From 01223073992f51481b160e339af0edb09a1ac7bb Mon Sep 17 00:00:00 2001
From: Colin Leroy-Mira <colin@colino.net>
Date: Wed, 28 May 2025 08:40:51 +0200
Subject: [PATCH] Apple2: Dynamic IIe check on a2_lo_tgi

---
 doc/funcref.sgml          |  5 ++---
 include/apple2.h          |  3 +++
 include/apple2enh.h       | 11 -----------
 libsrc/apple2/tgi/a2.lo.s | 26 ++++++++++++++++++++++----
 libsrc/apple2/waitvsync.s | 23 +++++++++--------------
 5 files changed, 36 insertions(+), 32 deletions(-)

diff --git a/doc/funcref.sgml b/doc/funcref.sgml
index a235eb2e0..5eab5adcd 100644
--- a/doc/funcref.sgml
+++ b/doc/funcref.sgml
@@ -8526,11 +8526,10 @@ if the mode is not supported due to lack of hardware.
 <ref id="pce.h" name="pce.h">/
 <tag/Declaration/
 <tt>void waitvsync (void);</tt><newline>
-<tt>signed char waitvsync (void); /* For Apple II */</tt><newline>
 <tag/Description/Wait for vertical sync, to reduce flickering.
 <tag/Notes/<itemize>
-<item>The function will return -1 when the feature is not supported,
-like on the Apple&nbsp;&rsqb;&lsqb;+.
+<item>The function will silently fail when the feature is not
+supported, like on the Apple&nbsp;&rsqb;&lsqb;+.
 </itemize>
 <tag/Availability/Platforms served by the headers above
 (Atmos requires the VSync hack)
diff --git a/include/apple2.h b/include/apple2.h
index 430a3e1b1..82f8dd3e4 100644
--- a/include/apple2.h
+++ b/include/apple2.h
@@ -343,6 +343,9 @@ signed char __fastcall__ videomode (unsigned mode);
 ** installed. Call with one of the VIDEOMODE_xx constants.
 */
 
+void waitvsync (void);
+/* Wait for start of next frame */
+
 
 
 /* End of apple2.h */
diff --git a/include/apple2enh.h b/include/apple2enh.h
index 8c463fccf..84e6f4ab3 100644
--- a/include/apple2enh.h
+++ b/include/apple2enh.h
@@ -63,16 +63,5 @@ extern void a2e_lo_tgi[];
 
 
 
-/*****************************************************************************/
-/*                                   Code                                    */
-/*****************************************************************************/
-
-
-
-void waitvsync (void);
-/* Wait for start of next frame */
-
-
-
 /* End of apple2enh.h */
 #endif
diff --git a/libsrc/apple2/tgi/a2.lo.s b/libsrc/apple2/tgi/a2.lo.s
index 8b00c5d20..b0f608e86 100644
--- a/libsrc/apple2/tgi/a2.lo.s
+++ b/libsrc/apple2/tgi/a2.lo.s
@@ -53,7 +53,7 @@ Y2      :=      ptr4
 
         .byte   $74, $67, $69   ; "tgi"
         .byte   TGI_API_VERSION ; TGI API version number
-        .addr   $0000           ; Library reference
+libref: .addr   $0000           ; Library reference
         .word   40              ; X resolution
         .word   48              ; Y resolution
         .byte   16              ; Number of drawing colors
@@ -93,6 +93,10 @@ Y2      :=      ptr4
 ERROR:  .res    1               ; Error code
 MIX:    .res    1               ; 4 lines of text
 
+.ifndef __APPLE2ENH__
+machinetype: .res 1
+.endif
+
 ; ------------------------------------------------------------------------
 
         .rodata
@@ -126,11 +130,15 @@ INIT:
         bit     $C082           ; Switch in ROM
         jsr     SETGR
         bit     MIXCLR
-        .ifdef  __APPLE2ENH__
+
+        .ifndef  __APPLE2ENH__
+        bit     machinetype
+        bpl     lc_in
+        .endif
+
         sta     IOUDISON
         bit     DHIRESOFF
-        .endif
-        bit     $C080           ; Switch in LC bank 2 for R/O
+lc_in:  bit     $C080           ; Switch in LC bank 2 for R/O
 
         ; Done, reset the error code
         lda     #TGI_ERR_OK
@@ -144,6 +152,16 @@ INIT:
 ; most of the time.
 ; Must set an error code: NO
 INSTALL:
+        .ifndef __APPLE2ENH__
+        lda     libref
+        ldx     libref+1
+        sta     ptr1
+        stx     ptr1+1
+        ldy     #$0
+        lda     (ptr1),y
+        sta     machinetype
+        bpl     :+
+        .endif
         ; Fall through
 
 ; UNINSTALL routine. Is called before the driver is removed from memory. May
diff --git a/libsrc/apple2/waitvsync.s b/libsrc/apple2/waitvsync.s
index e03796ad9..d02071915 100644
--- a/libsrc/apple2/waitvsync.s
+++ b/libsrc/apple2/waitvsync.s
@@ -13,31 +13,28 @@
         .include        "apple2.inc"
 
 _waitvsync:
+        .ifndef  __APPLE2ENH__
+        bit     machinetype     ; IIe/enh?
+        bpl     out             ; No, silently fail
+        .endif
+
         bit     ostype
         bmi     iigs            ; $8x
         bvs     iic             ; $4x
 
-        .ifndef  __APPLE2ENH__
-        bit     machinetype     ; IIe/enh?
-        bmi     :+
-
-        lda     #$FF            ; ][+ Unsupported
-        tax
-        rts
-        .endif
-
+        ; Apple IIe
 :       bit     RDVBLBAR
         bpl     :-              ; Blanking
 :       bit     RDVBLBAR
         bmi     :-              ; Drawing
-        bpl     out
+        rts
 
         ; Apple IIgs TechNote #40, VBL Signal
 iigs:   bit     RDVBLBAR
         bmi     iigs            ; Blanking
 :       bit     RDVBLBAR
         bpl     :-              ; Drawing
-        bmi     out
+        rts
 
         ; Apple IIc TechNote #9, Detecting VBL
 iic:    php
@@ -53,6 +50,4 @@ iic:    php
         bit     DISVBL
 :       sta     IOUDISON        ; IIc Tech Ref Man: The firmware normally leaves IOUDIS on.
         plp
-out:    lda     #$00
-        tax
-        rts
+out:    rts