From c95c9c27496ba0302203f29ec5597c491dddf543 Mon Sep 17 00:00:00 2001
From: Lauri Kasanen <cand@gmx.com>
Date: Thu, 27 Oct 2022 18:19:44 +0300
Subject: [PATCH] Allow specifying range end as a size

---
 doc/da65.sgml       |  3 ++-
 src/da65/infofile.c | 16 +++++++++++++---
 src/da65/scanner.c  |  8 ++++++++
 src/da65/scanner.h  |  1 +
 4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/doc/da65.sgml b/doc/da65.sgml
index bf074a667..185dbe0e6 100644
--- a/doc/da65.sgml
+++ b/doc/da65.sgml
@@ -461,7 +461,8 @@ following attributes are recognized:
   <tag><tt>END</tt></tag>
   This gives the end address of the range. The end address is inclusive, that
   means, it is part of the range. Of course, it may not be smaller than the
-  start address.
+  start address. Optionally, the end may be given as a decimal offset instead
+  of an absolute address, "+3", to specify it as a size.
 
   <tag><tt>NAME</tt></tag>
   This is a convenience attribute. It takes a string argument and will cause
diff --git a/src/da65/infofile.c b/src/da65/infofile.c
index 6db82cb36..48a95c9b0 100644
--- a/src/da65/infofile.c
+++ b/src/da65/infofile.c
@@ -592,9 +592,19 @@ static void RangeSection (void)
             case INFOTOK_END:
                 AddAttr ("END", &Attributes, tEnd);
                 InfoNextTok ();
-                InfoAssureInt ();
-                InfoRangeCheck (0x0000, 0xFFFF);
-                End = InfoIVal;
+
+                if (InfoTok == INFOTOK_OFFSET_INTCON) {
+                    InfoRangeCheck (0x0000, 0xFFFF);
+                    if (!(Attributes & tStart))
+                        InfoError ("When using End with an offset, Start must be specified before");
+                    End = Start + InfoIVal - 1;
+                    if (End > 0xFFFF)
+                        InfoError ("Range error");
+                } else {
+                    InfoAssureInt ();
+                    InfoRangeCheck (0x0000, 0xFFFF);
+                    End = InfoIVal;
+                }
                 InfoNextTok ();
                 break;
 
diff --git a/src/da65/scanner.c b/src/da65/scanner.c
index 33fb3a826..d0301c08a 100644
--- a/src/da65/scanner.c
+++ b/src/da65/scanner.c
@@ -372,6 +372,14 @@ Again:
         return;
     }
 
+    /* Decimal number offset? */
+    if (C == '+') {
+        NextChar ();
+        InfoIVal = GetDecimalToken ();
+        InfoTok = INFOTOK_OFFSET_INTCON;
+        return;
+    }
+
     /* Other characters */
     switch (C) {
 
diff --git a/src/da65/scanner.h b/src/da65/scanner.h
index d4e38177b..63d3273f6 100644
--- a/src/da65/scanner.h
+++ b/src/da65/scanner.h
@@ -48,6 +48,7 @@
 typedef enum token_t {
     INFOTOK_NONE,
     INFOTOK_INTCON,
+    INFOTOK_OFFSET_INTCON,
     INFOTOK_STRCON,
     INFOTOK_CHARCON,
     INFOTOK_IDENT,