X-Git-Url: http://git.indexdata.com/?a=blobdiff_plain;f=isamb%2Fisamb.c;h=77114239f2788119545f408d864964f48b1636be;hb=1afbdd9135e38942201f0ad0eaae5b6903755aeb;hp=5627af468ec48f97401ebf6b66a2d9a126d06e01;hpb=3e72747f4b28856e5f684dbe8984f8fb28680e62;p=idzebra-moved-to-github.git

diff --git a/isamb/isamb.c b/isamb/isamb.c
index 5627af4..7711423 100644
--- a/isamb/isamb.c
+++ b/isamb/isamb.c
@@ -1,154 +1,407 @@
-/*
- *  Copyright (c) 2000-2002, Index Data.
- *  See the file LICENSE for details.
- *
- *  $Id: isamb.c,v 1.10 2002-04-26 08:44:47 adam Exp $
- */
+/* $Id: isamb.c,v 1.39 2004-06-02 18:50:37 heikki Exp $
+   Copyright (C) 1995,1996,1997,1998,1999,2000,2001,2002,2003,2004
+   Index Data Aps
+
+This file is part of the Zebra server.
+
+Zebra is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 2, or (at your option) any later
+version.
+
+Zebra is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with Zebra; see the file LICENSE.zebra.  If not, write to the
+Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+02111-1307, USA.
+*/
+
+#include <string.h>
 #include <yaz/xmalloc.h>
 #include <yaz/log.h>
 #include <isamb.h>
 #include <assert.h>
 
+#ifndef ISAMB_DEBUG
+#define ISAMB_DEBUG 0
+#endif
+
 struct ISAMB_head {
     int first_block;
     int last_block;
     int block_size;
     int block_max;
+    int free_list;
 };
 
 #define ISAMB_DATA_OFFSET 3
 
+/* maximum size of encoded buffer */
 #define DST_ITEM_MAX 256
 
-/* approx 2*4 K + max size of item */
-#define DST_BUF_SIZE 8448
+#define ISAMB_MAX_LEVEL 10
+/* approx 2*max page + max size of item */
+#define DST_BUF_SIZE 16840
+
+#define ISAMB_CACHE_ENTRY_SIZE 4096
+
+/* CAT_MAX: _must_ be power of 2 */
+#define CAT_MAX 4
+#define CAT_MASK (CAT_MAX-1)
+/* CAT_NO: <= CAT_MAX */
+#define CAT_NO 4
 
+/* ISAMB_PTR_CODEC=1 var, =0 fixed */
+#define ISAMB_PTR_CODEC  1
+
+struct ISAMB_cache_entry {
+    ISAMB_P pos;
+    unsigned char *buf;
+    int dirty;
+    int hits;
+    struct ISAMB_cache_entry *next;
+};
 
 struct ISAMB_file {
     BFile bf;
     int head_dirty;
     struct ISAMB_head head;
+    struct ISAMB_cache_entry *cache_entries;
 };
 
 struct ISAMB_s {
     BFiles bfs;
-    ISAMC_M method;
+    ISAMC_M *method;
 
     struct ISAMB_file *file;
     int no_cat;
+    int cache; /* 0=no cache, 1=use cache, -1=dummy isam (for testing only) */
+    int log_io;        /* log level for bf_read/bf_write calls */
+    int log_freelist;  /* log level for freelist handling */
+    int skipped_numbers; /* on a leaf node */
+    int returned_numbers; 
+    int skipped_nodes[ISAMB_MAX_LEVEL]; /* [0]=skipped leaves, 1=higher etc */
+    int accessed_nodes[ISAMB_MAX_LEVEL]; /* nodes we did not skip */
 };
 
 struct ISAMB_block {
-    int pos;
+    ISAMB_P pos;
     int cat;
     int size;
     int leaf;
     int dirty;
+    int deleted;
     int offset;
     char *bytes;
     unsigned char *buf;
     void *decodeClientData;
+    int log_rw;
 };
 
 struct ISAMB_PP_s {
     ISAMB isamb;
+    ISAMB_P pos;
     int level;
+    int maxlevel; /* total depth */
+    int total_size;
+    int no_blocks;
+    int skipped_numbers; /* on a leaf node */
+    int returned_numbers; 
+    int skipped_nodes[ISAMB_MAX_LEVEL]; /* [0]=skipped leaves, 1=higher etc */
+    int accessed_nodes[ISAMB_MAX_LEVEL]; /* nodes we did not skip */
     struct ISAMB_block **block;
 };
 
-void encode_ptr (char **dst, int pos)
+#if ISAMB_PTR_CODEC
+static void encode_ptr (char **dst, unsigned pos)
 {
-    memcpy (*dst, &pos, sizeof(pos));
+    unsigned char *bp = (unsigned char*) *dst;
+
+    while (pos > 127)
+    {
+         *bp++ = 128 | (pos & 127);
+         pos = pos >> 7;
+    }
+    *bp++ = pos;
+    *dst = (char *) bp;
+}
+#else
+static void encode_ptr (char **dst, unsigned pos)
+{
+    memcpy(*dst, &pos, sizeof(pos));
     (*dst) += sizeof(pos);
 }
+#endif
 
-void decode_ptr (char **src, int *pos)
+#if ISAMB_PTR_CODEC
+static void decode_ptr (char **src1, int *pos)
+{
+    unsigned char **src = (unsigned char **) src1;
+    unsigned d = 0;
+    unsigned char c;
+    unsigned r = 0;
+
+    while (((c = *(*src)++) & 128))
+    {
+        d += ((c & 127) << r);
+	r += 7;
+    }
+    d += (c << r);
+    *pos = d;
+}
+#else
+static void decode_ptr (char **src, int *pos)
 {
-    memcpy (pos, *src, sizeof(*pos));
-    (*src) += sizeof(*pos);
+     memcpy (pos, *src, sizeof(*pos));
+     (*src) += sizeof(*pos);
 }
+#endif
 
-ISAMB isamb_open (BFiles bfs, const char *name, int writeflag, ISAMC_M method)
+ISAMB isamb_open (BFiles bfs, const char *name, int writeflag, ISAMC_M *method,
+                  int cache)
 {
     ISAMB isamb = xmalloc (sizeof(*isamb));
-    int i, b_size = 64;
+    int i, b_size = 32;
 
     isamb->bfs = bfs;
-    isamb->method = (ISAMC_M) xmalloc (sizeof(*method));
+    isamb->method = (ISAMC_M *) xmalloc (sizeof(*method));
     memcpy (isamb->method, method, sizeof(*method));
-    isamb->no_cat = 4;
+    isamb->no_cat = CAT_NO;
+    isamb->log_io = 0;
+    isamb->log_freelist = 0;
+    isamb->cache = cache;
+    isamb->skipped_numbers=0;
+    isamb->returned_numbers=0;
+    for (i=0;i<ISAMB_MAX_LEVEL;i++)
+      isamb->skipped_nodes[i]= isamb->accessed_nodes[i]=0;
 
+    assert (cache == 0);
     isamb->file = xmalloc (sizeof(*isamb->file) * isamb->no_cat);
     for (i = 0; i<isamb->no_cat; i++)
     {
         char fname[DST_BUF_SIZE];
-        isamb->file[i].head.first_block = 1;
-        isamb->file[i].head.last_block = 1;
-        isamb->file[i].head.block_size = b_size;
-        isamb->file[i].head.block_max = b_size - ISAMB_DATA_OFFSET;
-        b_size = b_size * 4;
+        isamb->file[i].cache_entries = 0;
         isamb->file[i].head_dirty = 0;
-        sprintf (fname, "%s-%d", name, i);
-        isamb->file[i].bf =
-            bf_open (bfs, fname, isamb->file[i].head.block_size, writeflag);
-    
-        bf_read (isamb->file[i].bf, 0, 0, sizeof(struct ISAMB_head),
-                 &isamb->file[i].head);
+        sprintf (fname, "%s%c", name, i+'A');
+        if (cache)
+            isamb->file[i].bf = bf_open (bfs, fname, ISAMB_CACHE_ENTRY_SIZE,
+                                         writeflag);
+        else
+            isamb->file[i].bf = bf_open (bfs, fname, b_size, writeflag);
+
+        
+        if (!bf_read (isamb->file[i].bf, 0, 0, sizeof(struct ISAMB_head),
+                      &isamb->file[i].head))
+	{
+            isamb->file[i].head.first_block = ISAMB_CACHE_ENTRY_SIZE/b_size+1;
+            isamb->file[i].head.last_block = isamb->file[i].head.first_block;
+            isamb->file[i].head.block_size = b_size;
+            isamb->file[i].head.block_max = b_size - ISAMB_DATA_OFFSET;
+            isamb->file[i].head.free_list = 0;
+	}
+        assert (isamb->file[i].head.block_size >= ISAMB_DATA_OFFSET);
+        isamb->file[i].head_dirty = 0;
+        assert(isamb->file[i].head.block_size == b_size);
+        b_size = b_size * 4;
     }
+#if ISAMB_DEBUG
+    logf(LOG_WARN, "isamb debug enabled. Things will be slower than usual");
+#endif
     return isamb;
 }
 
+static void flush_blocks (ISAMB b, int cat)
+{
+    while (b->file[cat].cache_entries)
+    {
+        struct ISAMB_cache_entry *ce_this = b->file[cat].cache_entries;
+        b->file[cat].cache_entries = ce_this->next;
+
+        if (ce_this->dirty)
+        {
+            yaz_log (b->log_io, "bf_write: flush_blocks");
+            bf_write (b->file[cat].bf, ce_this->pos, 0, 0, ce_this->buf);
+        }
+        xfree (ce_this->buf);
+        xfree (ce_this);
+    }
+}
+
+static int get_block (ISAMB b, ISAMC_P pos, char *userbuf, int wr)
+{
+    int cat = pos&CAT_MASK;
+    int off = ((pos/CAT_MAX) & 
+               (ISAMB_CACHE_ENTRY_SIZE / b->file[cat].head.block_size - 1))
+        * b->file[cat].head.block_size;
+    int norm = pos / (CAT_MASK*ISAMB_CACHE_ENTRY_SIZE / b->file[cat].head.block_size);
+    int no = 0;
+    struct ISAMB_cache_entry **ce, *ce_this = 0, **ce_last = 0;
+
+    if (!b->cache)
+        return 0;
+
+    assert (ISAMB_CACHE_ENTRY_SIZE >= b->file[cat].head.block_size);
+    for (ce = &b->file[cat].cache_entries; *ce; ce = &(*ce)->next, no++)
+    {
+        ce_last = ce;
+        if ((*ce)->pos == norm)
+        {
+            ce_this = *ce;
+            *ce = (*ce)->next;   /* remove from list */
+            
+            ce_this->next = b->file[cat].cache_entries;  /* move to front */
+            b->file[cat].cache_entries = ce_this;
+            
+            if (wr)
+            {
+                memcpy (ce_this->buf + off, userbuf, 
+                        b->file[cat].head.block_size);
+                ce_this->dirty = 1;
+            }
+            else
+                memcpy (userbuf, ce_this->buf + off,
+                        b->file[cat].head.block_size);
+            return 1;
+        }
+    }
+    if (no >= 40)
+    {
+        assert (no == 40);
+        assert (ce_last && *ce_last);
+        ce_this = *ce_last;
+        *ce_last = 0;  /* remove the last entry from list */
+        if (ce_this->dirty)
+        {
+            yaz_log (b->log_io, "bf_write: get_block");
+            bf_write (b->file[cat].bf, ce_this->pos, 0, 0, ce_this->buf);
+        }
+        xfree (ce_this->buf);
+        xfree (ce_this);
+    }
+    ce_this = xmalloc (sizeof(*ce_this));
+    ce_this->next = b->file[cat].cache_entries;
+    b->file[cat].cache_entries = ce_this;
+    ce_this->buf = xmalloc (ISAMB_CACHE_ENTRY_SIZE);
+    ce_this->pos = norm;
+    yaz_log (b->log_io, "bf_read: get_block");
+    if (!bf_read (b->file[cat].bf, norm, 0, 0, ce_this->buf))
+        memset (ce_this->buf, 0, ISAMB_CACHE_ENTRY_SIZE);
+    if (wr)
+    {
+        memcpy (ce_this->buf + off, userbuf, b->file[cat].head.block_size);
+        ce_this->dirty = 1;
+    }
+    else
+    {
+        ce_this->dirty = 0;
+        memcpy (userbuf, ce_this->buf + off, b->file[cat].head.block_size);
+    }
+    return 1;
+}
+
+
 void isamb_close (ISAMB isamb)
 {
     int i;
+    for (i=0;isamb->accessed_nodes[i];i++)
+        logf(LOG_DEBUG,"isamb_close  level leaf-%d: %d read, %d skipped",
+             i, isamb->accessed_nodes[i], isamb->skipped_nodes[i]);
+    logf(LOG_DEBUG,"isamb_close returned %d values, skipped %d",
+         isamb->skipped_numbers, isamb->returned_numbers);
     for (i = 0; i<isamb->no_cat; i++)
     {
+        flush_blocks (isamb, i);
         if (isamb->file[i].head_dirty)
             bf_write (isamb->file[i].bf, 0, 0,
                       sizeof(struct ISAMB_head), &isamb->file[i].head);
+        
+        bf_close (isamb->file[i].bf);
     }
     xfree (isamb->file);
     xfree (isamb->method);
     xfree (isamb);
 }
 
-struct ISAMB_block *open_block (ISAMB b, ISAMC_P pos)
+static struct ISAMB_block *open_block (ISAMB b, ISAMC_P pos)
 {
-    int cat = pos&3;
+    int cat = pos&CAT_MASK;
     struct ISAMB_block *p;
     if (!pos)
         return 0;
     p = xmalloc (sizeof(*p));
     p->pos = pos;
-    p->cat = pos & 3;
+    p->cat = pos & CAT_MASK;
     p->buf = xmalloc (b->file[cat].head.block_size);
-    bf_read (b->file[cat].bf, pos/4, 0, 0, p->buf);
+
+    if (!get_block (b, pos, p->buf, 0))
+    {
+        yaz_log (b->log_io, "bf_read: open_block");
+        if (!bf_read (b->file[cat].bf, pos/CAT_MAX, 0, 0, p->buf))
+        {
+            yaz_log (LOG_FATAL, "isamb: read fail for pos=%ld block=%ld",
+                     (long) pos, (long) pos/CAT_MAX);
+            abort();
+        }
+    }
     p->bytes = p->buf + ISAMB_DATA_OFFSET;
     p->leaf = p->buf[0];
-    p->size = p->buf[1] + 256 * p->buf[2] - ISAMB_DATA_OFFSET;
+    p->size = (p->buf[1] + 256 * p->buf[2]) - ISAMB_DATA_OFFSET;
+    if (p->size < 0)
+    {
+        yaz_log (LOG_FATAL, "Bad block size %d in pos=%d\n", p->size, pos);
+    }
+    assert (p->size >= 0);
     p->offset = 0;
     p->dirty = 0;
+    p->deleted = 0;
     p->decodeClientData = (*b->method->code_start)(ISAMC_DECODE);
+    yaz_log (LOG_DEBUG, "isamb_open_block: Opened block %d ofs=%d",pos, p->offset);
     return p;
 }
 
 struct ISAMB_block *new_block (ISAMB b, int leaf, int cat)
 {
     struct ISAMB_block *p;
-    int block_no;
-    
+
     p = xmalloc (sizeof(*p));
-    block_no = b->file[cat].head.last_block++;
-    p->cat = cat;
-    p->pos = block_no * 4 + cat;
+    p->buf = xmalloc (b->file[cat].head.block_size);
+
+    if (!b->file[cat].head.free_list)
+    {
+        int block_no;
+        block_no = b->file[cat].head.last_block++;
+        p->pos = block_no * CAT_MAX + cat;
+    }
+    else
+    {
+        p->pos = b->file[cat].head.free_list;
+        assert((p->pos & CAT_MASK) == cat);
+        if (!get_block (b, p->pos, p->buf, 0))
+        {
+            yaz_log (b->log_io, "bf_read: new_block");
+            if (!bf_read (b->file[cat].bf, p->pos/CAT_MAX, 0, 0, p->buf))
+            {
+                yaz_log (LOG_FATAL, "isamb: read fail for pos=%ld block=%ld",
+                         (long) p->pos/CAT_MAX, (long) p->pos/CAT_MAX);
+                abort ();
+            }
+        }
+        yaz_log (b->log_freelist, "got block %d from freelist %d:%d", p->pos,
+                 cat, p->pos/CAT_MAX);
+        memcpy (&b->file[cat].head.free_list, p->buf, sizeof(int));
+    }
     p->cat = cat;
     b->file[cat].head_dirty = 1;
-    p->buf = xmalloc (b->file[cat].head.block_size);
     memset (p->buf, 0, b->file[cat].head.block_size);
     p->bytes = p->buf + ISAMB_DATA_OFFSET;
     p->leaf = leaf;
     p->size = 0;
     p->dirty = 1;
+    p->deleted = 0;
     p->offset = 0;
     p->decodeClientData = (*b->method->code_start)(ISAMC_DECODE);
     return p;
@@ -165,17 +418,63 @@ struct ISAMB_block *new_int (ISAMB b, int cat)
     return new_block (b, 0, cat);
 }
 
+static void check_block (ISAMB b, struct ISAMB_block *p)
+{
+    if (p->leaf)
+    {
+        ;
+    }
+    else
+    {
+        /* sanity check */
+        char *startp = p->bytes;
+        char *src = startp;
+        char *endp = p->bytes + p->size;
+        int pos;
+            
+        decode_ptr (&src, &pos);
+        assert ((pos&CAT_MASK) == p->cat);
+        while (src != endp)
+        {
+            int item_len;
+            decode_ptr (&src, &item_len);
+            assert (item_len > 0 && item_len < 30);
+            src += item_len;
+            decode_ptr (&src, &pos);
+            assert ((pos&CAT_MASK) == p->cat);
+        }
+    }
+}
+
 void close_block (ISAMB b, struct ISAMB_block *p)
 {
     if (!p)
         return;
-    if (p->dirty)
+    if (p->deleted)
+    {
+        yaz_log (b->log_freelist, "release block %d from freelist %d:%d",
+                 p->pos, p->cat, p->pos/CAT_MAX);
+        memcpy (p->buf, &b->file[p->cat].head.free_list, sizeof(int));
+        b->file[p->cat].head.free_list = p->pos;
+        if (!get_block (b, p->pos, p->buf, 1))
+        {
+            yaz_log (b->log_io, "bf_write: close_block (deleted)");
+            bf_write (b->file[p->cat].bf, p->pos/CAT_MAX, 0, 0, p->buf);
+        }
+    }
+    else if (p->dirty)
     {
         int size = p->size + ISAMB_DATA_OFFSET;
+        assert (p->size >= 0);
         p->buf[0] = p->leaf;
         p->buf[1] = size & 255;
         p->buf[2] = size >> 8;
-        bf_write (b->file[p->cat].bf, p->pos/4, 0, 0, p->buf);
+        check_block(b, p);
+        if (!get_block (b, p->pos, p->buf, 1))
+        {
+            yaz_log (b->log_io, "bf_write: close_block");
+            bf_write (b->file[p->cat].bf, p->pos/CAT_MAX, 0, 0, p->buf);
+        }
     }
     (*b->method->code_stop)(ISAMC_DECODE, p->decodeClientData);
     xfree (p->buf);
@@ -183,15 +482,16 @@ void close_block (ISAMB b, struct ISAMB_block *p)
 }
 
 int insert_sub (ISAMB b, struct ISAMB_block **p,
-                void *new_item,
-                ISAMC_I stream,
+                void *new_item, int *mode,
+                ISAMC_I *stream,
                 struct ISAMB_block **sp,
                 void *sub_item, int *sub_size,
                 void *max_item);
 
 int insert_int (ISAMB b, struct ISAMB_block *p, void *lookahead_item,
-                ISAMC_I stream, struct ISAMB_block **sp,
-                void *split_item, int *split_size)
+                int *mode,
+                ISAMC_I *stream, struct ISAMB_block **sp,
+                void *split_item, int *split_size, void *last_max_item)
 {
     char *startp = p->bytes;
     char *src = startp;
@@ -204,19 +504,23 @@ int insert_int (ISAMB b, struct ISAMB_block *p, void *lookahead_item,
 
     *sp = 0;
 
+    assert(p->size >= 0);
     decode_ptr (&src, &pos);
     while (src != endp)
     {
         int item_len;
         int d;
+        char *src0 = src;
         decode_ptr (&src, &item_len);
         d = (*b->method->compare_item)(src, lookahead_item);
         if (d > 0)
         {
             sub_p1 = open_block (b, pos);
             assert (sub_p1);
-            more = insert_sub (b, &sub_p1, lookahead_item, stream, &sub_p2, 
+            more = insert_sub (b, &sub_p1, lookahead_item, mode,
+                               stream, &sub_p2, 
                                sub_item, &sub_size, src);
+            src = src0;
             break;
         }
         src += item_len;
@@ -226,8 +530,8 @@ int insert_int (ISAMB b, struct ISAMB_block *p, void *lookahead_item,
     {
         sub_p1 = open_block (b, pos);
         assert (sub_p1);
-        more = insert_sub (b, &sub_p1, lookahead_item, stream, &sub_p2, 
-                           sub_item, &sub_size, 0);
+        more = insert_sub (b, &sub_p1, lookahead_item, mode, stream, &sub_p2, 
+                           sub_item, &sub_size, last_max_item);
     }
     if (sub_p2)
     {
@@ -253,6 +557,7 @@ int insert_int (ISAMB b, struct ISAMB_block *p, void *lookahead_item,
             dst += endp - src;
         }
         p->size = dst - dst_buf;
+        assert (p->size >= 0);
         if (p->size <= b->file[p->cat].head.block_max)
         {
             memcpy (startp, dst_buf, dst - dst_buf);
@@ -294,7 +599,8 @@ int insert_int (ISAMB b, struct ISAMB_block *p, void *lookahead_item,
 
 
 int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
-                 ISAMC_I stream, struct ISAMB_block **sp2,
+                 int *lookahead_mode, ISAMC_I *stream,
+		 struct ISAMB_block **sp2,
                  void *sub_item, int *sub_size,
                  void *max_item)
 {
@@ -305,7 +611,7 @@ int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
     void *c1 = (*b->method->code_start)(ISAMC_DECODE);
     void *c2 = (*b->method->code_start)(ISAMC_ENCODE);
     int more = 1;
-    int quater = b->file[b->no_cat-1].head.block_max / 4;
+    int quater = b->file[b->no_cat-1].head.block_max / CAT_MAX;
     char *cut = dst_buf + quater * 2;
     char *maxp = dst_buf + b->file[b->no_cat-1].head.block_max;
     char *half1 = 0;
@@ -326,17 +632,27 @@ int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
             char *dst_item = 0;
             char *dst_0 = dst;
             char *lookahead_next;
-            int lookahead_mode;
             int d = -1;
             
             if (lookahead_item)
                 d = (*b->method->compare_item)(file_item_buf, lookahead_item);
             
-            if (d > 0)  
+            if (d > 0)
+            {
                 dst_item = lookahead_item;
+                if (!*lookahead_mode)
+                {
+                    yaz_log (LOG_WARN, "isamb: Inconsistent register (1)");
+                    assert (*lookahead_mode);
+                }
+            }
             else
                 dst_item = file_item_buf;
-            if (!half1 && dst > cut)   
+            if (!*lookahead_mode && d == 0)
+            {
+                p->dirty = 1;
+            }
+            else if (!half1 && dst > cut)
             {
                 char *dst_item_0 = dst_item;
                 half1 = dst; /* candidate for splitting */
@@ -362,15 +678,15 @@ int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
                     lookahead_next = lookahead_item;
                     if (!(*stream->read_item)(stream->clientData,
                                               &lookahead_next,
-                                              &lookahead_mode))
+                                              lookahead_mode))
                     {
                         lookahead_item = 0;
                         more = 0;
                     }
-                    if (max_item &&
+                    if (lookahead_item && max_item &&
                         (*b->method->compare_item)(max_item, lookahead_item) <= 0)
                     {
-			yaz_log (LOG_LOG, "max_item 1");
+                        /* max_item 1 */
                         lookahead_item = 0;
                     }
                     
@@ -381,7 +697,7 @@ int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
             {
                 lookahead_next = lookahead_item;
                 if (!(*stream->read_item)(stream->clientData,
-                                          &lookahead_next, &lookahead_mode))
+                                          &lookahead_next, lookahead_mode))
                 {
                     lookahead_item = 0;
                     more = 0;
@@ -403,17 +719,21 @@ int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
     maxp = dst_buf + b->file[b->no_cat-1].head.block_max + quater;
     while (lookahead_item)
     {
-        int lookahead_mode;
         char *dst_item = lookahead_item;
         char *dst_0 = dst;
         
         if (max_item &&
             (*b->method->compare_item)(max_item, lookahead_item) <= 0)
         {
- 	    yaz_log (LOG_LOG, "max_item 2");
+            /* max_item 2 */
             break;
         }
-        if (!half1 && dst > cut)   
+        if (!*lookahead_mode)
+        {
+            yaz_log (LOG_WARN, "isamb: Inconsistent register (2)");
+            abort();
+        }
+        else if (!half1 && dst > cut)   
         {
             char *dst_item_0 = dst_item;
             half1 = dst; /* candidate for splitting */
@@ -437,7 +757,7 @@ int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
             p->dirty = 1;
         dst_item = lookahead_item;
         if (!(*stream->read_item)(stream->clientData, &dst_item,
-                                  &lookahead_mode))
+                                  lookahead_mode))
         {
             lookahead_item = 0;
             more = 0;
@@ -448,6 +768,7 @@ int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
         new_size > b->file[p->cat].head.block_max)
     {
         /* non-btree block will be removed */
+        p->deleted = 1;
         close_block (b, p);
         /* delete it too!! */
         p = 0; /* make a new one anyway */
@@ -503,25 +824,67 @@ int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
 }
 
 int insert_sub (ISAMB b, struct ISAMB_block **p, void *new_item,
-                ISAMC_I stream,
+                int *mode,
+                ISAMC_I *stream,
                 struct ISAMB_block **sp,
                 void *sub_item, int *sub_size,
                 void *max_item)
 {
     if (!*p || (*p)->leaf)
-        return insert_leaf (b, p, new_item, stream, sp, sub_item, sub_size, 
-                            max_item);
+        return insert_leaf (b, p, new_item, mode, stream, sp, sub_item, 
+                            sub_size, max_item);
     else
-        return insert_int (b, *p, new_item, stream, sp, sub_item, sub_size);
+        return insert_int (b, *p, new_item, mode, stream, sp, sub_item,
+                           sub_size, max_item);
+}
+
+int isamb_unlink (ISAMB b, ISAMC_P pos)
+{
+    struct ISAMB_block *p1;
+
+    if (!pos)
+	return 0;
+    p1 = open_block(b, pos);
+    p1->deleted = 1;
+    if (!p1->leaf)
+    {
+	int sub_p;
+	int item_len;
+	char *src = p1->bytes + p1->offset;
+
+	decode_ptr(&src, &sub_p);
+	isamb_unlink(b, sub_p);
+	
+	while (src != p1->bytes + p1->size)
+	{
+	    decode_ptr(&src, &item_len);
+	    src += item_len;
+	    decode_ptr(&src, &sub_p);
+	    isamb_unlink(b, sub_p);
+	}
+    }
+    close_block(b, p1);
+    return 0;
 }
 
-int isamb_merge (ISAMB b, ISAMC_P pos, ISAMC_I stream)
+int isamb_merge (ISAMB b, ISAMC_P pos, ISAMC_I *stream)
 {
     char item_buf[DST_ITEM_MAX];
     char *item_ptr;
     int i_mode;
     int more;
 
+    if (b->cache < 0)
+    {
+        int more = 1;
+        while (more)
+        {
+            item_ptr = item_buf;
+            more =
+                (*stream->read_item)(stream->clientData, &item_ptr, &i_mode);
+        }
+        return 1;
+    }
     item_ptr = item_buf;
     more = (*stream->read_item)(stream->clientData, &item_ptr, &i_mode);
     while (more)
@@ -532,7 +895,7 @@ int isamb_merge (ISAMB b, ISAMC_P pos, ISAMC_I stream)
         
         if (pos)
             p = open_block (b, pos);
-        more = insert_sub (b, &p, item_buf, stream, &sp,
+        more = insert_sub (b, &p, item_buf, &i_mode, stream, &sp,
                             sub_item, &sub_size, 0);
         if (sp)
         {    /* increase level of tree by one */
@@ -558,42 +921,155 @@ int isamb_merge (ISAMB b, ISAMC_P pos, ISAMC_I stream)
     return pos;
 }
 
-ISAMB_PP isamb_pp_open (ISAMB isamb, ISAMB_P pos)
+ISAMB_PP isamb_pp_open_x (ISAMB isamb, ISAMB_P pos, int *level)
 {
     ISAMB_PP pp = xmalloc (sizeof(*pp));
+    int i;
 
     pp->isamb = isamb;
-    pp->block = xmalloc (10 * sizeof(*pp->block));
+    pp->block = xmalloc (ISAMB_MAX_LEVEL * sizeof(*pp->block));
 
+    pp->pos = pos;
     pp->level = 0;
+    pp->maxlevel=0;
+    pp->total_size = 0;
+    pp->no_blocks = 0;
+    pp->skipped_numbers=0;
+    pp->returned_numbers=0;
+    for (i=0;i<ISAMB_MAX_LEVEL;i++)
+        pp->skipped_nodes[i] = pp->accessed_nodes[i]=0;
     while (1)
     {
         struct ISAMB_block *p = open_block (isamb, pos);
         char *src = p->bytes + p->offset;
         pp->block[pp->level] = p;
 
-        if (p->bytes[0]) /* leaf */
+        pp->total_size += p->size;
+        pp->no_blocks++;
+        if (p->leaf)
             break;
 
+                                        
         decode_ptr (&src, &pos);
         p->offset = src - p->bytes;
         pp->level++;
+        pp->accessed_nodes[pp->level]++; 
     }
     pp->block[pp->level+1] = 0;
+    pp->maxlevel=pp->level;
+    if (level)
+        *level = pp->level;
     return pp;
 }
 
-void isamb_pp_close (ISAMB_PP pp)
+ISAMB_PP isamb_pp_open (ISAMB isamb, ISAMB_P pos)
+{
+    return isamb_pp_open_x (isamb, pos, 0);
+}
+
+void isamb_pp_close_x (ISAMB_PP pp, int *size, int *blocks)
 {
     int i;
     if (!pp)
         return;
+    logf(LOG_DEBUG,"isamb_pp_close lev=%d returned %d values, skipped %d",
+        pp->maxlevel, pp->skipped_numbers, pp->returned_numbers);
+    for (i=pp->maxlevel;i>=0;i--)
+        if ( pp->skipped_nodes[i] || pp->accessed_nodes[i])
+            logf(LOG_DEBUG,"isamb_pp_close  level leaf-%d: %d read, %d skipped", i,
+                 pp->accessed_nodes[i], pp->skipped_nodes[i]);
+    pp->isamb->skipped_numbers += pp->skipped_numbers;
+    pp->isamb->returned_numbers += pp->returned_numbers;
+    for (i=pp->maxlevel;i>=0;i--)
+    {
+        pp->isamb->accessed_nodes[i] += pp->accessed_nodes[i];
+        pp->isamb->skipped_nodes[i] += pp->skipped_nodes[i];
+    }
+    if (size)
+        *size = pp->total_size;
+    if (blocks)
+        *blocks = pp->no_blocks;
     for (i = 0; i <= pp->level; i++)
         close_block (pp->isamb, pp->block[i]);
     xfree (pp->block);
     xfree (pp);
 }
 
+int isamb_block_info (ISAMB isamb, int cat)
+{
+    if (cat >= 0 && cat < isamb->no_cat)
+        return isamb->file[cat].head.block_size;
+    return -1;
+}
+
+void isamb_pp_close (ISAMB_PP pp)
+{
+    isamb_pp_close_x (pp, 0, 0);
+}
+
+/* simple recursive dumper .. */
+static void isamb_dump_r (ISAMB b, ISAMB_P pos, void (*pr)(const char *str),
+			  int level)
+{
+    char buf[1024];
+    char prefix_str[1024];
+    if (pos)
+    {
+	struct ISAMB_block *p = open_block (b, pos);
+	sprintf(prefix_str, "%*s %d cat=%d size=%d max=%d", level*2, "",
+		pos, p->cat, p->size, b->file[p->cat].head.block_max);
+	(*pr)(prefix_str);
+	sprintf(prefix_str, "%*s %d", level*2, "", pos);
+	if (p->leaf)
+	{
+	    while (p->offset < p->size)
+	    {
+		char *src = p->bytes + p->offset;
+		char *dst = buf;
+		(*b->method->code_item)(ISAMC_DECODE, p->decodeClientData,
+					&dst, &src);
+		(*b->method->log_item)(LOG_DEBUG, buf, prefix_str);
+		p->offset = src - (char*) p->bytes;
+	    }
+	    assert(p->offset == p->size);
+	}
+	else
+	{
+	    char *src = p->bytes + p->offset;
+	    int sub;
+	    int item_len;
+
+	    decode_ptr (&src, &sub);
+	    p->offset = src - (char*) p->bytes;
+
+	    isamb_dump_r(b, sub, pr, level+1);
+	    
+	    while (p->offset < p->size)
+	    {
+		decode_ptr (&src, &item_len);
+		(*b->method->log_item)(LOG_DEBUG, src, prefix_str);
+		src += item_len;
+		decode_ptr (&src, &sub);
+		
+		p->offset = src - (char*) p->bytes;
+		
+		isamb_dump_r(b, sub, pr, level+1);
+	    }		
+	}
+	close_block(b,p);
+    }
+}
+
+void isamb_dump (ISAMB b, ISAMB_P pos, void (*pr)(const char *str))
+{
+    return isamb_dump_r(b, pos, pr, 0);
+}
+
+#if 0
+/* Old isamb_pp_read that Adam wrote, kept as a reference in case we need to
+   debug the more complex pp_read that also forwards. May be deleted near end
+   of 2004, if it has not shown to be useful */
+
 int isamb_pp_read (ISAMB_PP pp, void *buf)
 {
     char *dst = buf;
@@ -613,7 +1089,7 @@ int isamb_pp_read (ISAMB_PP pp, void *buf)
             pp->block[pp->level] = 0;
             (pp->level)--;
             p = pp->block[pp->level];
-            assert (p->bytes[0] == 0);  /* must be int */
+            assert (!p->leaf);  
         }
         src = p->bytes + p->offset;
         
@@ -628,8 +1104,11 @@ int isamb_pp_read (ISAMB_PP pp, void *buf)
         while (1)
         {
             pp->block[pp->level] = p = open_block (pp->isamb, pos);
+
+            pp->total_size += p->size;
+            pp->no_blocks++;
             
-            if (p->leaf) /* leaf */
+            if (p->leaf) 
             {
                 break;
             }
@@ -640,14 +1119,411 @@ int isamb_pp_read (ISAMB_PP pp, void *buf)
         }
     }
     assert (p->offset < p->size);
-    assert (p->bytes[0]);
+    assert (p->leaf);
     src = p->bytes + p->offset;
     (*pp->isamb->method->code_item)(ISAMC_DECODE, p->decodeClientData,
                                     &dst, &src);
     p->offset = src - (char*) p->bytes;
+    /* key_logdump_txt(LOG_DEBUG,buf, "isamb_pp_read returning 1"); */
+    return 1;
+}
+
+#else
+int isamb_pp_read (ISAMB_PP pp, void *buf)
+{
+    return isamb_pp_forward(pp,buf,0);
+}
+#endif
+
+#define NEW_FORWARD 0
+#if NEW_FORWARD
+
+#define ISAMB_DEBUG 1  /* while coding this part */
+
+static int isamb_pp_read_on_leaf(ISAMB_PP pp, void *buf)
+{ /* reads the next item on the current leaf, returns 0 if end of leaf*/
+    struct ISAMB_block *p = pp->block[pp->level];
+    char *dst;
+    char *src;
+    if (p->offset == p->size) {
+#if ISAMB_DEBUG
+        logf(LOG_DEBUG,"isamb_pp_read_on_leaf returning 0 on node %d",p->pos);
+#endif
+        return 0; /* at end of leaf */
+    }
+    src=p->bytes + p->offset;
+    dst=buf;
+    (*pp->isamb->method->code_item)
+           (ISAMC_DECODE, p->decodeClientData,&dst, &src);
+    p->offset = src - (char*) p->bytes;
+#if ISAMB_DEBUG
+    (*pp->isamb->method->log_item)(LOG_DEBUG, buf, "read_on_leaf returning 1");
+#endif
+    return 1;
+} /* read_on_leaf */
+
+
+static int isamb_pp_climb_level(ISAMB_PP pp, int *pos)
+{ /* climbs higher in the tree, until finds a level with data left */
+  /* returns the node to (consider to) descend to in *pos) */
+    struct ISAMB_block *p = pp->block[pp->level];
+    char *src;
+    int item_len;
+    assert(p->offset <= p->size);
+    if (pp->level==0)
+    {
+#if ISAMB_DEBUG
+        logf(LOG_DEBUG,"isamb_pp_climb_level returning 0 at root");
+        return 0;
+#endif
+    }
+    close_block(pp->isamb, pp->block[pp->level]);
+    pp->block[pp->level]=0;
+    (pp->level)--;
+    p=pp->block[pp->level];
+    logf(LOG_DEBUG,"isamb_pp_climb_level climbed to node %d ofs=%d",
+                    p->pos, p->offset);
+    assert (!p->leaf);
+    assert (p->offset <= p->size);
+    if (p->offset == p->size ) {
+        /* we came from the last pointer, climb on */
+        if (!isamb_pp_climb_level(pp,pos))
+            return 0;
+        p=pp->block[pp->level];
+    }
+    /* skip the child we just came from */
+    assert (p->offset < p->size );
+    src=p->bytes + p->offset;
+    decode_ptr(&src, &item_len);
+    src += item_len;
+    decode_ptr(&src, pos);
+    p->offset=src - (char *)p->bytes;
     return 1;
+} /* climb_level */
+
+
+static int isamb_pp_forward_unode(ISAMB_PP pp, int pos, const void *untilbuf)
+{ /* scans a upper node until it finds a child <= untilbuf */
+  /* pp points to the key value, as always. pos is the child read from */
+  /* the buffer */
+  /* if all values are too small, returns the last child in the node */
+  /* FIXME - this can be detected, and avoided by looking at the */
+  /* parent node, but that gets messy. Presumably the cost is */
+  /* pretty low anyway */
+    struct ISAMB_block *p = pp->block[pp->level];
+    char *src=p->bytes + p->offset;
+    int item_len;
+    int cmp;
+    int nxtpos;
+    assert(!p->leaf);
+    assert(p->offset <= p->size);
+    if (p->offset == p->size)
+        return pos; /* already at the end of it */
+    while(p->offset < p->size) {
+        decode_ptr(&src,&item_len);
+        cmp=(*pp->isamb->method->compare_item)(untilbuf,src);
+        src+=item_len;
+        decode_ptr(&src,&nxtpos);
+        if (cmp<2)
+        {
+            return pos;
+        } /* found one */
+        pos=nxtpos;
+        p->offset=src-(char*)p->bytes;
+    }
+    return pos; /* that's the last one in the line */
+    
+} /* forward_unode */
+
+static void isamb_pp_descend_to_leaf(ISAMB_PP pp, int pos, const void *untilbuf)
+{ /* climbs down the tree, from pos, to the leftmost leaf */
+    struct ISAMB_block *p = pp->block[pp->level];
+    char *src;
+    assert(!p->leaf);
+    ++(pp->level);
+    p=open_block(pp->isamb, pos);
+    pp->block[pp->level]=p;
+    ++(pp->accessed_nodes[pp->maxlevel-pp->level]);
+    ++(pp->no_blocks);
+#if ISAMB_DEBUG
+    logf(LOG_DEBUG,"isamb_pp_descend_to_leaf "
+                   "got lev %d node %d lf=%d", 
+                   pp->level, p->pos, p->leaf);
+#endif
+    if (p->leaf)
+        return;
+    assert (p->offset==0 );
+    src=p->bytes + p->offset;
+    decode_ptr(&src, &pos);
+    p->offset=src-(char*)p->bytes;
+    if (untilbuf)
+        pos=isamb_pp_forward_unode(pp,pos,untilbuf);
+    isamb_pp_descend_to_leaf(pp,pos,untilbuf);
+} /* descend_to_leaf */
+
+static int isamb_pp_find_next_leaf(ISAMB_PP pp)
+{ /* finds the next leaf by climbing up and down */
+    int pos;
+    if (!isamb_pp_climb_level(pp,&pos))
+        return 0;
+    isamb_pp_descend_to_leaf(pp, pos,0);
+    return 1;
+}
+static int isamb_pp_forward_on_leaf(ISAMB_PP pp, void *buf, const void *untilbuf)
+{ /* forwards on the current leaf, returns 0 if not found */
+    int cmp;
+    int skips=0;
+    while (1){
+        if (!isamb_pp_read_on_leaf(pp,buf))
+            return 0;
+        /* FIXME - this is an extra function call, inline the read? */
+        cmp=(*pp->isamb->method->compare_item)(untilbuf,buf);
+        if (cmp <2){  /* found a good one */
+#if ISAMB_DEBUG
+            if (skips)
+                logf(LOG_DEBUG, "isam_pp_fwd_on_leaf skipped %d items",skips);
+#endif
+            pp->returned_numbers++;
+            return 1;
+        }
+        pp->skipped_numbers++;
+        skips++;
+    }
+} /* forward_on_leaf */
+
+static int isamb_pp_climb_desc(ISAMB_PP pp, void *buf, const void *untilbuf)
+{ /* climbs up and descends to a leaf where values >= *untilbuf are found */
+    int pos;
+    if (!isamb_pp_climb_level(pp,&pos))
+        return 0;
+    isamb_pp_descend_to_leaf(pp, pos,untilbuf);
+    return 1;
+} /* climb_desc */
+
+int isamb_pp_forward (ISAMB_PP pp, void *buf, const void *untilbuf)
+{
+#if ISAMB_DEBUG
+    struct ISAMB_block *p = pp->block[pp->level];
+    assert(p->leaf);
+#endif
+    if (untilbuf) {
+        if (isamb_pp_forward_on_leaf( pp, buf, untilbuf))
+            return 1;
+        if (! isamb_pp_climb_desc( pp, buf, untilbuf))
+            return 0; /* could not find a leaf */
+        do{
+            if (isamb_pp_forward_on_leaf( pp, buf, untilbuf))
+                return 1;
+        }while ( isamb_pp_find_next_leaf(pp));
+        return 0; /* could not find at all */
+    }
+    else { /* no untilbuf, a straight read */
+        /* FIXME - this should be moved
+         * directly into the pp_read */
+        /* keeping here now, to keep same
+         * interface as the old fwd */
+        if (isamb_pp_read_on_leaf( pp, buf))
+            return 1;
+        if (isamb_pp_find_next_leaf(pp))
+            return isamb_pp_read_on_leaf(pp, buf);
+        else
+            return 0;
+    }
+} /* isam_pp_forward (new version) */
+
+#else
+
+int isamb_pp_forward (ISAMB_PP pp, void *buf, const void *untilbuf)
+{
+    /* pseudocode:
+     *   while 1
+     *     while at end of node
+     *       climb higher. If out, return 0
+     *     while not on a leaf (and not at its end)
+     *       decode next
+     *       if cmp
+     *         descend to node
+     *     decode next
+     *     if cmp
+     *       return 1
+     */
+     /* 
+      * The upper nodes consist of a sequence of nodenumbers and keys
+      * When opening a block,  the first node number is read in, and
+      * offset points to the first key, which is the upper limit of keys
+      * in the node just read.
+      */
+    char *dst = buf;
+    char *src;
+    struct ISAMB_block *p = pp->block[pp->level];
+    int cmp;
+    int item_len;
+    int pos;
+    int nxtpos;
+    int descending=0; /* used to prevent a border condition error */
+    if (!p)
+        return 0;
+#if ISAMB_DEBUG
+    logf(LOG_DEBUG,"isamb_pp_forward starting [%p] p=%d",pp,p->pos);
+    
+    (*pp->isamb->method->log_item)(LOG_DEBUG, untilbuf, "until");
+    (*pp->isamb->method->log_item)(LOG_DEBUG, buf, "buf");
+#endif
+
+    while (1)
+    {
+        while ( (p->offset == p->size) && !descending )
+        {  /* end of this block - climb higher */
+	    assert (p->offset <= p->size);
+#if ISAMB_DEBUG
+            logf(LOG_DEBUG,"isamb_pp_forward climbing from l=%d",
+                            pp->level);
+#endif
+            if (pp->level == 0)
+            {
+#if ISAMB_DEBUG
+                logf(LOG_DEBUG,"isamb_pp_forward returning 0 at root");
+#endif
+                return 0; /* at end of the root, nothing left */
+            }
+            close_block(pp->isamb, pp->block[pp->level]);
+            pp->block[pp->level]=0;
+            (pp->level)--;
+            p=pp->block[pp->level];
+#if ISAMB_DEBUG
+            logf(LOG_DEBUG,"isamb_pp_forward climbed to node %d off=%d",
+                            p->pos, p->offset);
+#endif
+            assert(!p->leaf);
+	    assert(p->offset <= p->size);
+            /* skip the child we have handled */
+            if (p->offset != p->size)
+            { 
+                src = p->bytes + p->offset;
+                decode_ptr(&src, &item_len);
+#if ISAMB_DEBUG		
+		(*pp->isamb->method->log_item)(LOG_DEBUG, src,
+					       " isamb_pp_forward "
+					       "climb skipping old key");
+#endif
+                src += item_len;
+                decode_ptr(&src,&pos);
+                p->offset = src - (char*) p->bytes;
+                break; /* even if this puts us at the end of the block, we
+			  need to descend to the last pos. UGLY coding,
+			  clean up some day */
+            }
+        }
+        if (!p->leaf)
+        { 
+            src = p->bytes + p->offset;
+            if (p->offset == p->size)
+                cmp=-2 ; /* descend to the last node, as we have
+			    no value to cmp */
+            else
+            {
+                decode_ptr(&src, &item_len);
+#if ISAMB_DEBUG
+                logf(LOG_DEBUG,"isamb_pp_forward (B) on a high node. "
+		     "ofs=%d sz=%d nxtpos=%d ",
+                        p->offset,p->size,pos);
+		(*pp->isamb->method->log_item)(LOG_DEBUG, src, "");
+#endif
+                if (untilbuf)
+                    cmp=(*pp->isamb->method->compare_item)(untilbuf,src);
+                else
+                    cmp=-2;
+                src += item_len;
+                decode_ptr(&src,&nxtpos);
+            }
+            if (cmp<2)
+            { 
+#if ISAMB_DEBUG
+                logf(LOG_DEBUG,"isambb_pp_forward descending l=%d p=%d ",
+                            pp->level, pos);
+#endif
+                descending=1; /* prevent climbing for a while */
+                ++(pp->level);
+                p = open_block(pp->isamb,pos);
+                pp->block[pp->level] = p ;
+                pp->total_size += p->size;
+                (pp->accessed_nodes[pp->maxlevel - pp->level])++;
+                pp->no_blocks++;
+                if ( !p->leaf)
+                { /* block starts with a pos */
+                    src = p->bytes + p->offset;
+                    decode_ptr(&src,&pos);
+                    p->offset=src-(char*) p->bytes;
+#if ISAMB_DEBUG
+                    logf(LOG_DEBUG,"isamb_pp_forward: block %d starts with %d",
+                                    p->pos, pos);
+#endif
+                } 
+            } /* descend to the node */
+            else
+            { /* skip the node */
+                p->offset = src - (char*) p->bytes;
+                pos=nxtpos;
+                (pp->skipped_nodes[pp->maxlevel - pp->level -1])++;
+#if ISAMB_DEBUG
+                logf(LOG_DEBUG,
+                    "isamb_pp_forward: skipping block on level %d, noting "
+		     "on %d (%d)",
+                    pp->level, pp->maxlevel - pp->level-1 , 
+                    pp->skipped_nodes[pp->maxlevel - pp->level-1 ]);
+#endif
+                /* 0 is always leafs, 1 is one level above leafs etc, no
+                 * matter how high tree */
+            }
+        } /* not on a leaf */
+        else
+        { /* on a leaf */
+	    if (p->offset == p->size) { 
+		descending = 0;
+	    }
+	    else
+	    {
+		assert (p->offset < p->size);
+		src = p->bytes + p->offset;
+		dst=buf;
+		(*pp->isamb->method->code_item)(ISAMC_DECODE, p->decodeClientData,
+						&dst, &src);
+		p->offset = src - (char*) p->bytes;
+		if (untilbuf)
+		    cmp=(*pp->isamb->method->compare_item)(untilbuf,buf);
+		else
+		    cmp=-2;
+#if ISAMB_DEBUG
+		logf(LOG_DEBUG,"isamb_pp_forward on a leaf. cmp=%d", 
+		     cmp);
+		(*pp->isamb->method->log_item)(LOG_DEBUG, buf, "");
+#endif
+		if (cmp <2)
+		{
+#if ISAMB_DEBUG
+		    if (untilbuf)
+		    {
+			(*pp->isamb->method->log_item)(
+			    LOG_DEBUG, buf,  "isamb_pp_forward returning 1");
+		    }
+		    else
+		    {
+			(*pp->isamb->method->log_item)(
+			    LOG_DEBUG, buf, "isamb_pp_read returning 1 (fwd)");
+		    }
+#endif
+		    pp->returned_numbers++;
+		    return 1;
+		}
+		else
+		    pp->skipped_numbers++;
+	    }
+        } /* leaf */
+    } /* main loop */
 }
 
+#endif
+
 int isamb_pp_num (ISAMB_PP pp)
 {
     return 1;