Add comment about not using windowBits of 8 for deflate().

[zlib.git] / inffast.c

diff --git a/inffast.c b/inffast.c
index 97f9a842a006d8331146dfba2962d7603e10beed..bda59ceb6a12b2d7de80ef3c1e7318e54fc979ac 100644 (file)
--- a/inffast.c
+++ b/inffast.c
@@ -1,5 +1,5 @@
 /* inffast.c -- fast decoding
- * Copyright (C) 1995-2008 Mark Adler
+ * Copyright (C) 1995-2008, 2010, 2013 Mark Adler
  * For conditions of distribution and use, see copyright notice in zlib.h
  */
 
@@ -64,13 +64,13 @@
       requires strm->avail_out >= 258 for each loop to avoid checking for
       output space.
  */
-void inflate_fast(strm, start)
+void ZLIB_INTERNAL inflate_fast(strm, start)
 z_streamp strm;
 unsigned start;         /* inflate()'s starting value for strm->avail_out */
 {
     struct inflate_state FAR *state;
-    unsigned char FAR *in;      /* local strm->next_in */
-    unsigned char FAR *last;    /* while in < last, enough input available */
+    z_const unsigned char FAR *in;      /* local strm->next_in */
+    z_const unsigned char FAR *last;    /* have enough input while in < last */
     unsigned char FAR *out;     /* local strm->next_out */
     unsigned char FAR *beg;     /* inflate()'s initial strm->next_out */
     unsigned char FAR *end;     /* while out < end, enough space available */
@@ -79,7 +79,7 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
 #endif
     unsigned wsize;             /* window size or zero if not using window */
     unsigned whave;             /* valid bytes in the window */
-    unsigned write;             /* window write index */
+    unsigned wnext;             /* window write index */
     unsigned char FAR *window;  /* allocated sliding window, if wsize != 0 */
     unsigned long hold;         /* local strm->hold */
     unsigned bits;              /* local strm->bits */
@@ -106,7 +106,7 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
 #endif
     wsize = state->wsize;
     whave = state->whave;
-    write = state->write;
+    wnext = state->wnext;
     window = state->window;
     hold = state->hold;
     bits = state->bits;
@@ -214,7 +214,7 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
 #endif
                     }
                     from = window - OFF;
-                    if (write == 0) {           /* very common case */
+                    if (wnext == 0) {           /* very common case */
                         from += wsize - op;
                         if (op < len) {         /* some from window */
                             len -= op;
@@ -224,17 +224,17 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
                             from = out - dist;  /* rest from output */
                         }
                     }
-                    else if (write < op) {      /* wrap around window */
-                        from += wsize + write - op;
-                        op -= write;
+                    else if (wnext < op) {      /* wrap around window */
+                        from += wsize + wnext - op;
+                        op -= wnext;
                         if (op < len) {         /* some from end of window */
                             len -= op;
                             do {
                                 PUP(out) = PUP(from);
                             } while (--op);
                             from = window - OFF;
-                            if (write < len) {  /* some from start of window */
-                                op = write;
+                            if (wnext < len) {  /* some from start of window */
+                                op = wnext;
                                 len -= op;
                                 do {
                                     PUP(out) = PUP(from);
@@ -244,7 +244,7 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
                         }
                     }
                     else {                      /* contiguous in window */
-                        from += write - op;
+                        from += wnext - op;
                         if (op < len) {         /* some from window */
                             len -= op;
                             do {
@@ -327,7 +327,7 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
    inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe):
    - Using bit fields for code structure
    - Different op definition to avoid & for extra bits (do & for table bits)
-   - Three separate decoding do-loops for direct, window, and write == 0
+   - Three separate decoding do-loops for direct, window, and wnext == 0
    - Special case for distance > 1 copies to do overlapped load and store copy
    - Explicit branch predictions (based on measured branch probabilities)
    - Deferring match copy and interspersed it with decoding subsequent codes