visual improvements

src/basic/basic_commands/helper_eggshell_m65.s

@@ -13,7 +13,119 @@ helper_eggshell:
 
 } else {
 
-	; XXX implement till Easter
+	; Make sure this is direct mode
+
+	ldx CURLIN+1
+	inx
+	bne helper_eggshell_end
+
+	; Make sure this is native mode
+
+	jsr M65_MODEGET
+	bcs helper_eggshell_end
+
+	; Make sure screen mode is 80x50 characters and it is the output device
+
+	jsr JSCREEN
+	cpy #50
+	bne helper_eggshell_end
+	cpx #80
+	bne helper_eggshell_end
+
+	lda DFLTO
+	cmp #$03
+	bne helper_eggshell_end
+
+	; Check key values
+
+	ldx #$03
+@1:
+	lda INDEX, x
+	cmp helper_eggshell_key, x
+	bne helper_eggshell_end
+	dex
+	bpl @1
+
+	; FALLTROUGH
+
+helper_eggshell_prepare:
+
+	; Enforce lowercase mode
+
+	lda MODE
+	pha
+	lda #$FF
+	sta MODE
+
+	lda VIC_CHARPTR+1
+	pha
+	ora #%00001000
+	sta VIC_CHARPTR+1
+
+	; FALLTROUGH
+
+helper_eggshell_effect:
+
+	ldy #$00
+@1:
+	lda helper_eggshell_content, y
+	eor #$65
+	beq helper_eggshell_wait
+	jsr JCHROUT
+	iny
+	bra @1
+
+	; FALLTROUGH
+
+helper_eggshell_wait:
+
+	; Wait for a key
+
+	lda #$00
+	sta NDX
+@1:
+	ldx NDX
+	beq @1
+	sta NDX
+
+	; FALLTROUGH
+
+helper_eggshell_restore:
+
+	; Clear screen, restore mode
+
+	lda #147
+	jsr JCHROUT
+
+	pla
+	sta VIC_CHARPTR+1
+
+	pla
+	sta MODE
+
+	; FALLTROUGH
+
+helper_eggshell_end:
 
 	rts
+
+helper_eggshell_key:
+
+	!byte <6502, >6502, 65, 0
+
+helper_eggshell_content:
+
+	!byte $93 XOR $65
+
+	!byte $0D XOR $65, $0D XOR $65, $0D XOR $65, $0D XOR $65
+	!byte $12 XOR $65, $20 XOR $65
+	!byte $D4 XOR $65, $48 XOR $65, $45 XOR $65, $20 XOR $65, $CF XOR $65, $50 XOR $65, $45 XOR $65, $4E XOR $65
+	!byte $20 XOR $65, $D2 XOR $65, $CF XOR $65, $CD XOR $65, $53 XOR $65, $20 XOR $65, $50 XOR $65, $52 XOR $65
+	!byte $4F XOR $65, $4A XOR $65, $45 XOR $65, $43 XOR $65, $54 XOR $65, $20 XOR $65, $4E XOR $65, $45 XOR $65
+	!byte $45 XOR $65, $44 XOR $65, $53 XOR $65, $20 XOR $65, $D9 XOR $65, $CF XOR $65, $D5 XOR $65, $D2 XOR $65
+	!byte $20 XOR $65, $43 XOR $65, $4F XOR $65, $4E XOR $65, $54 XOR $65, $52 XOR $65, $49 XOR $65, $42 XOR $65
+	!byte $55 XOR $65, $54 XOR $65, $49 XOR $65, $4F XOR $65, $4E XOR $65, $21 XOR $65
+	!byte $20 XOR $65 
+
+	!byte $00 XOR $65
 }