From 6f9d28b325334ea660a46aef3e754a2d14cf69e2 Mon Sep 17 00:00:00 2001
From: Virgil Dupras <hsoft@hardcoded.net>
Date: Sat, 7 Mar 2020 13:15:19 -0500
Subject: [PATCH] forth: add word "bye"

And make interpret action looping until BYE.
---
 apps/forth/dict.asm | 12 +++++++++++-
 apps/forth/main.asm | 19 ++++++++++++++++---
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/apps/forth/dict.asm b/apps/forth/dict.asm
index 44afe6e..2b128d6 100644
--- a/apps/forth/dict.asm
+++ b/apps/forth/dict.asm
@@ -45,10 +45,19 @@ exit:
 	push	hl \ pop iy
 	jp	compiledWord
 
+BYE:
+	.db "BYE"
+	.fill 5
+	.dw EXIT
+	.dw nativeWord
+	ld	hl, FLAGS
+	set	FLAG_ENDPGM, (hl)
+	jp	exit
+
 ; ( c -- )
 EMIT:
 	.db "EMIT", 0, 0, 0, 0
-	.dw EXIT
+	.dw BYE
 	.dw nativeWord
 	pop	hl
 	ld	a, l
@@ -87,6 +96,7 @@ INTERPRET:
 	.db "INTERPRE"
 	.dw KEY
 	.dw nativeWord
+interpret:
 	call	pad
 	push	hl \ pop iy
 	call	stdioReadLine
diff --git a/apps/forth/main.asm b/apps/forth/main.asm
index b1ad497..98783e4 100644
--- a/apps/forth/main.asm
+++ b/apps/forth/main.asm
@@ -5,32 +5,45 @@
 .equ	PADDING		0x20
 ; Offset of the code link relative to the beginning of the word
 .equ	CODELINK_OFFSET	10
+; When set, the interpret should quit
+.equ	FLAG_ENDPGM	1
 
 ; *** Variables ***
 .equ	INITIAL_SP	FORTH_RAMSTART
 .equ	CURRENT		@+2
 .equ	HERE		@+2
 .equ	INPUTPOS	@+2
-.equ	FORTH_RAMEND	@+2
+.equ	FLAGS		@+2
+.equ	FORTH_RAMEND	@+1
 
 ; *** Code ***
 MAIN:
 	.dw compiledWord
 	.dw INTERPRET+CODELINK_OFFSET
-	.dw ENDPGM
+	.dw CHKEND
 
-ENDPGM:
+; If FLAG_ENDPGM is set, stop the program, else, tweak the RS so that we loop.
+CHKEND:
 	.dw nativeWord
+	ld	hl, FLAGS
+	bit	FLAG_ENDPGM, (hl)
+	jr	nz, .endpgm
+	; not quitting, loop
+	jr	forthLoop
+.endpgm:
 	ld	sp, (INITIAL_SP)
 	xor	a
 	ret
 
 forthMain:
+	xor	a
+	ld	(FLAGS), a
 	ld	(INITIAL_SP), sp
 	ld	hl, DOT		; last entry in hardcoded dict
 	ld	(CURRENT), hl
 	ld	hl, FORTH_RAMEND
 	ld	(HERE), hl
+forthLoop:
 	ld	ix, RS_ADDR
 	ld	iy, MAIN
 	jp	executeCodeLink