[PATCH] zlib_inflate: Upgrade library code to a recent version

Upgrade the zlib_inflate implementation in the kernel from a patched
version 1.1.3/4 to a patched 1.2.3.

The code in the kernel is about seven years old and I noticed that the
external zlib library's inflate performance was significantly faster (~50%)
than the code in the kernel on ARM (and faster again on x86_32).

For comparison the newer deflate code is 20% slower on ARM and 50% slower
on x86_32 but gives an approx 1% compression ratio improvement.  I don't
consider this to be an improvement for kernel use so have no plans to
change the zlib_deflate code.

Various changes have been made to the zlib code in the kernel, the most
significant being the extra functions/flush option used by ppp_deflate.
This update reimplements the features PPP needs to ensure it continues to
work.

This code has been tested on ARM under both JFFS2 (with zlib compression
enabled) and ppp_deflate and on x86_32.  JFFS2 sees an approx.  10% real
world file read speed improvement.

This patch also removes ZLIB_VERSION as it no longer has a correct value.
We don't need version checks anyway as the kernel's module handling will
take care of that for us.  This removal is also more in keeping with the
zlib author's wishes (http://www.zlib.net/zlib_faq.html#faq24) and I've
added something to the zlib.h header to note its a modified version.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Joern Engel <joern@wh.fh-wedel.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 876 insertions, 210 deletions

diff --git a/lib/zlib_inflate/inflate.c b/lib/zlib_inflate/inflate.c
index 31b9e9054bf7..7f922dccf1a5 100644
--- a/lib/zlib_inflate/inflate.c
+++ b/lib/zlib_inflate/inflate.c
@@ -1,89 +1,148 @@
-/* inflate.c -- zlib interface to inflate modules
- * Copyright (C) 1995-1998 Mark Adler
- * For conditions of distribution and use, see copyright notice in zlib.h 
+/* inflate.c -- zlib decompression
+ * Copyright (C) 1995-2005 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ *
+ * Based on zlib 1.2.3 but modified for the Linux Kernel by
+ * Richard Purdie <richard@openedhand.com>
+ *
+ * Changes mainly for static instead of dynamic memory allocation
+ *
  */
 
 #include <linux/zutil.h>
-#include "infblock.h"
+#include "inftrees.h"
+#include "inflate.h"
+#include "inffast.h"
 #include "infutil.h"
 
 int zlib_inflate_workspacesize(void)
 {
-  return sizeof(struct inflate_workspace);
+    return sizeof(struct inflate_workspace);
 }
 
+int zlib_inflateReset(z_streamp strm)
+{
+    struct inflate_state *state;
+
+    if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
+    state = (struct inflate_state *)strm->state;
+    strm->total_in = strm->total_out = state->total = 0;
+    strm->msg = NULL;
+    strm->adler = 1;        /* to support ill-conceived Java test suite */
+    state->mode = HEAD;
+    state->last = 0;
+    state->havedict = 0;
+    state->dmax = 32768U;
+    state->hold = 0;
+    state->bits = 0;
+    state->lencode = state->distcode = state->next = state->codes;
 
-int zlib_inflateReset(
-        z_streamp z
-)
+    /* Initialise Window */
+    state->wsize = 1U << state->wbits;
+    state->write = 0;
+    state->whave = 0;
+
+    return Z_OK;
+}
+
+#if 0
+int zlib_inflatePrime(z_streamp strm, int bits, int value)
 {
-  if (z == NULL || z->state == NULL || z->workspace == NULL)
-    return Z_STREAM_ERROR;
-  z->total_in = z->total_out = 0;
-  z->msg = NULL;
-  z->state->mode = z->state->nowrap ? BLOCKS : METHOD;
-  zlib_inflate_blocks_reset(z->state->blocks, z, NULL);
-  return Z_OK;
+    struct inflate_state *state;
+
+    if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
+    state = (struct inflate_state *)strm->state;
+    if (bits > 16 || state->bits + bits > 32) return Z_STREAM_ERROR;
+    value &= (1L << bits) - 1;
+    state->hold += value << state->bits;
+    state->bits += bits;
+    return Z_OK;
 }
+#endif
+
+int zlib_inflateInit2(z_streamp strm, int windowBits)
+{
+    struct inflate_state *state;
+
+    if (strm == NULL) return Z_STREAM_ERROR;
+    strm->msg = NULL;                 /* in case we return an error */
+
+    state = &WS(strm)->inflate_state;
+    strm->state = (struct internal_state *)state;
+
+    if (windowBits < 0) {
+        state->wrap = 0;
+        windowBits = -windowBits;
+    }
+    else {
+        state->wrap = (windowBits >> 4) + 1;
+    }
+    if (windowBits < 8 || windowBits > 15) {
+        return Z_STREAM_ERROR;
+    }
+    state->wbits = (unsigned)windowBits;
+    state->window = &WS(strm)->working_window[0];
 
+    return zlib_inflateReset(strm);
+}
 
-int zlib_inflateEnd(
-        z_streamp z
-)
+/*
+   Return state with length and distance decoding tables and index sizes set to
+   fixed code decoding.  This returns fixed tables from inffixed.h.
+ */
+static void zlib_fixedtables(struct inflate_state *state)
 {
-  if (z == NULL || z->state == NULL || z->workspace == NULL)
-    return Z_STREAM_ERROR;
-  if (z->state->blocks != NULL)
-    zlib_inflate_blocks_free(z->state->blocks, z);
-  z->state = NULL;
-  return Z_OK;
+#   include "inffixed.h"
+    state->lencode = lenfix;
+    state->lenbits = 9;
+    state->distcode = distfix;
+    state->distbits = 5;
 }
 
 
-int zlib_inflateInit2_(
-        z_streamp z,
-        int w,
-        const char *version,
-        int stream_size
-)
+/*
+   Update the window with the last wsize (normally 32K) bytes written before
+   returning. This is only called when a window is already in use, or when
+   output has been written during this inflate call, but the end of the deflate
+   stream has not been reached yet. It is also called to window dictionary data
+   when a dictionary is loaded.
+
+   Providing output buffers larger than 32K to inflate() should provide a speed
+   advantage, since only the last 32K of output is copied to the sliding window
+   upon return from inflate(), and since all distances after the first 32K of
+   output will fall in the output data, making match copies simpler and faster.
+   The advantage may be dependent on the size of the processor's data caches.
+ */
+static void zlib_updatewindow(z_streamp strm, unsigned out)
 {
-  if (version == NULL || version[0] != ZLIB_VERSION[0] ||
-      stream_size != sizeof(z_stream) || z->workspace == NULL)
-      return Z_VERSION_ERROR;
-
-  /* initialize state */
-  z->msg = NULL;
-  z->state = &WS(z)->internal_state;
-  z->state->blocks = NULL;
-
-  /* handle undocumented nowrap option (no zlib header or check) */
-  z->state->nowrap = 0;
-  if (w < 0)
-  {
-    w = - w;
-    z->state->nowrap = 1;
-  }
-
-  /* set window size */
-  if (w < 8 || w > 15)
-  {
-    zlib_inflateEnd(z);
-    return Z_STREAM_ERROR;
-  }
-  z->state->wbits = (uInt)w;
-
-  /* create inflate_blocks state */
-  if ((z->state->blocks =
-      zlib_inflate_blocks_new(z, z->state->nowrap ? NULL : zlib_adler32, (uInt)1 << w))
-      == NULL)
-  {
-    zlib_inflateEnd(z);
-    return Z_MEM_ERROR;
-  }
-
-  /* reset state */
-  zlib_inflateReset(z);
-  return Z_OK;
+    struct inflate_state *state;
+    unsigned copy, dist;
+
+    state = (struct inflate_state *)strm->state;
+
+    /* copy state->wsize or less output bytes into the circular window */
+    copy = out - strm->avail_out;
+    if (copy >= state->wsize) {
+        memcpy(state->window, strm->next_out - state->wsize, state->wsize);
+        state->write = 0;
+        state->whave = state->wsize;
+    }
+    else {
+        dist = state->wsize - state->write;
+        if (dist > copy) dist = copy;
+        memcpy(state->window + state->write, strm->next_out - copy, dist);
+        copy -= dist;
+        if (copy) {
+            memcpy(state->window, strm->next_out - copy, copy);
+            state->write = copy;
+            state->whave = state->wsize;
+        }
+        else {
+            state->write += dist;
+            if (state->write == state->wsize) state->write = 0;
+            if (state->whave < state->wsize) state->whave += dist;
+        }
+    }
 }
 
 
@@ -91,157 +150,764 @@ int zlib_inflateInit2_(
  * At the end of a Deflate-compressed PPP packet, we expect to have seen
  * a `stored' block type value but not the (zero) length bytes.
  */
-static int zlib_inflate_packet_flush(inflate_blocks_statef *s)
+/*
+   Returns true if inflate is currently at the end of a block generated by
+   Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
+   implementation to provide an additional safety check. PPP uses
+   Z_SYNC_FLUSH but removes the length bytes of the resulting empty stored
+   block. When decompressing, PPP checks that at the end of input packet,
+   inflate is waiting for these length bytes.
+ */
+static int zlib_inflateSyncPacket(z_streamp strm)
 {
-    if (s->mode != LENS)
-        return Z_DATA_ERROR;
-    s->mode = TYPE;
+    struct inflate_state *state;
+
+    if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
+    state = (struct inflate_state *)strm->state;
+
+    if (state->mode == STORED && state->bits == 0) {
+        state->mode = TYPE;
+        return Z_OK;
+    }
+    return Z_DATA_ERROR;
+}
+
+/* Macros for inflate(): */
+
+/* check function to use adler32() for zlib or crc32() for gzip */
+#define UPDATE(check, buf, len) zlib_adler32(check, buf, len)
+
+/* Load registers with state in inflate() for speed */
+#define LOAD() \
+    do { \
+        put = strm->next_out; \
+        left = strm->avail_out; \
+        next = strm->next_in; \
+        have = strm->avail_in; \
+        hold = state->hold; \
+        bits = state->bits; \
+    } while (0)
+
+/* Restore state from registers in inflate() */
+#define RESTORE() \
+    do { \
+        strm->next_out = put; \
+        strm->avail_out = left; \
+        strm->next_in = next; \
+        strm->avail_in = have; \
+        state->hold = hold; \
+        state->bits = bits; \
+    } while (0)
+
+/* Clear the input bit accumulator */
+#define INITBITS() \
+    do { \
+        hold = 0; \
+        bits = 0; \
+    } while (0)
+
+/* Get a byte of input into the bit accumulator, or return from inflate()
+   if there is no input available. */
+#define PULLBYTE() \
+    do { \
+        if (have == 0) goto inf_leave; \
+        have--; \
+        hold += (unsigned long)(*next++) << bits; \
+        bits += 8; \
+    } while (0)
+
+/* Assure that there are at least n bits in the bit accumulator.  If there is
+   not enough available input to do that, then return from inflate(). */
+#define NEEDBITS(n) \
+    do { \
+        while (bits < (unsigned)(n)) \
+            PULLBYTE(); \
+    } while (0)
+
+/* Return the low n bits of the bit accumulator (n < 16) */
+#define BITS(n) \
+    ((unsigned)hold & ((1U << (n)) - 1))
+
+/* Remove n bits from the bit accumulator */
+#define DROPBITS(n) \
+    do { \
+        hold >>= (n); \
+        bits -= (unsigned)(n); \
+    } while (0)
+
+/* Remove zero to seven bits as needed to go to a byte boundary */
+#define BYTEBITS() \
+    do { \
+        hold >>= bits & 7; \
+        bits -= bits & 7; \
+    } while (0)
+
+/* Reverse the bytes in a 32-bit value */
+#define REVERSE(q) \
+    ((((q) >> 24) & 0xff) + (((q) >> 8) & 0xff00) + \
+     (((q) & 0xff00) << 8) + (((q) & 0xff) << 24))
+
+/*
+   inflate() uses a state machine to process as much input data and generate as
+   much output data as possible before returning.  The state machine is
+   structured roughly as follows:
+
+    for (;;) switch (state) {
+    ...
+    case STATEn:
+        if (not enough input data or output space to make progress)
+            return;
+        ... make progress ...
+        state = STATEm;
+        break;
+    ...
+    }
+
+   so when inflate() is called again, the same case is attempted again, and
+   if the appropriate resources are provided, the machine proceeds to the
+   next state.  The NEEDBITS() macro is usually the way the state evaluates
+   whether it can proceed or should return.  NEEDBITS() does the return if
+   the requested bits are not available.  The typical use of the BITS macros
+   is:
+
+        NEEDBITS(n);
+        ... do something with BITS(n) ...
+        DROPBITS(n);
+
+   where NEEDBITS(n) either returns from inflate() if there isn't enough
+   input left to load n bits into the accumulator, or it continues.  BITS(n)
+   gives the low n bits in the accumulator.  When done, DROPBITS(n) drops
+   the low n bits off the accumulator.  INITBITS() clears the accumulator
+   and sets the number of available bits to zero.  BYTEBITS() discards just
+   enough bits to put the accumulator on a byte boundary.  After BYTEBITS()
+   and a NEEDBITS(8), then BITS(8) would return the next byte in the stream.
+
+   NEEDBITS(n) uses PULLBYTE() to get an available byte of input, or to return
+   if there is no input available.  The decoding of variable length codes uses
+   PULLBYTE() directly in order to pull just enough bytes to decode the next
+   code, and no more.
+
+   Some states loop until they get enough input, making sure that enough
+   state information is maintained to continue the loop where it left off
+   if NEEDBITS() returns in the loop.  For example, want, need, and keep
+   would all have to actually be part of the saved state in case NEEDBITS()
+   returns:
+
+    case STATEw:
+        while (want < need) {
+            NEEDBITS(n);
+            keep[want++] = BITS(n);
+            DROPBITS(n);
+        }
+        state = STATEx;
+    case STATEx:
+
+   As shown above, if the next state is also the next case, then the break
+   is omitted.
+
+   A state may also return if there is not enough output space available to
+   complete that state.  Those states are copying stored data, writing a
+   literal byte, and copying a matching string.
+
+   When returning, a "goto inf_leave" is used to update the total counters,
+   update the check value, and determine whether any progress has been made
+   during that inflate() call in order to return the proper return code.
+   Progress is defined as a change in either strm->avail_in or strm->avail_out.
+   When there is a window, goto inf_leave will update the window with the last
+   output written.  If a goto inf_leave occurs in the middle of decompression
+   and there is no window currently, goto inf_leave will create one and copy
+   output to the window for the next call of inflate().
+
+   In this implementation, the flush parameter of inflate() only affects the
+   return code (per zlib.h).  inflate() always writes as much as possible to
+   strm->next_out, given the space available and the provided input--the effect
+   documented in zlib.h of Z_SYNC_FLUSH.  Furthermore, inflate() always defers
+   the allocation of and copying into a sliding window until necessary, which
+   provides the effect documented in zlib.h for Z_FINISH when the entire input
+   stream available.  So the only thing the flush parameter actually does is:
+   when flush is set to Z_FINISH, inflate() cannot return Z_OK.  Instead it
+   will return Z_BUF_ERROR if it has not reached the end of the stream.
+ */
+
+int zlib_inflate(z_streamp strm, int flush)
+{
+    struct inflate_state *state;
+    unsigned char *next;    /* next input */
+    unsigned char *put;     /* next output */
+    unsigned have, left;        /* available input and output */
+    unsigned long hold;         /* bit buffer */
+    unsigned bits;              /* bits in bit buffer */
+    unsigned in, out;           /* save starting available input and output */
+    unsigned copy;              /* number of stored or match bytes to copy */
+    unsigned char *from;    /* where to copy match bytes from */
+    code this;                  /* current decoding table entry */
+    code last;                  /* parent table entry */
+    unsigned len;               /* length to copy for repeats, bits to drop */
+    int ret;                    /* return code */
+    static const unsigned short order[19] = /* permutation of code lengths */
+        {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
+
+    if (strm == NULL || strm->state == NULL || strm->next_out == NULL ||
+        (strm->next_in == NULL && strm->avail_in != 0))
+        return Z_STREAM_ERROR;
+
+    state = (struct inflate_state *)strm->state;
+
+    if (state->mode == TYPE) state->mode = TYPEDO;      /* skip check */
+    LOAD();
+    in = have;
+    out = left;
+    ret = Z_OK;
+    for (;;)
+        switch (state->mode) {
+        case HEAD:
+            if (state->wrap == 0) {
+                state->mode = TYPEDO;
+                break;
+            }
+            NEEDBITS(16);
+            if (
+                ((BITS(8) << 8) + (hold >> 8)) % 31) {
+                strm->msg = (char *)"incorrect header check";
+                state->mode = BAD;
+                break;
+            }
+            if (BITS(4) != Z_DEFLATED) {
+                strm->msg = (char *)"unknown compression method";
+                state->mode = BAD;
+                break;
+            }
+            DROPBITS(4);
+            len = BITS(4) + 8;
+            if (len > state->wbits) {
+                strm->msg = (char *)"invalid window size";
+                state->mode = BAD;
+                break;
+            }
+            state->dmax = 1U << len;
+            strm->adler = state->check = zlib_adler32(0L, NULL, 0);
+            state->mode = hold & 0x200 ? DICTID : TYPE;
+            INITBITS();
+            break;
+        case DICTID:
+            NEEDBITS(32);
+            strm->adler = state->check = REVERSE(hold);
+            INITBITS();
+            state->mode = DICT;
+        case DICT:
+            if (state->havedict == 0) {
+                RESTORE();
+                return Z_NEED_DICT;
+            }
+            strm->adler = state->check = zlib_adler32(0L, NULL, 0);
+            state->mode = TYPE;
+        case TYPE:
+            if (flush == Z_BLOCK) goto inf_leave;
+        case TYPEDO:
+            if (state->last) {
+                BYTEBITS();
+                state->mode = CHECK;
+                break;
+            }
+            NEEDBITS(3);
+            state->last = BITS(1);
+            DROPBITS(1);
+            switch (BITS(2)) {
+            case 0:                             /* stored block */
+                state->mode = STORED;
+                break;
+            case 1:                             /* fixed block */
+                zlib_fixedtables(state);
+                state->mode = LEN;              /* decode codes */
+                break;
+            case 2:                             /* dynamic block */
+                state->mode = TABLE;
+                break;
+            case 3:
+                strm->msg = (char *)"invalid block type";
+                state->mode = BAD;
+            }
+            DROPBITS(2);
+            break;
+        case STORED:
+            BYTEBITS();                         /* go to byte boundary */
+            NEEDBITS(32);
+            if ((hold & 0xffff) != ((hold >> 16) ^ 0xffff)) {
+                strm->msg = (char *)"invalid stored block lengths";
+                state->mode = BAD;
+                break;
+            }
+            state->length = (unsigned)hold & 0xffff;
+            INITBITS();
+            state->mode = COPY;
+        case COPY:
+            copy = state->length;
+            if (copy) {
+                if (copy > have) copy = have;
+                if (copy > left) copy = left;
+                if (copy == 0) goto inf_leave;
+                memcpy(put, next, copy);
+                have -= copy;
+                next += copy;
+                left -= copy;
+                put += copy;
+                state->length -= copy;
+                break;
+            }
+            state->mode = TYPE;
+            break;
+        case TABLE:
+            NEEDBITS(14);
+            state->nlen = BITS(5) + 257;
+            DROPBITS(5);
+            state->ndist = BITS(5) + 1;
+            DROPBITS(5);
+            state->ncode = BITS(4) + 4;
+            DROPBITS(4);
+#ifndef PKZIP_BUG_WORKAROUND
+            if (state->nlen > 286 || state->ndist > 30) {
+                strm->msg = (char *)"too many length or distance symbols";
+                state->mode = BAD;
+                break;
+            }
+#endif
+            state->have = 0;
+            state->mode = LENLENS;
+        case LENLENS:
+            while (state->have < state->ncode) {
+                NEEDBITS(3);
+                state->lens[order[state->have++]] = (unsigned short)BITS(3);
+                DROPBITS(3);
+            }
+            while (state->have < 19)
+                state->lens[order[state->have++]] = 0;
+            state->next = state->codes;
+            state->lencode = (code const *)(state->next);
+            state->lenbits = 7;
+            ret = zlib_inflate_table(CODES, state->lens, 19, &(state->next),
+                                &(state->lenbits), state->work);
+            if (ret) {
+                strm->msg = (char *)"invalid code lengths set";
+                state->mode = BAD;
+                break;
+            }
+            state->have = 0;
+            state->mode = CODELENS;
+        case CODELENS:
+            while (state->have < state->nlen + state->ndist) {
+                for (;;) {
+                    this = state->lencode[BITS(state->lenbits)];
+                    if ((unsigned)(this.bits) <= bits) break;
+                    PULLBYTE();
+                }
+                if (this.val < 16) {
+                    NEEDBITS(this.bits);
+                    DROPBITS(this.bits);
+                    state->lens[state->have++] = this.val;
+                }
+                else {
+                    if (this.val == 16) {
+                        NEEDBITS(this.bits + 2);
+                        DROPBITS(this.bits);
+                        if (state->have == 0) {
+                            strm->msg = (char *)"invalid bit length repeat";
+                            state->mode = BAD;
+                            break;
+                        }
+                        len = state->lens[state->have - 1];
+                        copy = 3 + BITS(2);
+                        DROPBITS(2);
+                    }
+                    else if (this.val == 17) {
+                        NEEDBITS(this.bits + 3);
+                        DROPBITS(this.bits);
+                        len = 0;
+                        copy = 3 + BITS(3);
+                        DROPBITS(3);
+                    }
+                    else {
+                        NEEDBITS(this.bits + 7);
+                        DROPBITS(this.bits);
+                        len = 0;
+                        copy = 11 + BITS(7);
+                        DROPBITS(7);
+                    }
+                    if (state->have + copy > state->nlen + state->ndist) {
+                        strm->msg = (char *)"invalid bit length repeat";
+                        state->mode = BAD;
+                        break;
+                    }
+                    while (copy--)
+                        state->lens[state->have++] = (unsigned short)len;
+                }
+            }
+
+            /* handle error breaks in while */
+            if (state->mode == BAD) break;
+
+            /* build code tables */
+            state->next = state->codes;
+            state->lencode = (code const *)(state->next);
+            state->lenbits = 9;
+            ret = zlib_inflate_table(LENS, state->lens, state->nlen, &(state->next),
+                                &(state->lenbits), state->work);
+            if (ret) {
+                strm->msg = (char *)"invalid literal/lengths set";
+                state->mode = BAD;
+                break;
+            }
+            state->distcode = (code const *)(state->next);
+            state->distbits = 6;
+            ret = zlib_inflate_table(DISTS, state->lens + state->nlen, state->ndist,
+                            &(state->next), &(state->distbits), state->work);
+            if (ret) {
+                strm->msg = (char *)"invalid distances set";
+                state->mode = BAD;
+                break;
+            }
+            state->mode = LEN;
+        case LEN:
+            if (have >= 6 && left >= 258) {
+                RESTORE();
+                inflate_fast(strm, out);
+                LOAD();
+                break;
+            }
+            for (;;) {
+                this = state->lencode[BITS(state->lenbits)];
+                if ((unsigned)(this.bits) <= bits) break;
+                PULLBYTE();
+            }
+            if (this.op && (this.op & 0xf0) == 0) {
+                last = this;
+                for (;;) {
+                    this = state->lencode[last.val +
+                            (BITS(last.bits + last.op) >> last.bits)];
+                    if ((unsigned)(last.bits + this.bits) <= bits) break;
+                    PULLBYTE();
+                }
+                DROPBITS(last.bits);
+            }
+            DROPBITS(this.bits);
+            state->length = (unsigned)this.val;
+            if ((int)(this.op) == 0) {
+                state->mode = LIT;
+                break;
+            }
+            if (this.op & 32) {
+                state->mode = TYPE;
+                break;
+            }
+            if (this.op & 64) {
+                strm->msg = (char *)"invalid literal/length code";
+                state->mode = BAD;
+                break;
+            }
+            state->extra = (unsigned)(this.op) & 15;
+            state->mode = LENEXT;
+        case LENEXT:
+            if (state->extra) {
+                NEEDBITS(state->extra);
+                state->length += BITS(state->extra);
+                DROPBITS(state->extra);
+            }
+            state->mode = DIST;
+        case DIST:
+            for (;;) {
+                this = state->distcode[BITS(state->distbits)];
+                if ((unsigned)(this.bits) <= bits) break;
+                PULLBYTE();
+            }
+            if ((this.op & 0xf0) == 0) {
+                last = this;
+                for (;;) {
+                    this = state->distcode[last.val +
+                            (BITS(last.bits + last.op) >> last.bits)];
+                    if ((unsigned)(last.bits + this.bits) <= bits) break;
+                    PULLBYTE();
+                }
+                DROPBITS(last.bits);
+            }
+            DROPBITS(this.bits);
+            if (this.op & 64) {
+                strm->msg = (char *)"invalid distance code";
+                state->mode = BAD;
+                break;
+            }
+            state->offset = (unsigned)this.val;
+            state->extra = (unsigned)(this.op) & 15;
+            state->mode = DISTEXT;
+        case DISTEXT:
+            if (state->extra) {
+                NEEDBITS(state->extra);
+                state->offset += BITS(state->extra);
+                DROPBITS(state->extra);
+            }
+#ifdef INFLATE_STRICT
+            if (state->offset > state->dmax) {
+                strm->msg = (char *)"invalid distance too far back";
+                state->mode = BAD;
+                break;
+            }
+#endif
+            if (state->offset > state->whave + out - left) {
+                strm->msg = (char *)"invalid distance too far back";
+                state->mode = BAD;
+                break;
+            }
+            state->mode = MATCH;
+        case MATCH:
+            if (left == 0) goto inf_leave;
+            copy = out - left;
+            if (state->offset > copy) {         /* copy from window */
+                copy = state->offset - copy;
+                if (copy > state->write) {
+                    copy -= state->write;
+                    from = state->window + (state->wsize - copy);
+                }
+                else
+                    from = state->window + (state->write - copy);
+                if (copy > state->length) copy = state->length;
+            }
+            else {                              /* copy from output */
+                from = put - state->offset;
+                copy = state->length;
+            }
+            if (copy > left) copy = left;
+            left -= copy;
+            state->length -= copy;
+            do {
+                *put++ = *from++;
+            } while (--copy);
+            if (state->length == 0) state->mode = LEN;
+            break;
+        case LIT:
+            if (left == 0) goto inf_leave;
+            *put++ = (unsigned char)(state->length);
+            left--;
+            state->mode = LEN;
+            break;
+        case CHECK:
+            if (state->wrap) {
+                NEEDBITS(32);
+                out -= left;
+                strm->total_out += out;
+                state->total += out;
+                if (out)
+                    strm->adler = state->check =
+                        UPDATE(state->check, put - out, out);
+                out = left;
+                if ((
+                     REVERSE(hold)) != state->check) {
+                    strm->msg = (char *)"incorrect data check";
+                    state->mode = BAD;
+                    break;
+                }
+                INITBITS();
+            }
+            state->mode = DONE;
+        case DONE:
+            ret = Z_STREAM_END;
+            goto inf_leave;
+        case BAD:
+            ret = Z_DATA_ERROR;
+            goto inf_leave;
+        case MEM:
+            return Z_MEM_ERROR;
+        case SYNC:
+        default:
+            return Z_STREAM_ERROR;
+        }
+
+    /*
+       Return from inflate(), updating the total counts and the check value.
+       If there was no progress during the inflate() call, return a buffer
+       error.  Call zlib_updatewindow() to create and/or update the window state.
+     */
+  inf_leave:
+    RESTORE();
+    if (state->wsize || (state->mode < CHECK && out != strm->avail_out))
+        zlib_updatewindow(strm, out);
+
+    in -= strm->avail_in;
+    out -= strm->avail_out;
+    strm->total_in += in;
+    strm->total_out += out;
+    state->total += out;
+    if (state->wrap && out)
+        strm->adler = state->check =
+            UPDATE(state->check, strm->next_out - out, out);
+
+    strm->data_type = state->bits + (state->last ? 64 : 0) +
+                      (state->mode == TYPE ? 128 : 0);
+    if (((in == 0 && out == 0) || flush == Z_FINISH) && ret == Z_OK)
+        ret = Z_BUF_ERROR;
+
+    if (flush == Z_PACKET_FLUSH && ret == Z_OK &&
+            (strm->avail_out != 0 || strm->avail_in == 0))
+                return zlib_inflateSyncPacket(strm);
+    return ret;
+}
+
+int zlib_inflateEnd(z_streamp strm)
+{
+    if (strm == NULL || strm->state == NULL)
+        return Z_STREAM_ERROR;
     return Z_OK;
 }
 
+#if 0
+int zlib_inflateSetDictionary(z_streamp strm, const Byte *dictionary,
+        uInt dictLength)
+{
+    struct inflate_state *state;
+    unsigned long id;
+
+    /* check state */
+    if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
+    state = (struct inflate_state *)strm->state;
+    if (state->wrap != 0 && state->mode != DICT)
+        return Z_STREAM_ERROR;
+
+    /* check for correct dictionary id */
+    if (state->mode == DICT) {
+        id = zlib_adler32(0L, NULL, 0);
+        id = zlib_adler32(id, dictionary, dictLength);
+        if (id != state->check)
+            return Z_DATA_ERROR;
+    }
+
+    /* copy dictionary to window */
+    zlib_updatewindow(strm, strm->avail_out);
 
-int zlib_inflateInit_(
-        z_streamp z,
-        const char *version,
-        int stream_size
-)
+    if (dictLength > state->wsize) {
+        memcpy(state->window, dictionary + dictLength - state->wsize,
+                state->wsize);
+        state->whave = state->wsize;
+    }
+    else {
+        memcpy(state->window + state->wsize - dictLength, dictionary,
+                dictLength);
+        state->whave = dictLength;
+    }
+    state->havedict = 1;
+    return Z_OK;
+}
+#endif
+
+#if 0
+/*
+   Search buf[0..len-1] for the pattern: 0, 0, 0xff, 0xff.  Return when found
+   or when out of input.  When called, *have is the number of pattern bytes
+   found in order so far, in 0..3.  On return *have is updated to the new
+   state.  If on return *have equals four, then the pattern was found and the
+   return value is how many bytes were read including the last byte of the
+   pattern.  If *have is less than four, then the pattern has not been found
+   yet and the return value is len.  In the latter case, zlib_syncsearch() can be
+   called again with more data and the *have state.  *have is initialized to
+   zero for the first call.
+ */
+static unsigned zlib_syncsearch(unsigned *have, unsigned char *buf,
+        unsigned len)
 {
-  return zlib_inflateInit2_(z, DEF_WBITS, version, stream_size);
+    unsigned got;
+    unsigned next;
+
+    got = *have;
+    next = 0;
+    while (next < len && got < 4) {
+        if ((int)(buf[next]) == (got < 2 ? 0 : 0xff))
+            got++;
+        else if (buf[next])
+            got = 0;
+        else
+            got = 4 - got;
+        next++;
+    }
+    *have = got;
+    return next;
 }
+#endif
 
-#undef NEEDBYTE
-#undef NEXTBYTE
-#define NEEDBYTE {if(z->avail_in==0)goto empty;r=trv;}
-#define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++)
+#if 0
+int zlib_inflateSync(z_streamp strm)
+{
+    unsigned len;               /* number of bytes to look at or looked at */
+    unsigned long in, out;      /* temporary to save total_in and total_out */
+    unsigned char buf[4];       /* to restore bit buffer to byte string */
+    struct inflate_state *state;
+
+    /* check parameters */
+    if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
+    state = (struct inflate_state *)strm->state;
+    if (strm->avail_in == 0 && state->bits < 8) return Z_BUF_ERROR;
+
+    /* if first time, start search in bit buffer */
+    if (state->mode != SYNC) {
+        state->mode = SYNC;
+        state->hold <<= state->bits & 7;
+        state->bits -= state->bits & 7;
+        len = 0;
+        while (state->bits >= 8) {
+            buf[len++] = (unsigned char)(state->hold);
+            state->hold >>= 8;
+            state->bits -= 8;
+        }
+        state->have = 0;
+        zlib_syncsearch(&(state->have), buf, len);
+    }
+
+    /* search available input */
+    len = zlib_syncsearch(&(state->have), strm->next_in, strm->avail_in);
+    strm->avail_in -= len;
+    strm->next_in += len;
+    strm->total_in += len;
+
+    /* return no joy or set up to restart inflate() on a new block */
+    if (state->have != 4) return Z_DATA_ERROR;
+    in = strm->total_in;  out = strm->total_out;
+    zlib_inflateReset(strm);
+    strm->total_in = in;  strm->total_out = out;
+    state->mode = TYPE;
+    return Z_OK;
+}
+#endif
 
-int zlib_inflate(
-        z_streamp z,
-        int f
-)
+/*
+ * This subroutine adds the data at next_in/avail_in to the output history
+ * without performing any output.  The output buffer must be "caught up";
+ * i.e. no pending output but this should always be the case. The state must
+ * be waiting on the start of a block (i.e. mode == TYPE or HEAD).  On exit,
+ * the output will also be caught up, and the checksum will have been updated
+ * if need be.
+ */
+int zlib_inflateIncomp(z_stream *z)
 {
-  int r, trv;
-  uInt b;
-
-  if (z == NULL || z->state == NULL || z->next_in == NULL)
-    return Z_STREAM_ERROR;
-  trv = f == Z_FINISH ? Z_BUF_ERROR : Z_OK;
-  r = Z_BUF_ERROR;
-  while (1) switch (z->state->mode)
-  {
-    case METHOD:
-      NEEDBYTE
-      if (((z->state->sub.method = NEXTBYTE) & 0xf) != Z_DEFLATED)
-      {
-        z->state->mode = I_BAD;
-        z->msg = (char*)"unknown compression method";
-        z->state->sub.marker = 5;       /* can't try inflateSync */
-        break;
-      }
-      if ((z->state->sub.method >> 4) + 8 > z->state->wbits)
-      {
-        z->state->mode = I_BAD;
-        z->msg = (char*)"invalid window size";
-        z->state->sub.marker = 5;       /* can't try inflateSync */
-        break;
-      }
-      z->state->mode = FLAG;
-    case FLAG:
-      NEEDBYTE
-      b = NEXTBYTE;
-      if (((z->state->sub.method << 8) + b) % 31)
-      {
-        z->state->mode = I_BAD;
-        z->msg = (char*)"incorrect header check";
-        z->state->sub.marker = 5;       /* can't try inflateSync */
-        break;
-      }
-      if (!(b & PRESET_DICT))
-      {
-        z->state->mode = BLOCKS;
-        break;
-      }
-      z->state->mode = DICT4;
-    case DICT4:
-      NEEDBYTE
-      z->state->sub.check.need = (uLong)NEXTBYTE << 24;
-      z->state->mode = DICT3;
-    case DICT3:
-      NEEDBYTE
-      z->state->sub.check.need += (uLong)NEXTBYTE << 16;
-      z->state->mode = DICT2;
-    case DICT2:
-      NEEDBYTE
-      z->state->sub.check.need += (uLong)NEXTBYTE << 8;
-      z->state->mode = DICT1;
-    case DICT1:
-      NEEDBYTE
-      z->state->sub.check.need += (uLong)NEXTBYTE;
-      z->adler = z->state->sub.check.need;
-      z->state->mode = DICT0;
-      return Z_NEED_DICT;
-    case DICT0:
-      z->state->mode = I_BAD;
-      z->msg = (char*)"need dictionary";
-      z->state->sub.marker = 0;       /* can try inflateSync */
-      return Z_STREAM_ERROR;
-    case BLOCKS:
-      r = zlib_inflate_blocks(z->state->blocks, z, r);
-      if (f == Z_PACKET_FLUSH && z->avail_in == 0 && z->avail_out != 0)
-          r = zlib_inflate_packet_flush(z->state->blocks);
-      if (r == Z_DATA_ERROR)
-      {
-        z->state->mode = I_BAD;
-        z->state->sub.marker = 0;       /* can try inflateSync */
-        break;
-      }
-      if (r == Z_OK)
-        r = trv;
-      if (r != Z_STREAM_END)
-        return r;
-      r = trv;
-      zlib_inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was);
-      if (z->state->nowrap)
-      {
-        z->state->mode = I_DONE;
-        break;
-      }
-      z->state->mode = CHECK4;
-    case CHECK4:
-      NEEDBYTE
-      z->state->sub.check.need = (uLong)NEXTBYTE << 24;
-      z->state->mode = CHECK3;
-    case CHECK3:
-      NEEDBYTE
-      z->state->sub.check.need += (uLong)NEXTBYTE << 16;
-      z->state->mode = CHECK2;
-    case CHECK2:
-      NEEDBYTE
-      z->state->sub.check.need += (uLong)NEXTBYTE << 8;
-      z->state->mode = CHECK1;
-    case CHECK1:
-      NEEDBYTE
-      z->state->sub.check.need += (uLong)NEXTBYTE;
-
-      if (z->state->sub.check.was != z->state->sub.check.need)
-      {
-        z->state->mode = I_BAD;
-        z->msg = (char*)"incorrect data check";
-        z->state->sub.marker = 5;       /* can't try inflateSync */
-        break;
-      }
-      z->state->mode = I_DONE;
-    case I_DONE:
-      return Z_STREAM_END;
-    case I_BAD:
-      return Z_DATA_ERROR;
-    default:
-      return Z_STREAM_ERROR;
-  }
- empty:
-  if (f != Z_PACKET_FLUSH)
-    return r;
-  z->state->mode = I_BAD;
-  z->msg = (char *)"need more for packet flush";
-  z->state->sub.marker = 0;       /* can try inflateSync */
-  return Z_DATA_ERROR;
+    struct inflate_state *state = (struct inflate_state *)z->state;
+    Byte *saved_no = z->next_out;
+    uInt saved_ao = z->avail_out;
+
+    if (state->mode != TYPE && state->mode != HEAD)
+        return Z_DATA_ERROR;
+
+    /* Setup some variables to allow misuse of updateWindow */
+    z->avail_out = 0;
+    z->next_out = z->next_in + z->avail_in;
+
+    zlib_updatewindow(z, z->avail_in);
+
+    /* Restore saved variables */
+    z->avail_out = saved_ao;
+    z->next_out = saved_no;
+
+    z->adler = state->check =
+        UPDATE(state->check, z->next_in, z->avail_in);
+
+    z->total_out += z->avail_in;
+    z->total_in += z->avail_in;
+    z->next_in += z->avail_in;
+    state->total += z->avail_in;
+    z->avail_in = 0;
+
+    return Z_OK;
 }