From dd6ce2fdddbc9f988f1bcc52cbedca6c0a24f99d Mon Sep 17 00:00:00 2001
From: cuz <cuz@b7a2c559-68d2-44c3-8de9-860c34a00d81>
Date: Fri, 8 Oct 2004 20:23:15 +0000
Subject: [PATCH] New get_tv function from Stefan Haubenthal

git-svn-id: svn://svn.cc65.org/cc65/trunk@3230 b7a2c559-68d2-44c3-8de9-860c34a00d81
---
 libsrc/vic20/get_tv.s | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 libsrc/vic20/get_tv.s

diff --git a/libsrc/vic20/get_tv.s b/libsrc/vic20/get_tv.s
new file mode 100644
index 000000000..13c5c428a
--- /dev/null
+++ b/libsrc/vic20/get_tv.s
@@ -0,0 +1,33 @@
+;
+; Stefan Haubenthal, 2004-10-07
+; Based on code from Pu-239
+;
+; unsigned char __fastcall__ get_tv (void);
+; /* Return the video mode the machine is using */
+;
+
+	.export		_get_tv
+
+	.include	"vic20.inc"
+
+
+;--------------------------------------------------------------------------
+; _get_tv
+
+.proc	_get_tv
+
+NTSC_LINES = 261
+	; detect the system
+	lda	#0
+	tax
+@L0:	ldy	VIC_HLINE
+	cpy	#1
+	bne	@L0		; wait for line 1
+@L1:	ldy	VIC_HLINE
+	beq	@L2		; line 0 reached -> NTSC
+	cpy	#NTSC_LINES/2+2
+	bne	@L1
+	lda	#1
+@L2:	rts			; system detected: 0 for NTSC, 1 for PAL
+
+.endproc
-- 
2.39.5