Update the ASCII diagrams describing the tree structure for pointer lookups

* doc/tree.md (A picture): Update the Dave Barrett's ASCII diagrams
(from v3.7, 1994) to match the current BDWGC version.

diff --git a/doc/tree.md b/doc/tree.md
index cdf1aa7b558e507469b52d1422901a93a51d09c7..801638f226ba81fa4bca6b50c1ec7a74d55882d8 100644 (file)
--- a/doc/tree.md
+++ b/doc/tree.md
@@ -77,99 +77,99 @@ is contiguous and not excessively large.
 
 ## A picture
 
-The following is an _ASCII_ diagram of the data structure used by GC_base (as
-of GC v3.7, Apr 21, 1994). This was contributed by Dave Barrett.
-
-
-        63                  LOG_TOP_SZ[11]  LOG_BOTTOM_SZ[10]   LOG_HBLKSIZE[13]
-       +------------------+----------------+------------------+------------------+
-     p:|                  |   TL_HASH(hi)  |                  |   HBLKDISPL(p)   |
-       +------------------+----------------+------------------+------------------+
-        \-----------------------HBLKPTR(p)-------------------/
-        \------------hi-------------------/
-                          \______ ________/ \________ _______/ \________ _______/
-                                 V                   V                  V
-                                 |                   |                  |
-               GC_top_index[]    |                   |                  |
-     ---      +--------------+   |                   |                  |
-      ^       |              |   |                   |                  |
-      |       |              |   |                   |                  |
-     TOP      +--------------+<--+                   |                  |
-     _SZ   +-<|      []      | *                     |                  |
-    (items)|  +--------------+  if 0 < bi< HBLKSIZE  |                  |
-      |    |  |              | then large object     |                  |
-      |    |  |              | starts at the bi'th   |                  |
-      v    |  |              | HBLK before p.        |             i    |
-     ---   |  +--------------+                       |          (word-  |
-           v                                         |         aligned) |
-       bi= |GET_BI(p){->hash_link}->key==hi          |                  |
-           v                                         |                  |
-           |   (bottom_index)  \ scratch_alloc'd     |                  |
-           |   ( struct  bi )  / by get_index()      |                  |
-     ---   +->+--------------+                       |                  |
-      ^       |              |                       |                  |
-      ^       |              |                       |                  |
-     BOTTOM   |              |   ha=GET_HDR_ADDR(p)  |                  |
-    _SZ(items)+--------------+<----------------------+          +-------+
-      |   +--<|   index[]    |                                  |
-      |   |   +--------------+                      GC_obj_map: v
-      |   |   |              |              from      / +-+-+-----+-+-+-+-+  ---
-      v   |   |              |              GC_add   < 0| | |     | | | | |   ^
-     ---  |   +--------------+             _map_entry \ +-+-+-----+-+-+-+-+   |
-          |   |   asc_link   |                          +-+-+-----+-+-+-+-+ MAXOBJSZ
-          |   +--------------+                      +-->| | |  j  | | | | |  +1
-          |   |     key      |                      |   +-+-+-----+-+-+-+-+   |
-          |   +--------------+                      |   +-+-+-----+-+-+-+-+   |
-          |   |  hash_link   |                      |   | | |     | | | | |   v
-          |   +--------------+                      |   +-+-+-----+-+-+-+-+  ---
-          |                                         |   |<--MAX_OFFSET--->|
-          |                                         |         (bytes)
-    HDR(p)| GC_find_header(p)                       |   |<--MAP_ENTRIES-->|
-          |                           \ from        |    =HBLKSIZE/WORDSZ
-          |    (hdr) (struct hblkhdr) / alloc_hdr() |    (1024 on Alpha)
-          +-->+----------------------+              |    (8/16 bits each)
-    GET_HDR(p)| word   hb_sz (words) |              |
-              +----------------------+              |
-              | struct hblk *hb_next |              |
-              +----------------------+              |
-              |mark_proc hb_mark_proc|              |
-              +----------------------+              |
-              | char * hb_map        |>-------------+
-              +----------------------+
-              | ushort hb_obj_kind   |
-              +----------------------+
-              |   hb_last_reclaimed  |
-     ---      +----------------------+
-      ^       |                      |
-     MARK_BITS|       hb_marks[]     |  * if hdr is free, hb_sz is the size of
-    _SZ(words)|                      |  a heap chunk (struct hblk) of at least
-      v       |                      |  MININCR*HBLKSIZE bytes (below),
-     ---      +----------------------+  otherwise, size of each object in chunk.
+The following is an _ASCII_ diagram of the data structure used by GC_base. This was
+contributed originally by Dave Barrett.
+
+
+         63                  LOG_TOP_SZ[11]  LOG_BOTTOM_SZ[10]   LOG_HBLKSIZE[13]
+        +------------------+----------------+------------------+------------------+
+      p:|                  |   TL_HASH(hi)  |                  |   HBLKDISPL(p)   |
+        +------------------+----------------+------------------+------------------+
+         \-----------------------HBLKPTR(p)-------------------/
+         \------------hi-------------------/
+                           \______ ________/ \________ _______/ \________ _______/
+                                  V                   V                  V
+                                  |                   |                  |
+                GC_top_index[]    |                   |                  |
+      ---      +--------------+   |                   |                  |
+       ^       |              |   |                   |                  |
+       |       |              |   |                   |                  |
+      TOP_SZ   +--------------+<--+                   |                  |
+     (items)+-<|      []      | *                     |                  |
+       |    |  +--------------+  if 0 < bi< HBLKSIZE  |                  |
+       |    |  |              | then large object     |                  |
+       |    |  |              | starts at the bi'th   |                  |
+       v    |  |              | hblk before p.        |             i    |
+      ---   |  +--------------+                       |          (word-  |
+            v                                         |         aligned) |
+        bi= |GET_BI(p){->hash_link}->key==hi          |                  |
+            v                                         |                  |
+            |   (bottom_index)  \ scratch_alloc'd     |                  |
+            |   ( struct  bi )  / by get_index()      |                  |
+      ---   +->+--------------+                       |                  |
+       ^       |              |                       |                  |
+       |       |              |                       |                  |
+    BOTTOM_SZ  |              |   ha=GET_HDR_ADDR(p)  |                  |
+     (items)   +--------------+<----------------------+          +-------+
+       |   +--<|   index[]    |                                  |
+       |   |   +--------------+                      GC_obj_map: v
+       |   |   |              |              from      / +-+-+-----+-+-+-+-+  ---
+       v   |   |              |       GC_add_map_entry <0| | |     | | | | |   ^
+      ---  |   +--------------+                        \ +-+-+-----+-+-+-+-+   |
+           |   |   asc_link   |                          +-+-+-----+-+-+-+-+ MAXOBJGRANULES
+           |   +--------------+                      +-->| | |  j  | | | | |  +1
+           |   |     key      |                      |   +-+-+-----+-+-+-+-+   |
+           |   +--------------+                      |   +-+-+-----+-+-+-+-+   |
+           |   |  hash_link   |                      |   | | |     | | | | |   v
+           |   +--------------+                      |   +-+-+-----+-+-+-+-+  ---
+           |                                         |   |<----MAP_LEN---->|
+           |                                         |   =HBLKSIZE/GRANULE_BYTES
+     HDR(p)| GC_find_header(p)                       |    (1024 on Alpha)
+           |                           \ from        |    (8/16 bits each)
+           |    (hdr) (struct hblkhdr) / alloc_hdr() |
+           +--->+----------------------+             |
+      GET_HDR(p)| word   hb_sz (words) |             |
+                +----------------------+             |
+                | struct hblk *hb_next |             |
+                +----------------------+             |
+                | word hb_descr        |             |
+                +----------------------+             |
+                | char * hb_map        |>------------+
+                +----------------------+
+                | ushort hb_obj_kind   |
+                +----------------------+
+                |   hb_last_reclaimed  |
+       ---      +----------------------+
+        ^       |                      |
+    MARK_BITS_SZ|       hb_marks[]     |  * if hdr is free, hb_sz is the size of
+      (words)   |                      |  a heap chunk (struct hblk) of at least
+        v       |                      |  MININCR*HBLKSIZE bytes (below),
+       ---      +----------------------+  otherwise, size of each object in chunk.
 
 
 Dynamic data structures above are interleaved throughout the heap in blocks
 of size `MININCR * HBLKSIZE` bytes as done by `gc_scratch_alloc` which cannot
-be freed; free lists are used (e.g. `alloc_hdr`). `HBLK`'s below are
+be freed; free lists are used (e.g. `alloc_hdr`). `hblk`'s below are
 collected.
 
 
-                  (struct hblk)                                  HDR_BYTES
-     ---      +----------------------+ < HBLKSIZE  ---            (bytes)
-      ^       +-----hb_body----------+ (and WORDSZ) ^         ---   ---
-      |       |                      |   aligned    |          ^     ^
-      |       |                      |              |        hb_sz   |
-      |       |                      |              |       (words)  |
-      |       |      Object 0        |              |          |     |
-      |       |                      |            i |(word-    v     |
-      |       + - - - - - - - - - - -+ ---   (bytes)|aligned) ---    |
-      |       |                      |  ^           |          ^     |
-      |       |                      |  j (words)   |          |     |
-      n *     |      Object 1        |  v           v        hb_sz BODY_SZ
-     HBLKSIZE |                      |---------------          |   (words)
-     (bytes)  |                      |                         v   MAX_OFFSET
-      |       + - - - - - - - - - - -+                        ---  (bytes)
-      |       |                      | !ALL_INTERIOR_POINTERS  ^     |
-      |       |                      | sets j only for       hb_sz   |
-      |       |      Object N        | valid object offsets.   |     |
-      v       |                      | All objects WORDSZ      v     v
-     ---      +----------------------+ aligned.               ---   ---
+                 (struct hblk)
+      ---    +----------------------+ < HBLKSIZE  ---
+       ^     +-----hb_body----------+ (and WORDSZ) ^         ---   ---
+       |     |                      |   aligned    |          ^     ^
+       |     |                      |              |        hb_sz   |
+       |     |                      |              |       (words)  |
+       |     |      Object 0        |              |          |     |
+       |     |                      |            i |(word-    v     |
+       |     + - - - - - - - - - - -+ ---   (bytes)|aligned) ---    |
+       |     |                      |  ^           |          ^     |
+       |     |                      |  j (words)   |          |     |
+     n *     |      Object 1        |  v           v        hb_sz HBLKSIZE/BYTES_PER_WORD
+    HBLKSIZE |                      |---------------          |   (words)
+    (bytes)  |                      |                         v     |
+       |     + - - - - - - - - - - -+                        ---    |
+       |     |                      | !ALL_INTERIOR_POINTERS  ^     |
+       |     |                      | sets j only for       hb_sz   |
+       |     |      Object N        | valid object offsets.   |     |
+       v     |                      | All objects WORDSZ-     v     v
+      ---    +----------------------+ aligned.               ---   ---