// #LAYOUT# STD *        #TAKE
// #LAYOUT# X16 *        #IGNORE
// #LAYOUT# *   KERNAL_0 #TAKE
// #LAYOUT# *   *        #IGNORE

//
// Screen code to PETSCII conversion - see:
//
// - https://www.lemon64.com/forum/viewtopic.php?t=66362
// - https://sta.c64.org/cbm64scrtopetext.html
//


screen_code_to_petscii:

	cmp #$20
	bcc s2p_adc_40                     // $00-$1F -> $40-$5F

	cmp #$40
	bcc s2p_end                        // $20-$3F -> $20-$3F

	cmp #$60
	bcc s2p_adc_80                     // $40-$5F -> $C0-$DF

	cmp #$80
	bcc s2p_adc_40                     // $60-$7F -> $A0-$BF

	// Here we have to check for quote mode

	bit QTSW
	bmi screen_code_to_petscii_quote

	// Not quote mode - continue

	cmp #$A0
	bcc s2p_adc_C0                     // $80-$9F -> $40-$5F

	cmp #$C0
	bcc s2p_adc_80                     // $A0-$BF -> $20-$3F

	cmp #$E0
	bcc s2p_end                        // $C0-$DF -> $C0-$DF

	clc
	bcc s2p_adc_C0                     // $E0-$FF -> $A0-$BF

s2p_adc_40:

	adc #$40                           // Carry already clear

s2p_end:

	rts

s2p_adc_80:

	adc #$80                           // Carry already clear
	rts

screen_code_to_petscii_quote:

	cmp #$C0
	bcc s2p_adc_80                     // $80-$BF -> $00-$3F

	clc

	// FALLTROUGH                         $C0-$FF -> $80-$BF

s2p_adc_C0:

	adc #$C0                           // Carry already clear
	rts