From a458fb0b5869eee6c433d5f55a20510201073b40 Mon Sep 17 00:00:00 2001
From: Paul Gardner-Stephen <paul@servalproject.org>
Date: Mon, 22 Apr 2019 01:37:02 +0930
Subject: [PATCH] implement reverse video flag

---
 c64/kernal/chrout.s | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/c64/kernal/chrout.s b/c64/kernal/chrout.s
index 346bd550..7ffa78c7 100644
--- a/c64/kernal/chrout.s
+++ b/c64/kernal/chrout.s
@@ -48,6 +48,19 @@ colour_check_loop:
 	jmp chrout_done
 	* dex
 	bpl colour_check_loop
+
+	cmp #$12
+	bne not_12
+	lda #$80
+	sta reverse_video_flag
+	jmp chrout_done
+not_12:
+	cmp #$92
+	bne not_92
+	lda #$00
+	sta reverse_video_flag
+	jmp chrout_done
+not_92:	
 	
 	;; Check for cursor movement keys
 	cmp #$11
@@ -183,6 +196,7 @@ not_vendor:
 chrout_l1:	
 	;; Write normal character on the screen
 	ldy current_screen_x
+	ora reverse_video_flag
 	sta (current_screen_line_ptr),y
 
 	;; Set colour