abstract the hex transform's metadata low-level pointer manipulation

and move the docs on the data structure to where that is

Force-Push: yes
Change-Id: I607f2f9ce354026f27a8c6cbba020e29342fe450

1 files changed, 43 insertions, 18 deletions

diff --git a/transform.e b/transform.e
index f32448b..3a6e34c 100644
--- a/transform.e
+++ b/transform.e
@@ -2606,6 +2606,24 @@ allocate-transformation-state s" transformation-state" variable
 ~   The hex transform DOES NOT WORK yet. It's still in development.
 ~ TODO update this note when it does work
 
+~   The output metadata is a header structure followed by an array of
+~ entry structures, as follows:
+~
+~ (header start)
+~           0x00 - 0x07                     Label-loop buffer length
+~ (entry start)
+~     ... + 0x00 - ... + 0x07               Data pointer
+~     ... + 0x08 - ... + 0x0f               Referenced data length
+~     ... + 0x10 - ... + 0x17               String pointer
+~ (entry fields repeat at successive offsets)
+~     ... + 0x00 - ... + 0x07 (end)         Zero, used as a delimiter
+: hex-output-metadata-label-loop-buffer-length ;
+: hex-output-metadata-first-entry 8 + ;
+: hex-output-metadata-entry-data-start ;
+: hex-output-metadata-entry-data-length 8 + ;
+: hex-output-metadata-entry-string 2 8 * + ;
+: hex-output-metadata-next-entry 3 8 * + ;
+
 : hex-tilde-alternate [ ' ~ entry-to-execution-token , ]
   ; make-immediate
 
@@ -2708,18 +2726,8 @@ allocate-transformation-state s" transformation-state" variable
 ~ (length to write, base address --)
 : hex-sys-write-replacement
   { over } {
-    ~   The output metadata is a header structure followed by an array of
-    ~ entry structures, as follows:
-    ~
-    ~ (header start)
-    ~           0x00 - 0x07                     Output buffer length
-    ~ (entry start)
-    ~     ... + 0x00 - ... + 0x07               Data pointer
-    ~     ... + 0x08 - ... + 0x0f               Referenced data length
-    ~     ... + 0x10 - ... + 0x17               String pointer
-    ~ (entry fields repeat at successive offsets)
-    ~     ... + 0x00 - ... + 0x07 (end)         Zero, used as a delimiter
-    transformation-state transformation-state-output-metadata @ 8 +
+    transformation-state transformation-state-output-metadata @
+    hex-output-metadata-first-entry
     ~ (length remaining, current output address, metadata scan pointer)
     { dup @ dup { dup 2 pick >= drop } if
             ~ dup { dup 2 pick >= } if
@@ -2729,9 +2737,9 @@ allocate-transformation-state s" transformation-state" variable
         ~ We found a matching metadata entry.
         ~ (length remaining, current output address, metadata scan pointer)
 
-        dup 2 8 * + @ ." ~ " emitstring newline
+        dup hex-output-metadata-entry-string @ ." ~ " emitstring newline
       } if
-      3 8 * +
+      hex-output-metadata-next-entry
     } while
     drop
 
@@ -2862,6 +2870,23 @@ allocate-transformation-state s" transformation-state" variable
     exit
   } if
 
+  ~   Now we have a bunch of patches that keep track of output metadata. These
+  ~ are all Forth words, nothing too complicated about the actual patching.
+  dup s" packstring" stringcmp 0 = {
+    create dropstring
+    s" docol" find entry-to-execution-token execute ,
+    make-hidden
+
+    ~ (output point, string pointer)
+    ~ TODO DO NOT SUBMIT
+    ~ s" over" find entry-to-execution-token ,
+    ~ ' hex-sys-write-replacement entry-to-execution-token ,
+
+    ' ] entry-to-execution-token execute
+    exit
+  } if
+
+
   ~   If no special case matches, we fall back to just being a regular colon.
   ~ We already read the word name above, so we have to do the rest of the
   ~ steps ourselves as well.
@@ -3264,11 +3289,11 @@ allocate-transformation-state s" transformation-state" variable
   transformation-state transformation-state-output-metadata !
   ~ Now the stack has nothing of ours on it, so client code can do its thing.
 
-  ~   Initialize the contents of the output metadata. See
-  ~ hex-sys-write-replacement for more notes on its format.
+  ~   Initialize the contents of the output metadata. See the notes above
+  ~ hex-output-metadata-* for details on its format.
   transformation-state transformation-state-output-metadata @
-  0 pack64
-  0 pack64
+  0 pack64 ~ Output buffer length
+  0 pack64 ~ End-of-entries delimiter
   drop
 
   ~   It's important that the stack has nothing of ours on it that persists