Beginnings of rework on the analyzer.

README.markdown

@@ -50,7 +50,7 @@ certain ways.  For example, these are illegal:
 ### Abstract Interpretation ###
 
 SixtyPical tries to prevent the program from using data that has no meaning.
-For example, the following is illegal:
+For example, the following:
 
     routine do_it {
         lda #0
@@ -58,7 +58,7 @@ For example, the following is illegal:
         sta vic_border_colour    ; uh... what do we know about reg A here?
     }
 
-...*unless* one of the following is true:
+...is illegal *unless* one of the following is true:
 
 *   the A register is declared to be a meaningful output of `update_score`
 *   `update_score` was determined to not change the value of the A register
@@ -183,4 +183,4 @@ TODO
 *   `jsr (vector)`
 *   `jmp routine`
 *   insist on EOL after each instruction.  need spacesWOEOL production
-*   `copy immediate word`
+*   asl .a

doc/Analyzing.markdown

@@ -0,0 +1,41 @@
+Anayzling SixtyPical Programs
+=============================
+
+    -> Tests for functionality "Analyze SixtyPical program"
+    
+    -> Functionality "Analyze SixtyPical program" is implemented by
+    -> shell command "bin/sixtypical analyze %(test-file)"
+
+A routine cannot expect registers which a called routine does not
+preserve, to be preserved.
+
+    | assign byte border_colour 4000
+    | reserve byte score
+    | routine update_score
+    | {
+    |   lda #8
+    |   sta score
+    | }
+    | routine main {
+    |   lda #4
+    |   jsr update_score
+    |   sta border_colour
+    | }
+    ? routine does not preserve register
+
+But if it does it can.
+
+    | assign byte border_colour 4000
+    | reserve byte score
+    | routine update_score
+    | {
+    |   ldx score
+    |   inx
+    |   stx score
+    | }
+    | routine main {
+    |   lda #4
+    |   jsr update_score
+    |   sta border_colour
+    | }
+    = True

src/SixtyPical/Analyzer.hs

@@ -84,3 +84,7 @@ checkInstr (REPEAT _ branch blk) progCtx routCtx =
     routCtx
 checkInstr NOP progCtx routCtx =
     routCtx
+
+checkInstr instr _ _ = error (
+    "Internal error: sixtypical doesn't know how to " ++
+    "analyze '" ++ (show instr) ++ "'")

test.sh

@@ -1,4 +1,7 @@
 #!/bin/sh
 
-FILES="doc/Checking.markdown doc/Emitting.markdown doc/Instruction_Support.markdown"
+FILES="doc/Checking.markdown
+       doc/Emitting.markdown
+       doc/Instruction_Support.markdown
+       doc/Analyzing.markdown"
 ./build.sh && falderal --substring-error ${FILES}