From 51c977f2ed9d7e110ca6fd63da1d557f0660e9da Mon Sep 17 00:00:00 2001
From: Virgil Dupras <hsoft@hardcoded.net>
Date: Thu, 12 Dec 2019 10:51:13 -0500
Subject: [PATCH] basic: allow multiple commands on the same line

---
 apps/basic/README.md | 13 +++++++++++--
 apps/basic/fs.asm    |  2 +-
 apps/basic/main.asm  | 32 +++++++++++++++++++++++++++-----
 apps/basic/tok.asm   | 41 ++++++++++++++++++++++++++++++-----------
 4 files changed, 69 insertions(+), 19 deletions(-)

diff --git a/apps/basic/README.md b/apps/basic/README.md
index 8a31e47..8af3b08 100644
--- a/apps/basic/README.md
+++ b/apps/basic/README.md
@@ -88,13 +88,22 @@ etc.) always to so in variable `A`.
 Another is that whenever a number is expected, expressions, including the ones
 with variables in it, work fine.
 
+### One-liners
+
+The `:` character, when not inside a `""` literal, allows you to cram more than
+one instruction on the same line.
+
+Things are special with `if`. All commands following a `if` are bound to that
+`if`'s condition. `if 0 foo:bar` doesn't execute `bar`.
+
+Another special thing is `goto`. A `goto` followed by `:` will have the commands
+following the `:` before the goto occurs.
+
 ### Commands
 
 There are two types of commands: normal and direct-only. The latter can only
 be invoked in direct mode, not through a code listing.
 
-`bye`: Direct-only. Quits BASIC
-
 `list`: Direct-only. Prints all lines in the code listing, prefixing them
 with their associated line number.
 
diff --git a/apps/basic/fs.asm b/apps/basic/fs.asm
index 23a8f0c..7cce471 100644
--- a/apps/basic/fs.asm
+++ b/apps/basic/fs.asm
@@ -46,7 +46,7 @@ basLDBAS:
 	call	parseDecimal
 	jr	nz, .notANumber
 	push	ix \ pop de
-	call	toSep
+	call	toSepOrEnd
 	call	rdSep
 	call	bufAdd
 	pop	hl		; <-- lvl 1
diff --git a/apps/basic/main.asm b/apps/basic/main.asm
index 56db9ab..f4559f7 100644
--- a/apps/basic/main.asm
+++ b/apps/basic/main.asm
@@ -41,14 +41,14 @@ basLoop:
 	call	parseDecimal
 	jr	z, .number
 	ld	de, basCmds1
-	call	basCallCmd
+	call	basCallCmds
 	jr	z, basLoop
 	; Error
 	call	basERR
 	jr	basLoop
 .number:
 	push	ix \ pop de
-	call	toSep
+	call	toSepOrEnd
 	call	rdSep
 	call	bufAdd
 	jp	nz, basERR
@@ -110,6 +110,27 @@ basCallCmd:
 	call	rdSep
 	jp	(ix)
 
+; Call a series of ':'-separated commands in (HL) using cmd table in (DE).
+; Stop processing as soon as one command unsets Z.
+basCallCmds:
+	; Commands are not guaranteed at all to preserve HL and DE, so we
+	; preserve them ourselves here.
+	push	hl	; --> lvl 1
+	push	de	; --> lvl 2
+	call	basCallCmd
+	pop	de	; <-- lvl 2
+	pop	hl	; <-- lvl 1
+	ret	nz
+	call	toEnd
+	ret	z	; no more cmds
+	; we met a ':', we have more cmds
+	inc	hl
+	call	basCallCmds
+	; move the the end of the string so that we don't run cmds following a
+	; ':' twice.
+	call	strskip
+	ret
+
 basERR:
 	ld	hl, .sErr
 	call	printstr
@@ -154,7 +175,7 @@ basRUN:
 	call	bufStr
 	ld	de, basCmds2
 	push	ix		; --> lvl 1
-	call	basCallCmd
+	call	basCallCmds
 	pop	ix		; <-- lvl 1
 	jp	nz, .err
 	call	.maybeGOTO
@@ -258,10 +279,11 @@ basIF:
 	ret	z
 	; expr is true, execute next
 	; (HL) back to beginning of args, skip to next arg
-	call	toSep
+	call	toSepOrEnd
 	call	rdSep
+	ret	nz
 	ld	de, basCmds2
-	jp	basCallCmd
+	jp	basCallCmds
 
 basINPUT:
 	; If our first arg is a string literal, spit it
diff --git a/apps/basic/tok.asm b/apps/basic/tok.asm
index 1e6c630..e6adf41 100644
--- a/apps/basic/tok.asm
+++ b/apps/basic/tok.asm
@@ -1,10 +1,16 @@
-; Sets Z is A is ' ' or '\t' (whitespace), or ',' (arg sep)
+; Whether A is a separator or end-of-string (null or ':')
+isSepOrEnd:
+	or	a
+	ret	z
+	cp	':'
+	ret	z
+	; continue to isSep
+
+; Sets Z is A is ' ' or '\t' (whitespace)
 isSep:
 	cp	' '
 	ret	z
 	cp	0x09
-	ret	z
-	cp	','
 	ret
 
 ; Expect at least one whitespace (0x20, 0x09) at (HL), and then advance HL
@@ -23,8 +29,8 @@ rdSep:
 	ld	a, (hl)
 	call	isSep
 	jr	z, .loop
-	or	a	; cp 0
-	jp	z, .fail
+	call	isSepOrEnd
+	jp	z, .fail	; unexpected EOL. fail
 	cp	a	; ensure Z
 	ret
 .fail:
@@ -33,12 +39,27 @@ rdSep:
 	ret
 
 ; Advance HL to the next separator or to the end of string.
-toSep:
+toSepOrEnd:
 	ld	a, (hl)
-	call	isSep
+	call	isSepOrEnd
 	ret	z
 	inc	hl
-	jr	toSep
+	jr	toSepOrEnd
+
+; Advance HL to the end of the line, that is, either a null terminating char
+; or the ':'.
+; Sets Z if we met a null char, unset if we met a ':'
+toEnd:
+	ld	a, (hl)
+	or	a
+	ret	z
+	cp	':'
+	jr	z, .havesep
+	inc	hl
+	jr	toEnd
+.havesep:
+	inc	a	; unset Z
+	ret
 
 ; Read (HL) until the next separator and copy it in (DE)
 ; DE is preserved, but HL is advanced to the end of the read word.
@@ -47,9 +68,7 @@ rdWord:
 	push	de
 .loop:
 	ld	a, (hl)
-	call	isSep
-	jr	z, .stop
-	or	a
+	call	isSepOrEnd
 	jr	z, .stop
 	ld	(de), a
 	inc	hl