the interpreter fully compiles now

doesn't work quite yet. close :)

Force-Push: yes
Change-Id: I71b6e788790fe2ca8e07dae95e9ad6e39d0664c0

1 files changed, 49 insertions, 1 deletions

diff --git a/input.e b/input.e
index 5cf2aeb..c7a1c02 100644
--- a/input.e
+++ b/input.e
@@ -166,7 +166,7 @@
   buffer-logical-start @ 8@ ;
 
 
-~ (metadata pointer)
+~ (metadata pointer -- byte or 0)
 : key-from
   dup peek-from
   ~ (metadata pointer, result byte)
@@ -175,6 +175,54 @@
   swap consume-from ;
 
 
+~   If the buffer is empty, make sure its logical position is at the
+~ physical start. Otherwise, leave it alone.
+~
+~ In:
+~   pointer to buffer metadata
+: normalize-buffer
+  dup buffer-logical-length @ 0 =
+  { dup buffer-physical-start @ swap
+    buffer-logical-start ! } { drop } if-else
+  ;
+
+
+~   Find the next contiguous area of a buffer to write incoming data to.
+~ This will begin at the logical end. Depending on the order things are in,
+~ the available space might run from there to the physical end, or to the
+~ logical start. Those are the only two possibilities.
+~
+~   If the buffer is full, this will return as normal but the length will
+~ be zero. The caller should make sure to respect that.
+~
+~ In:
+~   pointer to buffer metadata
+~ Out:
+~   destination start
+~   destination length
+: compute-next-buffer-free-block
+  dup buffer-physical-start @ swap dup buffer-physical-length @
+  swap 3unroll + swap
+~ (physical end, metadata pointer)
+  dup buffer-logical-start @ swap dup buffer-logical-length @
+  swap 3unroll + swap 3unroll
+~ (metadata pointer, physical end, logical end not yet wrapped)
+
+
+~ (metadata pointer --)
+: refill-input-buffer-from-stdin
+  dup normalize-buffer
+  dup compute-next-buffer-free-block
+  ~   Check whether the buffer is full. If not, do a read. If so, that's not
+  ~ an error, just clean up and take no action.
+  dup { swap sys-read
+        dup -2 =
+        { drop drop s" Read error." emitstring 0 sys-exit }
+        { swap dup buffer-logical-length @ 3roll +
+          swap buffer-logical-length ! } if-else }
+      { drop drop } if-else ;
+
+
 
 ~   Here we have some imperative code that runs immediately, to initialize
 ~ some runtime data structures.