Indexed indirect. For a relaxing demo.

README.markdown

@@ -313,6 +313,17 @@ A comment may appear after each command.
     | }
     = True
 
+A comment may appear after each declaration.
+
+    | reserve byte lives      ; fnord
+    | assign byte gdcol 647   ; fnord
+    | external blastoff 4     ; fnnnnnnnnnnnnnnnnfffffffff
+    | 
+    | routine main {
+    |   nop
+    | }
+    = True
+
 A program may `reserve` and `assign`.
 
     | reserve byte lives
@@ -486,6 +497,7 @@ We cannot absolute-indexed a word.
     |    sta screen
     |    sta screen, x
     |    sta screen, y
+    |    sta (screen), y
     |    dec screen
     |    clc
     |    cld
@@ -530,6 +542,7 @@ We cannot absolute-indexed a word.
     =   sta screen
     =   sta screen, x
     =   sta screen, y
+    =   sta (screen), y
     =   dec screen
     =   clc
     =   cld

eg/demo.60pical

@@ -1,4 +1,4 @@
-assign byte table screen 1024
+assign byte table screen $0400
 assign byte table screen2 1274
 assign byte table screen3 1524
 assign byte table screen4 1774
@@ -14,11 +14,24 @@ assign byte table vic_bg 53281
 assign vector cinv 788
 reserve vector save_cinv
 
+; TODO: this should be a word
+
+assign byte pos_lo $fb
+assign byte pos_hi $fc
+
+reserve byte value
+
+reserve byte m_hi
+reserve byte m_lo
+reserve byte n_hi
+reserve byte n_lo
+
 routine main {
     lda #5
     sta vic_border
     lda #0
     sta vic_bg
+    jsr reset_pos
     jsr clear_screen
     sei {
         copy vector cinv to save_cinv
@@ -28,11 +41,59 @@ routine main {
     repeat bcc { }
 }
 
+routine reset_pos {
+    lda #$00
+    sta pos_lo
+    lda #$04
+    sta pos_hi
+}
+
 routine our_cinv {
-    inc screen
+    lda value
+    inc value
+    ldy #0
+    sta (pos_lo), y
+    jsr increment_pos
+    jsr compare_pos
+    if beq {
+        jsr reset_pos
+    } else {
+    }
     jmp save_cinv
 }
 
+routine increment_pos {
+    clc
+    lda pos_lo
+    adc #1
+    sta pos_lo
+    lda pos_hi
+    adc #0
+    sta pos_hi
+}
+
+routine compare_pos {
+    lda pos_lo
+    sta m_lo
+    lda pos_hi
+    sta m_hi
+    lda #$07
+    sta n_hi
+    lda #$e8
+    sta n_lo
+    jsr compare_16_bit
+}
+
+routine compare_16_bit {
+    lda m_hi
+    cmp n_hi
+    if beq {
+        lda m_lo
+        cmp n_lo
+    } else {
+    }
+}
+
 routine clear_screen {
     ldy #0
     repeat bne {

src/SixtyPical/Emitter.hs

@@ -60,6 +60,8 @@ emitInstr p r (COPYINDEXED A (NamedLocation label) Y) = "sta " ++ label ++ ", y"
 emitInstr p r (COPYINDEXED (NamedLocation label) A X) = "lda " ++ label ++ ", x"
 emitInstr p r (COPYINDEXED (NamedLocation label) A Y) = "lda " ++ label ++ ", y"
 
+emitInstr p r (COPYINDIRECTINDEXED A (NamedLocation label) Y) = "sta (" ++ label ++ "), y"
+
 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

src/SixtyPical/Model.hs

@@ -57,6 +57,7 @@ data Branch = BCC | BCS | BEQ | BMI | BNE | BPL | BVC | BVS
 data Instruction = PUT StorageLocation DataValue
                  | COPY StorageLocation StorageLocation
                  | COPYINDEXED StorageLocation StorageLocation StorageLocation
+                 | COPYINDIRECTINDEXED StorageLocation StorageLocation StorageLocation
                  | CMPIMM StorageLocation DataValue
                  | CMP StorageLocation StorageLocation
                  | ADDIMM StorageLocation DataValue

src/SixtyPical/Parser.hs

@@ -10,7 +10,7 @@ import SixtyPical.Model
 
 {-
 
-Toplevel := {Decl} {Routine}.
+Toplevel := {Decl [Comment]} {Routine}.
 Decl     := "reserve" StorageType LocationName
           | "assign" StorageType LocationName Address
           | "external" RoutineName Address.
@@ -37,10 +37,16 @@ Branch   := "bcc" | "bcs" | "beq" | "bmi" | "bne" | "bpl" | "bvc" | "bvs".
 
 toplevel :: Parser Program
 toplevel = do
-    decls <- many (try assign <|> try reserve <|> try external)
+    decls <- many decl
     routines <- many routine
     return $ Program decls routines
 
+decl :: Parser Decl
+decl = do
+    d <- (try assign <|> try reserve <|> try external)
+    optional comment
+    return d
+
 reserve :: Parser Decl
 reserve = do
     string "reserve"
@@ -126,6 +132,32 @@ index = do
         "x" -> X
         "y" -> Y
 
+data Directness = Direct LocationName
+                | Indirect LocationName
+    deriving (Ord, Show, Eq)
+
+indirect_location :: Parser Directness
+indirect_location = do
+    string "("
+    spaces
+    l <- locationName
+    string ")"
+    spaces
+    return $ Indirect l
+
+direct_location :: Parser Directness
+direct_location = do
+    l <- locationName
+    return $ Direct l
+
+directness_location = (try indirect_location) <|> direct_location
+
+indirect_indexed :: (Directness -> [StorageLocation] -> Instruction) -> Parser Instruction
+indirect_indexed f = do
+    d <- directness_location
+    indexes <- many index
+    return $ f d indexes
+
 absolute_indexed :: (LocationName -> [StorageLocation] -> Instruction) -> Parser Instruction
 absolute_indexed f = do
     l <- locationName
@@ -305,10 +337,11 @@ sta :: Parser Instruction
 sta = do
     string "sta"
     spaces
-    absolute_indexed gen
+    indirect_indexed gen
     where
-       gen l [] = COPY A (NamedLocation l)
-       gen l [reg] = COPYINDEXED A (NamedLocation l) reg
+       gen (Direct l) [] = COPY A (NamedLocation l)
+       gen (Direct l) [reg] = COPYINDEXED A (NamedLocation l) reg
+       gen (Indirect l) [reg] = COPYINDIRECTINDEXED A (NamedLocation l) reg
 
 stx :: Parser Instruction
 stx = do