From b8dbe0254afc92f1281463f2f13381a9c7c973f9 Mon Sep 17 00:00:00 2001
From: Karri Kaksonen <karri@sipo.fi>
Date: Mon, 4 Apr 2022 15:18:40 +0300
Subject: [PATCH] Add cputc method

---
 libsrc/atari7800/cputc.s | 144 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)
 create mode 100644 libsrc/atari7800/cputc.s

diff --git a/libsrc/atari7800/cputc.s b/libsrc/atari7800/cputc.s
new file mode 100644
index 000000000..5f4346868
--- /dev/null
+++ b/libsrc/atari7800/cputc.s
@@ -0,0 +1,144 @@
+;
+; Mark Keates, Christian Groessler, Piotr Fusik, Karri Kaksonen
+;
+; void cputcxy (unsigned char x, unsigned char y, char c);
+; void cputc (char c);
+;
+
+        .export         _cputc
+	.export		_textcolor
+        .import         _gotoxy, _gotox, _gotoy, tosaddax, tosumula0, pusha0
+	.import		pushax
+	.import		_screen
+        .importzp       ptr1
+	.import		CURS_X, CURS_Y
+
+        .include        "atari7800.inc"
+
+	.data
+;-----------------------------------------------------------------------------
+; Holder of the text colour offset
+; 0 = red, 42 = green, 82 = white
+;
+txtcolor:
+	.byte	0
+
+	.code
+
+;-----------------------------------------------------------------------------
+; Change the text colour
+;
+; Logical colour names are
+; 0 = red
+; 1 = green
+; 2 = white
+;
+; The routine will also return the previous textcolor
+;
+        .proc   _textcolor
+
+	beq	@L2
+	sec
+	sbc	#1
+	beq	@L1
+	lda	#82
+	jmp	@L2
+@L1:	lda	#42
+@L2:	ldy	txtcolor
+	sta	txtcolor
+	tya
+	bne	@L3
+	rts
+@L3:	sec
+	sbc	#42
+	bne	@L4
+	lda	#1
+	rts
+@L4:	lda #2
+	rts
+        .endproc
+
+;-----------------------------------------------------------------------------
+; Put a character on screen
+;
+; The code will handle newlines that wrap to start of screen
+;
+        .proc   _cputc
+
+	cmp     #$0A            ; LF
+        beq     @L3
+        cmp	#$20		; ' '
+        beq     @L1
+
+        jsr     @L5
+@L1:
+        lda	CURS_X
+	cmp	#(charsperline-1)
+        bne     @L2
+	jmp	@L3
+@L2:
+	clc
+	adc	#1
+	jmp	_gotox
+
+@L3:
+	lda	#0
+	jsr	_gotox
+        lda	CURS_Y
+	cmp	#(screenrows-1)
+        bne     @L4
+	lda	#0
+	jmp	_gotoy
+@L4:
+        clc
+	adc	#1
+	jmp	_gotoy
+
+@L5:
+	cmp	#$3F		; '?'
+	bne	@L6
+	lda	#$01
+	jmp	@L10
+@L6:
+	cmp	#$7C		; '|'
+	bne	@L7
+	lda	#$05
+	jmp	@L10
+@L7:
+	cmp	#$41		; >= 'A'
+	bcc	@L8
+	and	#$5F
+	sec
+	sbc	#($41 - 16)
+	jmp	@L10
+@L8:
+	sec
+	sbc	#($2A)
+@L10:
+	sec
+	adc	txtcolor
+	asl
+	pha
+
+	lda	CURS_Y
+	jsr	pusha0
+	lda	#charsperline
+	jsr	tosumula0
+	clc
+	adc	CURS_X
+	bcc	@L11
+	inx
+@L11:	jsr	pushax
+	lda     #<(_screen)
+	ldx     #>(_screen)
+	jsr     tosaddax
+	sta	ptr1
+	stx	ptr1+1
+
+	pla
+	ldy	#0
+	sta	(ptr1),y
+	rts
+
+        .endproc
+