From 97d00637d277fe7c6900699fe7c7014da2493439 Mon Sep 17 00:00:00 2001
From: Chris Pressey <cpressey@catseye.tc>
Date: Thu, 7 Dec 2017 11:31:46 +0000
Subject: [PATCH] Initial work on adding 16-bit constants to a 16-bit location.

---
 src/sixtypical/analyzer.py   | 14 +++++++++++--
 tests/SixtyPical Analysis.md | 39 ++++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/src/sixtypical/analyzer.py b/src/sixtypical/analyzer.py
index 4a2b522..f74c318 100644
--- a/src/sixtypical/analyzer.py
+++ b/src/sixtypical/analyzer.py
@@ -2,7 +2,7 @@
 
 from sixtypical.ast import Program, Routine, Block, Instr
 from sixtypical.model import (
-    TYPE_BYTE, TYPE_BYTE_TABLE, BufferType, PointerType, VectorType, ExecutableType,
+    TYPE_BYTE, TYPE_WORD, TYPE_BYTE_TABLE, BufferType, PointerType, VectorType, ExecutableType,
     ConstantRef, LocationRef, IndirectRef, AddressRef,
     REG_A, REG_Y, FLAG_Z, FLAG_N, FLAG_V, FLAG_C
 )
@@ -233,7 +233,17 @@ class Analyzer(object):
                 )
             context.assert_meaningful(src)
             context.set_written(dest)
-        elif opcode in ('add', 'sub'):
+        elif opcode == 'add':
+            if src.type == TYPE_BYTE:
+                self.assert_type(TYPE_BYTE, src, dest)
+                context.assert_meaningful(src, dest, FLAG_C)
+                context.set_written(dest, FLAG_Z, FLAG_N, FLAG_C, FLAG_V)
+            else:
+                self.assert_type(TYPE_WORD, src, dest)
+                context.assert_meaningful(src, dest, FLAG_C)
+                context.set_written(dest, FLAG_Z, FLAG_N, FLAG_C, FLAG_V)
+                context.set_unmeaningful(REG_A)
+        elif opcode == 'sub':
             self.assert_type(TYPE_BYTE, src, dest)
             context.assert_meaningful(src, dest, FLAG_C)
             context.set_written(dest, FLAG_Z, FLAG_N, FLAG_C, FLAG_V)
diff --git a/tests/SixtyPical Analysis.md b/tests/SixtyPical Analysis.md
index c07db8a..9e7c753 100644
--- a/tests/SixtyPical Analysis.md	
+++ b/tests/SixtyPical Analysis.md	
@@ -373,6 +373,45 @@ Can't `add` to a memory location that isn't writeable.
     | }
     ? ForbiddenWriteError: a in main
 
+You can `add` a word constant to a word memory location.
+
+    | word score
+    | routine main
+    |   inputs a, score
+    |   outputs score
+    |   trashes a, c, z, v, n
+    | {
+    |     st off, c
+    |     add score, 1999
+    | }
+    = ok
+
+`add`ing a word constant to a word memory location trashes `a`.
+
+    | word score
+    | routine main
+    |   inputs a, score
+    |   outputs score, a
+    |   trashes c, z, v, n
+    | {
+    |     st off, c
+    |     add score, 1999
+    | }
+    ? UnmeaningfulOutputError: a in main
+
+Not sure why this doesn't also raise an error?  `a` is trashed...
+
+    | word score
+    | routine main
+    |   inputs score
+    |   outputs score
+    |   trashes c, z, v, n
+    | {
+    |     st off, c
+    |     add score, 1999
+    | }
+    ? UnmeaningfulOutputError: a in main
+
 ### sub ###
 
 Can't `sub` from or to a memory location that isn't initialized.