. Matches not greater than this
  * are discarded. This is used in the lazy match evaluation.
  */
+       unsigned prev_length;
 
        unsigned strstart;      /* start of string to insert */
        unsigned match_start;   /* start of matching string */
@@ -347,18 +346,17 @@ struct globals {
        unsigned insize;        /* valid bytes in l_buf */
 #endif
        unsigned outcnt;        /* bytes in output buffer */
-
        smallint eofile;        /* flag set at end of input file */
 
 /* ===========================================================================
  * Local data used by the "bit string" routines.
  */
 
-       unsigned short bi_buf;
-
 /* Output buffer. bits are inserted starting at the bottom (least significant
  * bits).
  */
+       unsigned short bi_buf;
+
 #undef BUF_SIZE
 #define BUF_SIZE (8 * sizeof(G1.bi_buf))
 
@@ -368,7 +366,7 @@ struct globals {
        int bi_valid;
 
 #ifdef DEBUG
-       ulg bits_sent;                  /* bit length of the compressed data */
+       ulg bits_sent;  /* bit length of the compressed data */
 #endif
 
        /*uint32_t *crc_32_tab;*/
@@ -662,6 +660,12 @@ static void fill_window(void)
                }
        }
 }
+/* Both users fill window with the same loop: */
+static void fill_window_if_needed(void)
+{
+       while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
+               fill_window();
+}
 
 
 /* ===========================================================================
@@ -1894,8 +1898,7 @@ static NOINLINE ulg deflate(void)
                 * for the next match, plus MIN_MATCH bytes to insert the
                 * string following the next match.
                 */
-               while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
-                       fill_window();
+               fill_window_if_needed();
        }
        if (match_available)
                ct_tally(0, G1.window[G1.strstart - 1]);
@@ -1948,8 +1951,7 @@ static void lm_init(ush * flagsp)
        /* Make sure that we always have enough lookahead. This is important
         * if input comes from a device such as a tty.
         */
-       while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
-               fill_window();
+       fill_window_if_needed();
 
        //G1.ins_h = 0; // globals are zeroed in pack_gzip()
        for (j = 0; j < MIN_MATCH - 1; j++)