From 8d0b0e6ffcad7d6d63ccfc212e230d4cab484fa1 Mon Sep 17 00:00:00 2001
From: Karri Kaksonen <karri@sipo.fi>
Date: Fri, 25 Mar 2022 14:44:54 +0200
Subject: [PATCH] Separate machine detection from crt0 and put it in get_tv

---
 libsrc/atari7800/crt0.s   | 27 ---------------
 libsrc/atari7800/get_tv.s | 69 ++++++++++++++++++++++++++++++---------
 2 files changed, 53 insertions(+), 43 deletions(-)

diff --git a/libsrc/atari7800/crt0.s b/libsrc/atari7800/crt0.s
index bd8a57525..d7cf307ee 100644
--- a/libsrc/atari7800/crt0.s
+++ b/libsrc/atari7800/crt0.s
@@ -1,5 +1,4 @@
         .export		_zonecounter
-        .export		_paldetected
         .export		 __STARTUP__ : absolute = 1
         .export		 _exit
         .import		 __ROM_START__
@@ -39,29 +38,6 @@ start:
         jsr     zerobss
         jsr     initlib
 
-	; Examine machine type as we need the info early
-vboff:	lda     MSTAT
-	bmi     vboff
-vbon:   lda     MSTAT
-        bpl     vbon
-vboff2: lda     MSTAT
-        bmi     vboff2
-        lda     #$00
-        sta     _paldetected
-        jmp     mtsta
-count:  sta     WSYNC
-        sta     WSYNC
-        dec     _paldetected
-mtsta:  lda     MSTAT
-        bpl     count
-        lda     _paldetected
-        cmp     #$78
-        bcc     mtntsc
-        lda     #$01
-        jmp     mtpal
-mtntsc: lda     #$00
-mtpal:  sta     _paldetected
-
         ; Call main program (pass empty command line)
         jsr     push0           ; argc
         jsr     push0           ; argv
@@ -82,9 +58,6 @@ IRQHandler:
         .segment "DATA"
 _zonecounter:
         .byte   0
-_paldetected:
-	.byte	0		; 0 = NTSC, 1 = PAL
-
 
         .segment "ENCRYPTION"
         .res    126, $ff        ; Reserved for encryption
diff --git a/libsrc/atari7800/get_tv.s b/libsrc/atari7800/get_tv.s
index 307a5c58d..5438b2b95 100644
--- a/libsrc/atari7800/get_tv.s
+++ b/libsrc/atari7800/get_tv.s
@@ -1,26 +1,63 @@
 ;
-; Stefan Haubenthal, 2007-01-21
+; Karri Kaksonen, 2022-03-25
 ;
-; unsigned char get_tv (void);
-; /* Return the video mode the machine is using */
+; unsigned char get_tv (void)
 ;
+	.include	"atari7800.inc"
+	.export		_get_tv
 
-        .include        "atari7800.inc"
-        .include        "get_tv.inc"
-        .importzp       tmp1, tmp2
-	.import		_paldetected
+.segment	"DATA"
 
-;--------------------------------------------------------------------------
-; _get_tv
+_paldetected:
+	.byte	$FF
 
-.proc   _get_tv
+; ---------------------------------------------------------------
+; unsigned char get_tv (void)
+; ---------------------------------------------------------------
 
-        lda	_paldetected
-	beq	ntsc
-	lda	#TV::PAL
-	rts
-ntsc:
-	lda	#TV::NTSC
+.segment	"CODE"
+
+.proc	_get_tv: near
+
+.segment	"CODE"
+
+	ldx     #$00
+	lda     #$FF
+	cmp     _paldetected
+	bne     L8
+L1:	lda     $0028
+	and     #$80
+	bne     L1
+L2:	lda     $0028
+	and     #$80
+	beq     L2
+L3:	lda     $0028
+	and     #$80
+	bne     L3
+	lda     #$00
+	sta     M0001
+	jmp     L5
+L4:	sta     $0024
+	sta     $0024
+	dec     M0001
+L5:	lda     $0028
+	and     #$80
+	beq     L4
+	lda     M0001
+	cmp     #$78
+	bcc     L6
+	lda     #$00
+	jmp     L7
+L6:	lda     #$01
+L7:	sta     _paldetected
+	ldx     #$00
+L8:	lda     _paldetected
 	rts
 
+.segment	"BSS"
+
+M0001:
+	.res	1,$00
+
 .endproc
+