From da150aeeac5e030d34a208bf3efabdaaac23e81b Mon Sep 17 00:00:00 2001
From: bbbradsmith <bbbradsmith@users.noreply.github.com>
Date: Fri, 24 Feb 2023 18:00:58 -0500
Subject: [PATCH] allow .feature to both enable and disable

---
 doc/ca65.sgml      | 14 ++++++++-----
 src/ca65/feature.c | 50 +++++++++++++++++++---------------------------
 src/ca65/feature.h |  6 ++----
 src/ca65/main.c    | 11 ++++++----
 src/ca65/pseudo.c  | 25 +++++++++++++++--------
 5 files changed, 56 insertions(+), 50 deletions(-)

diff --git a/doc/ca65.sgml b/doc/ca65.sgml
index b65d337bb..02ed5ad8a 100644
--- a/doc/ca65.sgml
+++ b/doc/ca65.sgml
@@ -2746,15 +2746,19 @@ See: <tt><ref id=".ASCIIZ" name=".ASCIIZ"></tt>,<tt><ref id=".CHARMAP" name=".CH
   This directive may be used to enable one or more compatibility features
   of the assembler. While the use of <tt/.FEATURE/ should be avoided when
   possible, it may be useful when porting sources written for other
-  assemblers. There is no way to switch a feature off, once you have
-  enabled it, so using
+  assemblers. After the feature name an optional '+' or '-' may specify whether
+  to enable or disable the feature (enable if omitted). Multiple features may be
+  enabled, separated by commas. Examples:
 
   <tscreen><verb>
-        .FEATURE        xxx
+        ; enable c_comments
+        .feature   c_comments
+        .feature   c_comments +
+        ; enable force_range, disable underline_in_numbers, enable labels_without_colons
+        .feature   force_range, underline_in_numbers -, labels_without_colons +
+        .feature   force_range +, underline_in_numbers off, labels_without_colons on
   </verb></tscreen>
 
-  will enable the feature until end of assembly is reached.
-
   The following features are available:
 
   <descrip>
diff --git a/src/ca65/feature.c b/src/ca65/feature.c
index 754b645cf..41177d66b 100644
--- a/src/ca65/feature.c
+++ b/src/ca65/feature.c
@@ -98,38 +98,30 @@ feature_t FindFeature (const StrBuf* Key)
 
 
 
-feature_t SetFeature (const StrBuf* Key)
-/* Find the feature and set the corresponding flag if the feature is known.
-** In any case, return the feature found. An invalid Key will return
-** FEAT_UNKNOWN.
+void SetFeature (feature_t Feature, unsigned char On)
+/* Set the corresponding feature flag if Feature is valid.
 */
 {
-    /* Map the string to an enum value */
-    feature_t Feature = FindFeature (Key);
-
     /* Set the flags */
     switch (Feature) {
-        case FEAT_DOLLAR_IS_PC:               DollarIsPC        = 1;    break;
-        case FEAT_LABELS_WITHOUT_COLONS:      NoColonLabels     = 1;    break;
-        case FEAT_LOOSE_STRING_TERM:          LooseStringTerm   = 1;    break;
-        case FEAT_LOOSE_CHAR_TERM:            LooseCharTerm     = 1;    break;
-        case FEAT_AT_IN_IDENTIFIERS:          AtInIdents        = 1;    break;
-        case FEAT_DOLLAR_IN_IDENTIFIERS:      DollarInIdents    = 1;    break;
-        case FEAT_LEADING_DOT_IN_IDENTIFIERS: LeadingDotInIdents= 1;    break;
-        case FEAT_ORG_PER_SEG:                OrgPerSeg         = 1;    break;
-        case FEAT_PC_ASSIGNMENT:              PCAssignment      = 1;    break;
-        case FEAT_MISSING_CHAR_TERM:          MissingCharTerm   = 1;    break;
-        case FEAT_UBIQUITOUS_IDENTS:          UbiquitousIdents  = 1;    break;
-        case FEAT_C_COMMENTS:                 CComments         = 1;    break;
-        case FEAT_FORCE_RANGE:                ForceRange        = 1;    break;
-        case FEAT_UNDERLINE_IN_NUMBERS:       UnderlineInNumbers= 1;    break;
-        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;
+        case FEAT_DOLLAR_IS_PC:               DollarIsPC        = On;    break;
+        case FEAT_LABELS_WITHOUT_COLONS:      NoColonLabels     = On;    break;
+        case FEAT_LOOSE_STRING_TERM:          LooseStringTerm   = On;    break;
+        case FEAT_LOOSE_CHAR_TERM:            LooseCharTerm     = On;    break;
+        case FEAT_AT_IN_IDENTIFIERS:          AtInIdents        = On;    break;
+        case FEAT_DOLLAR_IN_IDENTIFIERS:      DollarInIdents    = On;    break;
+        case FEAT_LEADING_DOT_IN_IDENTIFIERS: LeadingDotInIdents= On;    break;
+        case FEAT_ORG_PER_SEG:                OrgPerSeg         = On;    break;
+        case FEAT_PC_ASSIGNMENT:              PCAssignment      = On;    break;
+        case FEAT_MISSING_CHAR_TERM:          MissingCharTerm   = On;    break;
+        case FEAT_UBIQUITOUS_IDENTS:          UbiquitousIdents  = On;    break;
+        case FEAT_C_COMMENTS:                 CComments         = On;    break;
+        case FEAT_FORCE_RANGE:                ForceRange        = On;    break;
+        case FEAT_UNDERLINE_IN_NUMBERS:       UnderlineInNumbers= On;    break;
+        case FEAT_ADDRSIZE:                   AddrSize          = On;    break;
+        case FEAT_BRACKET_AS_INDIRECT:        BracketAsIndirect = On;    break;
+        case FEAT_STRING_ESCAPES:             StringEscapes     = On;    break;
+        case FEAT_LONG_JSR_JMP_RTS:           LongJsrJmpRts     = On;    break;
+        default:                                                         break;
     }
-
-    /* Return the value found */
-    return Feature;
 }
diff --git a/src/ca65/feature.h b/src/ca65/feature.h
index a29ee0172..8eeb62e6f 100644
--- a/src/ca65/feature.h
+++ b/src/ca65/feature.h
@@ -87,10 +87,8 @@ feature_t FindFeature (const StrBuf* Key);
 ** feature is invalid, return FEAT_UNKNOWN.
 */
 
-feature_t SetFeature (const StrBuf* Key);
-/* Find the feature and set the corresponding flag if the feature is known.
-** In any case, return the feature found. An invalid Key will return
-** FEAT_UNKNOWN.
+void SetFeature (feature_t Feature, unsigned char On);
+/* Set the corresponding feature flag if Feature is valid.
 */
 
 
diff --git a/src/ca65/main.c b/src/ca65/main.c
index 9710924bf..7183ff046 100644
--- a/src/ca65/main.c
+++ b/src/ca65/main.c
@@ -489,12 +489,15 @@ static void OptDebugInfo (const char* Opt attribute ((unused)),
 static void OptFeature (const char* Opt attribute ((unused)), const char* Arg)
 /* Set an emulation feature */
 {
-    /* Make a string buffer from Arg */
-    StrBuf Feature;
+    /* Make a string buffer from Arg and use it to find the feature. */
+    StrBuf StrFeature;
+    feature_t Feature = FindFeature (SB_InitFromString (&StrFeature, Arg));
 
-    /* Set the feature, check for errors */
-    if (SetFeature (SB_InitFromString (&Feature, Arg)) == FEAT_UNKNOWN) {
+    /* Enable the feature, check for errors */
+    if (Feature == FEAT_UNKNOWN) {
         AbEnd ("Illegal emulation feature: '%s'", Arg);
+    } else {
+        SetFeature (Feature, 1);
     }
 }
 
diff --git a/src/ca65/pseudo.c b/src/ca65/pseudo.c
index 843f5b9d2..1877512d5 100644
--- a/src/ca65/pseudo.c
+++ b/src/ca65/pseudo.c
@@ -1023,7 +1023,10 @@ static void DoFatal (void)
 static void DoFeature (void)
 /* Switch the Feature option */
 {
-    /* Allow a list of comma separated keywords */
+    feature_t Feature;
+    unsigned char On;
+
+    /* Allow a list of comma separated feature keywords with optional +/- or ON/OFF */
     while (1) {
 
         /* We expect an identifier */
@@ -1034,18 +1037,24 @@ static void DoFeature (void)
 
         /* Make the string attribute lower case */
         LocaseSVal ();
-
-        /* Set the feature and check for errors */
-        if (SetFeature (&CurTok.SVal) == FEAT_UNKNOWN) {
+        Feature = FindFeature(&CurTok.SVal);
+        if (Feature == FEAT_UNKNOWN) {
             /* Not found */
             ErrorSkip ("Invalid feature: '%m%p'", &CurTok.SVal);
             return;
-        } else {
-            /* Skip the keyword */
-            NextTok ();
+        }
+        NextTok ();
+
+        /* Optional +/- or ON/OFF */
+        On = 1;
+        if (CurTok.Tok != TOK_COMMA && !TokIsSep (CurTok.Tok)) {
+            SetBoolOption(&On);
         }
 
-        /* Allow more than one keyword */
+        /* Apply feature setting. */
+        SetFeature (Feature, On);
+
+        /* Allow more than one feature separated by commas. */
         if (CurTok.Tok == TOK_COMMA) {
             NextTok ();
         } else {