From ccf3994e3b6f669d18ce83329adc1998a04923fe Mon Sep 17 00:00:00 2001
From: bbbradsmith <bbbradsmith@users.noreply.github.com>
Date: Tue, 21 Feb 2023 04:00:34 -0500
Subject: [PATCH] ca65 jsr/jmp/rts will not promote to jsl/jml/rtl by default,
 but can still be enabled with new feature long_jsr_jmp_rts

---
 doc/ca65.sgml      | 23 ++++++++++++++++--
 src/ca65/feature.c |  2 ++
 src/ca65/feature.h |  1 +
 src/ca65/global.c  |  1 +
 src/ca65/global.h  |  1 +
 src/ca65/instr.c   | 60 ++++++++++++++++++++++++++++++++++++++++------
 6 files changed, 79 insertions(+), 9 deletions(-)

diff --git a/doc/ca65.sgml b/doc/ca65.sgml
index 19fd3aa2a..276a2b697 100644
--- a/doc/ca65.sgml
+++ b/doc/ca65.sgml
@@ -183,7 +183,7 @@ Here is a description of all the command line options:
 
   Enable an emulation feature. This is identical as using <tt/.FEATURE/
   in the source with two exceptions: Feature names must be lower case, and
-  each feature must be specified by using an extra <tt/--feature/ option,
+  each feature must be specified by using a separate <tt/--feature/ option,
   comma separated lists are not allowed.
 
   See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
@@ -2825,6 +2825,23 @@ See: <tt><ref id=".ASCIIZ" name=".ASCIIZ"></tt>,<tt><ref id=".CHARMAP" name=".CH
     overridden. When using this feature, you may also get into trouble if
     later versions of the assembler define new keywords starting with a dot.
 
+  <tag><tt>long_jsr_jmp_rts</tt><label id="long_jsr_jmp_rts"></tag>
+
+    Affects 65816 mode only.
+
+    Allows <tt>jsr</tt> and <tt>jmp</tt> to produce long jumps if the target
+    address has been previously declared in a <tt>far</tt> segment,
+    or imported as <tt>far</tt>.
+    Otherwise <tt>jsl</tt> and <tt>jml</tt> must be used instead.
+
+    Also allows <tt><ref id=".SMART" name=".SMART"></tt> to convert <tt>rts</tt>
+    to a long return <tt>rtl</tt> when the enclosing scope or memory model
+    indicates returning from a <tt>far</tt> procedure.
+
+    This permits compatibility with the old behavior of this assembler, or other
+    assemblers which similarly allowed <tt>jsr</tt> and <tt>jmp</tt> to be used
+    this way.
+
   <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
 
     Accept single quotes as well as double quotes as terminators for char
@@ -3994,7 +4011,9 @@ See: <tt><ref id=".ASCIIZ" name=".ASCIIZ"></tt>,<tt><ref id=".BYTE" name=".BYTE"
         the assembler cannot trace the execution flow this may lead to false
         results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
         instructions to tell the assembler about the current settings.
-  <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
+  <item>In 65816 mode, if the <tt><ref id="long_jsr_jmp_rts"
+        name="long_jsr_jmp_rts"></tt> feature is enabled,
+        smart mode will replace a <tt/RTS/ instruction by <tt/RTL/ if it is
         used within a procedure declared as <tt/far/, or if the procedure has
         no explicit address specification, but it is <tt/far/ because of the
         memory model used.
diff --git a/src/ca65/feature.c b/src/ca65/feature.c
index b11345338..754b645cf 100644
--- a/src/ca65/feature.c
+++ b/src/ca65/feature.c
@@ -66,6 +66,7 @@ static const char* const FeatureKeys[FEAT_COUNT] = {
     "addrsize",
     "bracket_as_indirect",
     "string_escapes",
+    "long_jsr_jmp_rts",
 };
 
 
@@ -125,6 +126,7 @@ feature_t SetFeature (const StrBuf* Key)
         case FEAT_ADDRSIZE:                   AddrSize          = 1;    break;
         case FEAT_BRACKET_AS_INDIRECT:        BracketAsIndirect = 1;    break;
         case FEAT_STRING_ESCAPES:             StringEscapes     = 1;    break;
+        case FEAT_LONG_JSR_JMP_RTS:           LongJsrJmpRts     = 1;    break;
         default:                         /* Keep gcc silent */          break;
     }
 
diff --git a/src/ca65/feature.h b/src/ca65/feature.h
index 876f3c4a8..a29ee0172 100644
--- a/src/ca65/feature.h
+++ b/src/ca65/feature.h
@@ -68,6 +68,7 @@ typedef enum {
     FEAT_ADDRSIZE,
     FEAT_BRACKET_AS_INDIRECT,
     FEAT_STRING_ESCAPES,
+    FEAT_LONG_JSR_JMP_RTS,
 
     /* Special value: Number of features available */
     FEAT_COUNT
diff --git a/src/ca65/global.c b/src/ca65/global.c
index a216fc406..962f368db 100644
--- a/src/ca65/global.c
+++ b/src/ca65/global.c
@@ -67,6 +67,7 @@ unsigned char LineCont           = 0;   /* Allow line continuation */
 unsigned char LargeAlignment     = 0;   /* Don't warn about large alignments */
 unsigned char RelaxChecks        = 0;   /* Relax a few assembler checks */
 unsigned char StringEscapes      = 0;   /* Allow C-style escapes in strings */
+unsigned char LongJsrJmpRts      = 0;   /* Allow JSR/JMP/RTS as alias for JSL/JML/RTL */
 
 /* Emulation features */
 unsigned char DollarIsPC         = 0;   /* Allow the $ symbol as current PC */
diff --git a/src/ca65/global.h b/src/ca65/global.h
index 77d90beca..c92291ad3 100644
--- a/src/ca65/global.h
+++ b/src/ca65/global.h
@@ -69,6 +69,7 @@ extern unsigned char    LineCont;           /* Allow line continuation */
 extern unsigned char    LargeAlignment;     /* Don't warn about large alignments */
 extern unsigned char    RelaxChecks;        /* Relax a few assembler checks */
 extern unsigned char    StringEscapes;      /* Allow C-style escapes in strings */
+extern unsigned char    LongJsrJmpRts;      /* Allow JSR/JMP/RTS as alias for JSL/JML/RTL */
 
 /* Emulation features */
 extern unsigned char    DollarIsPC;         /* Allow the $ symbol as current PC */
diff --git a/src/ca65/instr.c b/src/ca65/instr.c
index d0d7ce64c..745072a09 100644
--- a/src/ca65/instr.c
+++ b/src/ca65/instr.c
@@ -120,9 +120,21 @@ static void PutJMP (const InsDesc* Ins);
 ** to check for this case and is otherwise identical to PutAll.
 */
 
+static void PutJMP816 (const InsDesc* Ins);
+/* Handle the JMP instruction for the 816.
+** Allowing the long_jsr_jmp_rts feature to permit a long JMP.
+** Note that JMP [abs] and JML [abs] are always both permitted for instruction $DC,
+** because the [] notation for long indirection makes the generated instruction unambiguous.
+*/
+
+static void PutJSR816 (const InsDesc* Ins);
+/* Handle the JSR instruction for the 816.
+** Allowing the long_jsr_jmp_rts feature to permit a long JSR.
+*/
+
 static void PutRTS (const InsDesc* Ins attribute ((unused)));
 /* Handle the RTS instruction for the 816. In smart mode emit a RTL opcode if
-** the enclosing scope is FAR.
+** the enclosing scope is FAR, but only if the long_jsr_jmp_rts feature applies.
 */
 
 static void PutAll (const InsDesc* Ins);
@@ -758,9 +770,9 @@ static const struct {
         { "INX",  0x0000001, 0xe8, 0, PutAll },
         { "INY",  0x0000001, 0xc8, 0, PutAll },
         { "JML",  0x4000010, 0x5c, 1, PutAll },
-        { "JMP",  0x4010818, 0x4c, 6, PutAll },
+        { "JMP",  0x4010818, 0x4c, 6, PutJMP816 },
         { "JSL",  0x0000010, 0x20, 7, PutAll },
-        { "JSR",  0x0010018, 0x20, 7, PutAll },
+        { "JSR",  0x0010018, 0x20, 7, PutJSR816 },
         { "LDA",  0x0b8f6fc, 0xa0, 0, PutAll },
         { "LDX",  0x0c0030c, 0xa2, 1, PutAll },
         { "LDY",  0x0c0006c, 0xa0, 1, PutAll },
@@ -1627,12 +1639,46 @@ static void PutJMP (const InsDesc* Ins)
 
 
 
-static void PutRTS (const InsDesc* Ins attribute ((unused)))
-/* Handle the RTS instruction for the 816. In smart mode emit a RTL opcode if
-** the enclosing scope is FAR.
+static void PutJMP816 (const InsDesc* Ins)
+/* Handle the JMP instruction for the 816.
+** Allowing the long_jsr_jmp_rts feature to permit a long JMP.
+** Note that JMP [abs] and JML [abs] are always both permitted for instruction $DC,
+** because the [] notation for long indirection makes the generated instruction unambiguous.
 */
 {
-    if (SmartMode && CurrentScope->AddrSize == ADDR_SIZE_FAR) {
+    if (LongJsrJmpRts) {
+        PutJMP (Ins);
+    } else {
+        InsDesc InsAbs = *Ins;
+        InsAbs.AddrMode &= ~(AM65_ABS_LONG);
+        PutJMP (&InsAbs);
+    }
+}
+
+
+
+static void PutJSR816 (const InsDesc* Ins)
+/* Handle the JSR instruction for the 816.
+** Allowing the long_jsr_jmp_rts feature to permit a long JSR.
+*/
+{
+    if (LongJsrJmpRts) {
+        PutAll (Ins);
+    } else {
+        InsDesc InsAbs = *Ins;
+        InsAbs.AddrMode &= ~(AM65_ABS_LONG);
+        PutJMP (&InsAbs);
+    }
+}
+
+
+
+static void PutRTS (const InsDesc* Ins attribute ((unused)))
+/* Handle the RTS instruction for the 816. In smart mode emit a RTL opcode if
+** the enclosing scope is FAR, but only if the long_jsr_jmp_rts feature applies.
+*/
+{
+    if (LongJsrJmpRts && SmartMode && CurrentScope->AddrSize == ADDR_SIZE_FAR) {
         Emit0 (0x6B);       /* RTL */
     } else {
         Emit0 (0x60);       /* RTS */