From ebe53f540c8f8fe8e42a8b63480c0a5fb67ce94b Mon Sep 17 00:00:00 2001
From: Chris Pressey <cpressey@catseye.tc>
Date: Thu, 29 Mar 2018 11:46:56 +0100
Subject: [PATCH] Fix bug when zero page address was $00.

---
 eg/atari2600/atari-2600-example.60p |  2 +-
 eg/atari2600/build.sh               |  1 +
 src/sixtypical/compiler.py          |  2 +-
 tests/SixtyPical Compilation.md     | 11 ++++++++---
 4 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/eg/atari2600/atari-2600-example.60p b/eg/atari2600/atari-2600-example.60p
index 59d8179..fad76c3 100644
--- a/eg/atari2600/atari-2600-example.60p
+++ b/eg/atari2600/atari-2600-example.60p
@@ -26,7 +26,7 @@ byte colour @ $80
 byte luminosity @ $81
 byte joystick_delay @ $82
 
-byte table[8] image_data : "ZZZZUUUU"   // [126, 129, 153, 165, 129, 165, 129, 126]
+byte table[8] image_data : 126, 129, 153, 165, 129, 165, 129, 126
         // %01111110 
         // %10000001
         // %10011001
diff --git a/eg/atari2600/build.sh b/eg/atari2600/build.sh
index 1f141c1..1cb7509 100755
--- a/eg/atari2600/build.sh
+++ b/eg/atari2600/build.sh
@@ -6,4 +6,5 @@ if [ "x$COMPARE" != "x" ]; then
   dcc6502 -o 0xf000 -m 200 atari-2600-example.bin > atari-2600-example.bin.disasm.txt
   dcc6502 -o 0xf000 -m 200 atari-2600-example-60p.bin > atari-2600-example-60p.bin.disasm.txt
   paste atari-2600-example.bin.disasm.txt atari-2600-example-60p.bin.disasm.txt | pr -t -e24
+  #diff -ru atari-2600-example.bin.disasm.txt atari-2600-example-60p.bin.disasm.txt
 fi
diff --git a/src/sixtypical/compiler.py b/src/sixtypical/compiler.py
index add19e9..7dedbd4 100644
--- a/src/sixtypical/compiler.py
+++ b/src/sixtypical/compiler.py
@@ -68,7 +68,7 @@ class Compiler(object):
         return self.labels[name]
 
     def absolute_or_zero_page(self, label):
-        if label.addr and label.addr < 256:
+        if label.addr is not None and label.addr < 256:
             return ZeroPage(label)
         else:
             return Absolute(label)
diff --git a/tests/SixtyPical Compilation.md b/tests/SixtyPical Compilation.md
index 511ed5c..629237d 100644
--- a/tests/SixtyPical Compilation.md	
+++ b/tests/SixtyPical Compilation.md	
@@ -114,19 +114,24 @@ Memory location with explicit address.
 
 Accesses to memory locations in zero-page with `ld` and `st` use zero-page addressing.
 
+    | byte zp @ $00
     | byte screen @ 100
     | 
     | routine main
-    |   inputs screen
-    |   outputs screen
+    |   inputs screen, zp
+    |   outputs screen, zp
     |   trashes a, z, n
     | {
     |   ld a, screen
     |   st a, screen
+    |   ld a, zp
+    |   st a, zp
     | }
     = $080D   LDA $64
     = $080F   STA $64
-    = $0811   RTS
+    = $0811   LDA $00
+    = $0813   STA $00
+    = $0815   RTS
 
 Memory location with initial value.