basic: allow multiple args in print

Things are getting super cereal...

apps/basic/glue.asm

@@ -9,15 +9,21 @@
 
 	jp	basStart
 
+; RAM space used in different routines for short term processing.
+.equ	SCRATCHPAD_SIZE	0x20
+.equ	SCRATCHPAD	USER_RAMSTART
+
 .inc "core.asm"
 .inc "lib/util.asm"
 .inc "lib/ari.asm"
 .inc "lib/parse.asm"
 .inc "lib/fmt.asm"
-.equ	EXPR_PARSE	parseLiteral
+.equ	EXPR_PARSE	parseLiteralOrVar
 .inc "lib/expr.asm"
 .inc "basic/tok.asm"
-.equ	BUF_RAMSTART	USER_RAMSTART
+.equ	VAR_RAMSTART	SCRATCHPAD+SCRATCHPAD_SIZE
+.inc "basic/var.asm"
+.equ	BUF_RAMSTART	VAR_RAMEND
 .inc "basic/buf.asm"
 .equ	BAS_RAMSTART	BUF_RAMEND
 .inc "basic/main.asm"

apps/basic/main.asm

@@ -1,28 +1,29 @@
-; *** Constants ***
-.equ	BAS_SCRATCHPAD_SIZE	0x20
 ; *** Variables ***
 ; Value of `SP` when basic was first invoked. This is where SP is going back to
 ; on restarts.
 .equ	BAS_INITSP	BAS_RAMSTART
-; **Pointer** to current line number
-.equ	BAS_PCURLN	@+2
-.equ	BAS_SCRATCHPAD	@+2
-.equ	BAS_RAMEND	@+BAS_SCRATCHPAD_SIZE
+; Pointer to next line to run. If nonzero, it means that the next line is
+; the first of the list. This is used by GOTO to indicate where to jump next.
+; Important note: this is **not** a line number, it's a pointer to a line index
+; in buffer. If it's not zero, its a valid pointer.
+.equ	BAS_PNEXTLN	@+2
+.equ	BAS_RAMEND	@+2
 
 ; *** Code ***
 basStart:
 	ld	(BAS_INITSP), sp
+	call	varInit
 	call	bufInit
 	xor	a
+	ld	(BAS_PNEXTLN), a
+	ld	(BAS_PNEXTLN+1), a
 	ld	hl, .welcome
 	call	printstr
 	call	printcrlf
-	ld	hl, .welcome+2		; points to a zero word
-	ld	(BAS_PCURLN), hl
 	jr	basLoop
 
 .welcome:
-	.db "OK", 0, 0
+	.db "OK", 0
 
 basLoop:
 	ld	hl, .sPrompt
@@ -39,8 +40,8 @@ basLoop:
 	jr	basLoop
 .number:
 	push	ix \ pop de
-	call	toWS
-	call	rdWS
+	call	toSep
+	call	rdSep
 	call	bufAdd
 	jp	nz, basERR
 	jr	basLoop
@@ -52,7 +53,10 @@ basLoop:
 ; on success. Therefore, when calling basCallCmd results in NZ, we're not sure
 ; where the error come from, but well...
 basCallCmd:
-	; First, get cmd length
+	; let's see if it's a variable assignment.
+	call	varTryAssign
+	ret	z	; Done!
+	; Second, get cmd length
 	call	fnWSIdx
 	cp	7
 	jp	nc, unsetZ	; Too long, can't possibly fit anything.
@@ -79,17 +83,13 @@ basCallCmd:
 	ex	de, hl
 	ld	a, b	; cmd's length
 	call	addHL
-	call	rdWS
+	call	rdSep
 	jp	(ix)
 
-
-basPrintLn:
-	call	printstr
-	jp	printcrlf
-
 basERR:
 	ld	hl, .sErr
-	jr	basPrintLn
+	call	printstr
+	jp	printcrlf
 .sErr:
 	.db	"ERR", 0
 
@@ -102,7 +102,8 @@ basERR:
 ; Commands are expected to set Z on success.
 basBYE:
 	ld	hl, .sBye
-	call	basPrintLn
+	call	printstr
+	call	printcrlf
 	; To quit the loop, let's return the stack to its initial value and
 	; then return.
 	xor	a
@@ -117,7 +118,7 @@ basLIST:
 .loop:
 	ld	e, (ix)
 	ld	d, (ix+1)
-	ld	hl, BAS_SCRATCHPAD
+	ld	hl, SCRATCHPAD
 	call	fmtDecimal
 	call	printstr
 	ld	a, ' '
@@ -132,6 +133,8 @@ basLIST:
 
 
 basRUN:
+	call	.maybeGOTO
+	jr	nz, .loop	; IX already set
 	call	bufFirst
 	ret	nz
 .loop:
@@ -141,6 +144,8 @@ basRUN:
 	call	basCallCmd
 	pop	ix		; <-- lvl 1
 	jp	nz, .err
+	call	.maybeGOTO
+	jr	nz, .loop	; IX already set
 	call	bufNext
 	jr	z, .loop
 	cp	a		; ensure Z
@@ -149,23 +154,69 @@ basRUN:
 	; Print line number, then return NZ (which will print ERR)
 	ld	e, (ix)
 	ld	d, (ix+1)
-	ld	hl, BAS_SCRATCHPAD
+	ld	hl, SCRATCHPAD
 	call	fmtDecimal
 	call	printstr
 	ld	a, ' '
 	call	stdioPutC
 	jp	unsetZ
 
-.runline:
+; This returns the opposite Z result as the one we usually see: Z is set if
+; we **don't** goto, unset if we do. If we do, IX is properly set.
+.maybeGOTO:
+	ld	de, (BAS_PNEXTLN)
+	ld	a, d
+	or	e
+	ret	z
+	; we goto
+	push	de \ pop ix
+	; we need to reset our goto marker
+	ld	de, 0
+	ld	(BAS_PNEXTLN), de
+	ret
 
 basPRINT:
+	ld	de, SCRATCHPAD
+	call	rdWord
+	push	hl		; --> lvl 1
+	ex	de, hl
 	call	parseExpr
 	ret	nz
 	push	ix \ pop de
-	ld	hl, BAS_SCRATCHPAD
+	ld	hl, SCRATCHPAD
 	call	fmtDecimal
+	call	printstr
+	pop	hl		; <-- lvl 1
+	; Do we have another arg?
+	call	rdSep
+	jr	z, .another
+	; no, we can stop here
 	cp	a		; ensure Z
-	jp	basPrintLn
+	jp	printcrlf
+.another:
+	; Before we jump to basPRINT, let's print a space
+	ld	a, ' '
+	call	stdioPutC
+	jr	basPRINT
+
+basGOTO:
+	ld	de, SCRATCHPAD
+	call	rdWord
+	ex	de, hl
+	call	parseExpr
+	ret	nz
+	push	ix \ pop de
+	call	bufFind
+	jr	nz, .notFound
+	push	ix \ pop de
+	; Z already set
+	jr	.end
+.notFound:
+	ld	de, 0
+	; Z already unset
+.end:
+	ld	(BAS_PNEXTLN), de
+	ret
 
 ; direct only
 basCmds1:
@@ -179,4 +230,6 @@ basCmds1:
 basCmds2:
 	.dw	basPRINT
 	.db	"print", 0
+	.dw	basGOTO
+	.db	"goto", 0, 0
 	.db	0xff, 0xff, 0xff	; end of table

apps/basic/tok.asm

@@ -1,3 +1,12 @@
+; Sets Z is A is ' ' or '\t' (whitespace), or ',' (arg sep)
+isSep:
+	cp	' '
+	ret	z
+	cp	0x09
+	ret	z
+	cp	','
+	ret
+
 ; Expect at least one whitespace (0x20, 0x09) at (HL), and then advance HL
 ; until a non-whitespace character is met.
 ; HL is advanced to the first non-whitespace char.
@@ -5,7 +14,7 @@
 ; Failure is either not having a first whitespace or reaching the end of the
 ; string.
 ; Sets Z if we found a non-whitespace char, unset if we found the end of string.
-rdWS:
+rdSep:
 	ld	a, (hl)
 	call	isSep
 	ret	nz	; failure
@@ -47,10 +56,32 @@ fnWSIdx:
 	pop	hl
 	ret
 
-; Advance HL to the next whitespace or to the end of string.
-toWS:
+; Advance HL to the next separator or to the end of string.
+toSep:
 	ld	a, (hl)
 	call	isSep
 	ret	z
 	inc	hl
-	jr	toWS
+	jr	toSep
+
+; 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.
+rdWord:
+	push	af
+	push	de
+.loop:
+	ld	a, (hl)
+	call	isSep
+	jr	z, .stop
+	or	a
+	jr	z, .stop
+	ld	(de), a
+	inc	hl
+	inc	de
+	jr	.loop
+.stop:
+	xor	a
+	ld	(de), a
+	pop	de
+	pop	af
+	ret

apps/basic/var.asm

@@ -0,0 +1,101 @@
+; *** Variables ***
+; A list of words for each member of the A-Z range.
+.equ	VAR_TBL		VAR_RAMSTART
+.equ	VAR_RAMEND	@+52
+
+; *** Code ***
+
+varInit:
+	ld	b, VAR_RAMEND-VAR_RAMSTART
+	ld	hl, VAR_RAMSTART
+	xor	a
+.loop:
+	ld	(hl), a
+	inc	hl
+	djnz	.loop
+	ret
+
+; Check if A is a valid variable letter (a-z or A-Z). If it is, set A to a
+; valid VAR_TBL index and set Z. Otherwise, unset Z (and A is destroyed)
+varChk:
+	call	upcase
+	sub	'A'
+	ret	c	; Z unset
+	cp	27	; 'Z' + 1
+	jr	c, .isVar
+	; A > 'Z'
+	dec	a	; unset Z
+	ret
+.isVar:
+	cp	a	; set Z
+	ret
+
+; Try to interpret line at (HL) and see if it's a variable assignment. If it
+; is, proceed with the assignment and set Z. Otherwise, NZ.
+varTryAssign:
+	inc	hl
+	ld	a, (hl)
+	dec	hl
+	cp	'='
+	ret	nz
+	ld	a, (hl)
+	call	varChk
+	ret	nz
+	; We have a variable! Its table index is currently in A.
+	push	ix	; --> lvl 1
+	push	hl	; --> lvl 2
+	push	de	; --> lvl 3
+	push	af	; --> lvl 4. save for later
+	; Let's put that expression to read in scratchpad
+	inc	hl \ inc hl
+	ld	de, SCRATCHPAD
+	call	rdWord
+	ex	de, hl
+	; Now, evaluate that expression now in (HL)
+	call	parseExpr	; --> number in IX
+	jr	nz, .exprErr
+	pop	af	; <-- lvl 4
+	add	a, a	; * 2 because each element is a word
+	ld	hl, VAR_TBL
+	call	addHL
+	; HL placed, write number
+	push	ix \ pop de
+	ld	(hl), e
+	inc	hl
+	ld	(hl), d
+	xor	a	; ensure Z
+.end:
+	pop	de	; <-- lvl 3
+	pop	hl	; <-- lvl 2
+	pop	ix	; <-- lvl 1
+	ret
+.exprErr:
+	pop	af	; <-- lvl 4
+	jr	.end
+
+; Check if value at (HL) is a variable. If yes, returns its associated value.
+; Otherwise, jump to parseLiteral.
+parseLiteralOrVar:
+	inc	hl
+	ld	a, (hl)
+	dec	hl
+	or	a
+	; if more than one in length, it can't be a variable
+	jp	nz, parseLiteral
+	ld	a, (hl)
+	call	varChk
+	jp	nz, parseLiteral
+	; It's a variable, resolve!
+	add	a, a	; * 2 because each element is a word
+	push	hl	; --> lvl 1
+	ld	hl, VAR_TBL
+	call	addHL
+	push	de	; --> lvl 2
+	ld	e, (hl)
+	inc	hl
+	ld	d, (hl)
+	push	de \ pop ix
+	pop	de	; <-- lvl 2
+	pop	hl	; <-- lvl 1
+	cp	a	; ensure Z
+	ret

apps/lib/parse.asm

@@ -132,7 +132,7 @@ parseDecimal:
 	pop	hl
 	ret	z
 	; A is not 0? Ok, but if it's a space, we're happy too.
-	jp	isSep
+	jp	isWS
 .error:
 	pop	hl
 	jp	unsetZ

apps/lib/util.asm

@@ -1,5 +1,5 @@
-; Sets Z is A is ' ' or '\t'
-isSep:
+; Sets Z is A is ' ' or '\t' (whitespace)
+isWS:
 	cp	' '
 	ret	z
 	cp	0x09

apps/zasm/tok.asm

@@ -31,7 +31,7 @@ isLineEnd:
 
 ; Sets Z is A is ' ', ',', ';', CR, LF, or null.
 isSepOrLineEnd:
-	call	isSep
+	call	isWS
 	ret	z
 	jr	isLineEndOrComment
 
@@ -68,7 +68,7 @@ isLabel:
 ; read char in A
 _eatWhitespace:
 	call	ioGetB
-	call	isSep
+	call	isWS
 	ret	nz
 	jr	_eatWhitespace