From 128fbcf5319604dd8cd9d0dacb06b7f3d2036dfd Mon Sep 17 00:00:00 2001
From: Cat's Eye Technologies <cpressey@catseye.tc>
Date: Tue, 1 Apr 2014 23:47:10 +0100
Subject: [PATCH] lda screen, x

---
 README.markdown           |  6 +++++-
 src/SixtyPical/Emitter.hs |  3 +++
 src/SixtyPical/Parser.hs  | 23 ++++++++++++++---------
 3 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/README.markdown b/README.markdown
index 4cb7557..c0a6797 100644
--- a/README.markdown
+++ b/README.markdown
@@ -202,6 +202,7 @@ In these, `absolute` must be a `reserve`d or `locate`d address.
     
       lda #immediate
       lda absolute
+      lda absolute, x
 
       ldx #immediate
       ldx absolute
@@ -237,6 +238,7 @@ In these, `absolute` must be a `reserve`d or `locate`d address.
     X sei { block }
     
       sta absolute
+      sta absolute, x
       
       stx absolute
       
@@ -258,7 +260,7 @@ TODO
 ----
 
 *   Parse HEX values like $40A3
-*   Tables
+*   Initial values for reserved, incl. tables
 *   Character tables ("strings" to everybody else)
 *   External routines
 *   Work out the analyses again and document them
@@ -416,6 +418,7 @@ We cannot absolute-indexed a word.
     |    ldx #0
     |    ldy #255
     |    lda screen
+    |    lda screen, x
     |    inc screen
     |    tax
     |    inx
@@ -456,6 +459,7 @@ We cannot absolute-indexed a word.
     =   ldx #0
     =   ldy #255
     =   lda screen
+    =   lda screen, x
     =   inc screen
     =   tax
     =   inx
diff --git a/src/SixtyPical/Emitter.hs b/src/SixtyPical/Emitter.hs
index 30fc01a..e3708ca 100644
--- a/src/SixtyPical/Emitter.hs
+++ b/src/SixtyPical/Emitter.hs
@@ -61,6 +61,9 @@ emitInstr p r (COPY Y A) = "tya"
 emitInstr p r (COPYINDEXED A (NamedLocation label) X) = "sta " ++ label ++ ", x"
 emitInstr p r (COPYINDEXED A (NamedLocation label) Y) = "sta " ++ label ++ ", x"
 
+emitInstr p r (COPYINDEXED (NamedLocation label) A X) = "lda " ++ label ++ ", x"
+emitInstr p r (COPYINDEXED (NamedLocation label) A Y) = "lda " ++ label ++ ", x"
+
 emitInstr p r (CMP A (NamedLocation label)) = "cmp " ++ label
 emitInstr p r (CMP X (NamedLocation label)) = "cpx " ++ label
 emitInstr p r (CMP Y (NamedLocation label)) = "cpy " ++ label
diff --git a/src/SixtyPical/Parser.hs b/src/SixtyPical/Parser.hs
index 846787e..c583961 100644
--- a/src/SixtyPical/Parser.hs
+++ b/src/SixtyPical/Parser.hs
@@ -213,12 +213,20 @@ index = do
     spaces
     return X
 
+absolute_indexed :: (LocationName -> [StorageLocation] -> Instruction) -> Parser Instruction
+absolute_indexed f = do
+    l <- locationName
+    indexes <- many index
+    return $ f l indexes
+
 lda :: Parser Instruction
 lda = do
     string "lda"
     spaces
-    (try $ immediate (\v -> PUT A v) <|>
-     absolute (\l -> COPY (NamedLocation l) A))
+    (try $ immediate (\v -> PUT A v) <|> absolute_indexed gen)
+    where
+       gen l [] = COPY (NamedLocation l) A
+       gen l [X] = COPYINDEXED (NamedLocation l) A X
 
 ldx :: Parser Instruction
 ldx = do
@@ -238,13 +246,10 @@ sta :: Parser Instruction
 sta = do
     string "sta"
     spaces
-    l <- locationName
-    indexes <- many index
-    return $ case indexes of
-        [] ->
-            COPY A (NamedLocation l)
-        [X] ->
-            COPYINDEXED A (NamedLocation l) X
+    absolute_indexed gen
+    where
+       gen l [] = COPY A (NamedLocation l)
+       gen l [X] = COPYINDEXED A (NamedLocation l) X
 
 stx :: Parser Instruction
 stx = do