From d77ecba5180473f084ebbe08be4980d5dfa2c51f Mon Sep 17 00:00:00 2001
From: Karol Stasiak <karol.m.stasiak@gmail.com>
Date: Fri, 31 Jul 2020 16:07:10 +0200
Subject: [PATCH] CoCo: encconv support

---
 docs/lang/text.md                             |  1 +
 docs/stdlib/encconv.md                        | 16 ++++++
 include/encconv.mfk                           | 54 +++++++++++++++++--
 include/platform/coco_rsdos.ini               |  1 -
 src/main/scala/millfork/Platform.scala        |  2 +
 .../parser/AbstractSourceLoadingQueue.scala   |  3 ++
 6 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/docs/lang/text.md b/docs/lang/text.md
index b5c69af7..7f33b52b 100644
--- a/docs/lang/text.md
+++ b/docs/lang/text.md
@@ -151,6 +151,7 @@ The exact value of `{nullchar}` is encoding-dependent:
     * in the `petscr` and `petscrjp` encodings it's `{xe0}`,
     * in the `atasciiscr` encoding it's `{xdb}`,
     * in the `pokemon1*` encodings it's `{x50}`,
+    * in the `cocoscr` encoding it's exceptionally two bytes: `{xd0}`
     * in the `utf16be` and `utf16le` encodings it's exceptionally two bytes: `{x00}{x00}`
     * in other encodings it's `{x00}` (this may be a subject to change in future versions).
 
diff --git a/docs/stdlib/encconv.md b/docs/stdlib/encconv.md
index c0024902..63e54705 100644
--- a/docs/stdlib/encconv.md
+++ b/docs/stdlib/encconv.md
@@ -31,6 +31,8 @@ Available only if one of the following is true:
 
 * the default encoding is `atascii`, the screen encoding is `atasciiscr`, and the platform is 6502-based
 
+* the default encoding is `coco`, the screen encoding is `cococsr`, and the platform is 6809-based
+
 You can test for the availability of this function using the `ENCCONV_SUPPORTED` preprocessor feature.
 
 #### byte from_screencode(byte)
@@ -98,3 +100,17 @@ Reverse characters are interpreted as non-reverse characters.
 
 Available only on 6502-based platforms.
 
+#### byte coco_to_cocoscr(byte)
+
+Converts a byte from Color Computer pseudo-ASCII to a Color Computer screencode.  
+Control characters <$20 are converted inverted punctuation.
+
+Available only on 6809-based platforms.
+
+#### byte cocoscr_to_coco(byte)
+
+Converts a byte from a Color Computer screencode to Color Computer pseudo-ASCII.  
+Inverted punctuation is converted to control characters.
+
+Available only on 6809-based platforms.
+
diff --git a/include/encconv.mfk b/include/encconv.mfk
index aa627f75..82ddd0a2 100644
--- a/include/encconv.mfk
+++ b/include/encconv.mfk
@@ -83,6 +83,8 @@ void strz_to_screencode(pointer p) {
     }
 }
 
+#endif
+
 void pstr_from_screencode(pointer p) {
     byte i, l
     l = p[0]
@@ -98,8 +100,6 @@ void pstr_to_screencode(pointer p) {
     }
 }
 
-#endif
-
 #endif // ENCODING_SAME/ENCCONV_SUPPORTED
 
 
@@ -199,4 +199,52 @@ __atascii_to_atasciiscr_end:
     rts
 }
 
-#endif
\ No newline at end of file
+#endif
+
+#if ARCH_6809
+
+asm byte coco_to_cocoscr(byte register(b) char) {
+    cmpb #$20
+    bcc __coco_to_cocoscr_40
+    eorb #$20
+    rts
+__coco_to_cocoscr_40:
+    cmpb #$40
+    bcc __coco_to_cocoscr_60
+    eorb #$40
+    rts
+__coco_to_cocoscr_60:
+    cmpb #$60
+    bcc __coco_to_cocoscr_80
+    rts
+__coco_to_cocoscr_80:
+    cmpb #$80
+    bcc __coco_to_cocoscr_end
+    eorb #$60
+__coco_to_cocoscr_end:
+    rts
+}
+
+asm byte cocoscr_to_coco(byte register(b) char) {
+    cmpb #$20
+    bcc __cocoscr_to_coco_40
+    eorb #$60
+    rts
+__cocoscr_to_coco_40:
+    cmpb #$40
+    bcc __cocoscr_to_coco_60
+    eorb #$20
+    rts
+__cocoscr_to_coco_60:
+    cmpb #$60
+    bcc __cocoscr_to_coco_80
+    rts
+__cocoscr_to_coco_80:
+    cmpb #$80
+    bcc __coco_to_cocoscr_end
+    eorb #$40
+__cocoscr_to_coco_end:
+    rts
+}
+
+#endif
diff --git a/include/platform/coco_rsdos.ini b/include/platform/coco_rsdos.ini
index 40ae103a..4e5eec74 100644
--- a/include/platform/coco_rsdos.ini
+++ b/include/platform/coco_rsdos.ini
@@ -2,7 +2,6 @@
 ; VERY EXPERIMENTAL
 [compilation]
 arch=6809
-; todo: is it ascii?
 encoding=coco
 screen_encoding=cocoscr
 modules=default_panic,stdlib,coco/kernal
diff --git a/src/main/scala/millfork/Platform.scala b/src/main/scala/millfork/Platform.scala
index 163d29b7..0aeeb1f0 100644
--- a/src/main/scala/millfork/Platform.scala
+++ b/src/main/scala/millfork/Platform.scala
@@ -329,6 +329,8 @@ object Platform {
              ("PETSCII-JP", "CBM-Screen-JP") |
              ("ATASCII", "ATASCII-Screen") =>
           CpuFamily.forType(cpu) == CpuFamily.M6502
+        case ("Color-Computer", "Color-Computer-Screen") =>
+          CpuFamily.forType(cpu) == CpuFamily.M6809
         case _ => codec.name == srcCodec.name
       }),
       "NULLCHAR_SAME" -> toLong(codec.stringTerminator == srcCodec.stringTerminator)
diff --git a/src/main/scala/millfork/parser/AbstractSourceLoadingQueue.scala b/src/main/scala/millfork/parser/AbstractSourceLoadingQueue.scala
index 35b54eb4..66c1b0bf 100644
--- a/src/main/scala/millfork/parser/AbstractSourceLoadingQueue.scala
+++ b/src/main/scala/millfork/parser/AbstractSourceLoadingQueue.scala
@@ -33,6 +33,9 @@ abstract class AbstractSourceLoadingQueue[T](val initialFilenames: List[String],
       case ("ATASCII", "ATASCII-Screen") =>
         List(AliasDefinitionStatement("__from_screencode", "atasciiscr_to_atascii", important = false),
           AliasDefinitionStatement("__to_screencode", "atascii_to_atasciiscr", important = false))
+      case ("Color-Computer", "Color-Computer-Screen") =>
+        List(AliasDefinitionStatement("__from_screencode", "cocoscr_to_coco", important = false),
+          AliasDefinitionStatement("__to_screencode", "coco_to_cocoscr", important = false))
       case _ => Nil
     }
     encodingConversionAliases