significant reduction of raw access to the metadata structure

Force-Push: yes
Change-Id: Ibdf713ba0e66c7a3b4632dacdfa7f10733112b0a

1 files changed, 76 insertions, 45 deletions

diff --git a/transform.e b/transform.e
index 35a720c..bae74e2 100644
--- a/transform.e
+++ b/transform.e
@@ -2616,7 +2616,7 @@ allocate-transformation-state s" transformation-state" variable
 ~     ... + 0x00 - ... + 0x07               Data pointer
 ~     ... + 0x08 - ... + 0x0f               Referenced data length
 ~     ... + 0x10 - ... + 0x17               String pointer
-~ (entry fields repeat at successive offsets)
+~ (entry fields repeat at successive offsets, until...)
 ~     ... + 0x00 - ... + 0x07 (end)         Zero, used as a delimiter
 : hex-output-metadata-label-loop-buffer-start ;
 : hex-output-metadata-label-loop-buffer-length 8 + ;
@@ -2626,6 +2626,18 @@ allocate-transformation-state s" transformation-state" variable
 : hex-output-metadata-entry-string 2 8 * + ;
 : hex-output-metadata-next-entry 3 8 * + ;
 
+~   Initialize the contents of the output metadata to all zeroes. This is
+~ called from hex-transform at its top level, at the very start, to make sure
+~ everything is structurally valid. We can't store real values at that point,
+~ because they don't exist yet. The actual label-loop buffer, per its name,
+~ won't be allocated until label-loop is called, so we can't possibly know its
+~ address till then.
+: zero-hex-output-metadata
+  transformation-state transformation-state-output-metadata @
+  dup hex-output-metadata-label-loop-buffer-start 0 swap !
+  dup hex-output-metadata-label-loop-buffer-length 0 swap !
+  dup hex-output-metadata-first-entry 0 swap ! ;
+
 ~ (pointer -- boolean)
 : is-in-label-loop-buffer
   dup
@@ -2638,58 +2650,77 @@ allocate-transformation-state s" transformation-state" variable
   swap hex-output-metadata-label-loop-buffer-length @ +
   > && ;
 
+~ (data start, data length, string pointer, entry pointer --)
+: hex-output-metadata-entry!
+  dup hex-output-metadata-entry-string 3roll swap !
+  dup hex-output-metadata-entry-data-length 3roll swap !
+  dup hex-output-metadata-entry-data-start 3roll swap !
+  drop ;
+
+~ (entry pointer, data start, data length, string pointer
+~  -- next entry pointer)
+: pack-hex-output-metadata-entry
+  3 pick hex-output-metadata-entry!
+  hex-output-metadata-next-entry ;
+
 ~ (data start, data length, string pointer --)
 : add-hex-output-metadata-entry
-  transformation-state transformation-state-output-metadata @
-  hex-output-metadata-first-entry
-  { dup @ dup { dup 2 pick >= drop } if } {
-    hex-output-metadata-next-entry
-  } while
-  4 roll pack64 3roll pack64 swap pack64 0 pack64
-  drop ;
+  2 pick is-in-label-loop-buffer {
+    transformation-state transformation-state-output-metadata @
+    hex-output-metadata-first-entry
+    { dup @ dup { dup 2 pick >= drop } if } {
+      hex-output-metadata-next-entry
+    } while
 
-: add-hex-output-metadata-top-of-file-entries
+    4 unroll pack-hex-output-metadata-entry
+    0 pack64 drop
+  } { drop drop drop } if-else ;
+
+~   This is the followup to zero-hex-output-metadata, above. Once we do have
+~ the label-loop buffer, we need to create some default entries. This is
+~ called in the first label-loop iteration by hex-allocate-replacement, and
+~ it's called before subsequent iterations by the hook on reset-labels defined
+~ in hex-colon-alternate.
+~
+~   This overwrites whatever entries currently exist with the new ones, and
+~ adds a zero delimiter at the end.
+~
+~   It requires the header to have already been initialized; in particular it
+~ requires the label-loop buffer start pointer to be valid.
+: create-hex-output-metadata-top-of-file-entries
   transformation-state transformation-state-output-metadata @
   dup hex-output-metadata-label-loop-buffer-start @
   swap hex-output-metadata-first-entry
   ~ (label buffer start, metadata output point)
 
-  over pack64 ~ Entry data start
-  0 pack64    ~ Entry data length
+  over 0
   s"   This file is a commented hexadecimal representation of a compiled "
-  pack64      ~ Entry string
+  pack-hex-output-metadata-entry
 
-  over pack64 ~ Entry data start
-  0 pack64    ~ Entry data length
+  over 0
   s" program, the output of Evocation's hex transform. The comments are "
-  pack64      ~ Entry string
+  pack-hex-output-metadata-entry
 
-  over pack64 ~ Entry data start
-  0 pack64    ~ Entry data length
+  over 0
   s" intended to allow a human reader to audit it. You can convert it to a "
-  pack64      ~ Entry string
+  pack-hex-output-metadata-entry
 
-  over pack64 ~ Entry data start
-  0 pack64    ~ Entry data length
+  over 0
   s" runnable executable by piping it through the program named 'hex' and "
-  pack64      ~ Entry string
+  pack-hex-output-metadata-entry
 
-  over pack64 ~ Entry data start
-  0 pack64    ~ Entry data length
+  over 0
   s" chmodding the output 755. The difference between a source and a binary "
-  pack64      ~ Entry string
+  pack-hex-output-metadata-entry
 
-  over pack64 ~ Entry data start
-  0 pack64    ~ Entry data length
+  over 0
   s" is comments! Enjoy. :)"
-  pack64      ~ Entry string
+  pack-hex-output-metadata-entry
 
-  over pack64 ~ Entry data start
-  0 pack64    ~ Entry data length
-  s" " pack64 ~ Entry string
+  over 0 s" " pack-hex-output-metadata-entry
 
-  0 pack64    ~ End-of-entries delimiter
-  drop drop ;
+  0 swap ! ~ End-of-entries delimiter
+  drop ;
 
 : hex-tilde-alternate [ ' ~ entry-to-execution-token , ]
   ; make-immediate
@@ -2946,7 +2977,8 @@ allocate-transformation-state s" transformation-state" variable
     ~ of label-loop. We need to reinitialize all the metadata entries whenever
     ~ that happens, and reset-labels is a good semantic match for that
     ~ behavior, so it's a good place for the hook.
-    ' add-hex-output-metadata-top-of-file-entries entry-to-execution-token ,
+    ' create-hex-output-metadata-top-of-file-entries
+    entry-to-execution-token ,
     ~ Fall through to the inner implementation.
 
     ' ] entry-to-execution-token execute
@@ -3070,13 +3102,15 @@ allocate-transformation-state s" transformation-state" variable
   ~ (result pointer, size)
 
   transformation-state transformation-state-output-metadata @
-  ~ (result pointer, size, metadata pointer)
-  2 pick pack64  ~ Label buffer start
-  swap pack64    ~ Label buffer length
-  drop
+  hex-output-metadata-label-loop-buffer-length !
   ~ (result pointer)
 
-  add-hex-output-metadata-top-of-file-entries ;
+  dup
+  transformation-state transformation-state-output-metadata @
+  hex-output-metadata-label-loop-buffer-start !
+  ~ (result pointer)
+
+  create-hex-output-metadata-top-of-file-entries ;
 
 ~ ... then, we define the alternate.
 ~
@@ -3354,13 +3388,10 @@ 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 the notes above
-  ~ hex-output-metadata-* for details on its format.
-  transformation-state transformation-state-output-metadata @
-  0 pack64 ~ Label buffer start
-  0 pack64 ~ Label buffer length
-  0 pack64 ~ End-of-entries delimiter
-  drop
+  ~   We don't have the real values yet, so we can't create the initial
+  ~ entries in the output metadata, but we can and should zero it out to make
+  ~ sure everything else operating on it finds it well-formed.
+  zero-hex-output-metadata
 
   ~   It's important that the stack has nothing of ours on it that persists
   ~ across iterations, so that client code can add and remove stuff there as