CODE.md

@@ -51,25 +51,6 @@ Therefore, shadow registers should only be used in code that doesn't call
 routines or that call a routine that explicitly states that it preserves
 shadow registers.
 
-Another important note is that routines returning success with Z generally don't
-preserve AF: too complicated. But otherwise, AF is often preserved. For example,
-register fiddling routines in core try to preserve AF.
-
-## Z for success
-
-The vast majority of routines use the Z flag to indicate success. When Z is set,
-it indicates success. When Z is unset, it indicates error. This follows the
-tradition of a zero indicating success and a nonzero indicating error.
-
-Important note: only Z indicate success. Many routines return a meaningful
-nonzero value in A and still set Z to indicate success.
-
-In error conditions, however, most of the time A is set to an error code.
-
-In many routines, this is specified verbosely, but it's repeated so often that
-I started writing it in short form, "Z for success", which means what is
-described here.
-
 ## Stack management
 
 Keeping the stack "balanced" is a big challenge when writing assembler code.
@@ -106,12 +87,4 @@ comments. Example:
     pop     af  ; <-- lvl 1
 
 I think that this should do the trick, so I'll do this consistently from now on.
-
-## String length
-
-Pretty much every routine expecting a string have no provision for a string
-that doesn't have null termination within 0xff bytes. Treat strings of such
-lengths with extra precaution and distrust proper handling of existing routines
-for those strings.
-
 [zasm]: ../apps/zasm/README.md

apps/basic/README.md

@@ -14,17 +14,3 @@ writing from scratch, so here I am, writing from scratch again...
 The biggest challenge here is to extract code from zasm, adapt it to fit BASIC,
 not break anything, and have the wisdom to see when copy/pasting is a better
 idea.
-
-## Design goal
-
-The reason for including a BASIC dialect in Collapse OS is to supply some form
-of system administration swiss knife. zasm, ed and the shell can do
-theoretically anything, but some tasks (which are difficult to predict) can
-possibly be overly tedious. One can think, for example, about hardware
-debugging. Poking and peeking around when not sure what we're looking for can
-be a lot more effective with the help of variables, conditions and for-loops in
-an interpreter.
-
-Because the goal is not to provide a foundation for complex programs, I'm
-planning on intentionally crippling this BASIC dialect for the sake of
-simplicity. 

apps/basic/buf.asm

@@ -1,117 +0,0 @@
-; *** Consts ***
-; maximum number of lines (line number maximum, however, is always 0xffff)
-.equ	BUF_MAXLINES	0x100
-; Size of the string pool
-.equ	BUF_POOLSIZE	0x1000
-
-; *** Variables ***
-; A pointer to the first free line
-.equ	BUF_LFREE	BUF_RAMSTART
-; A pointer to the first free byte in the pool
-.equ	BUF_PFREE	@+2
-; The line index. Each record consists of 4 bytes: 2 for line number,
-; 2 for pointer to string in pool. Kept in order of line numbers.
-.equ	BUF_LINES	@+2
-; The line pool. A list of null terminated strings. BUF_LINES records point
-; to those strings.
-.equ	BUF_POOL	@+BUF_MAXLINES*4
-.equ	BUF_RAMEND	@+BUF_POOLSIZE
-
-bufInit:
-	ld	hl, BUF_LINES
-	ld	(BUF_LFREE), hl
-	ld	hl, BUF_POOL
-	ld	(BUF_PFREE), hl
-	ret
-
-; Add line at (HL) with line number DE to the buffer. The string at (HL) should
-; not contain the line number prefix or the whitespace between the line number
-; and the comment.
-; Note that an empty string is *not* an error. It will be saved as a line.
-; Z for success.
-; Error conditions are:
-; * not enough space in the pool
-; * not enough space in the line index
-bufAdd:
-	exx			; preserve HL and DE
-	; First step: do we have index space?
-	ld	hl, (BUF_LFREE)
-	ld	de, BUF_POOL
-	or	a		; reset carry
-	sbc	hl, de
-	exx			; restore
-	; no carry? HL >= BUF_POOL, error. Z already unset
-	ret	nc
-	; Second step: see if we're within the pool's bounds
-	call	strlen
-	inc	a		; strlen doesn't include line termination
-	exx			; preserve HL and DE
-	ld	hl, (BUF_PFREE)
-	call	addHL
-	ld	de, BUF_RAMEND
-	sbc	hl, de
-	exx			; restore
-	; no carry? HL >= BUF_RAMEND, error. Z already unset
-	ret	nc
-	; We have enough space.
-	; Third step: set line index data
-	push	de	; --> lvl 1
-	push	hl	; --> lvl 2
-	ld	hl, (BUF_LFREE)
-	ld	(hl), e
-	inc	hl
-	ld	(hl), d
-	inc	hl
-	ld	de, (BUF_PFREE)
-	ld	(hl), e
-	inc	hl
-	ld	(hl), d
-	inc	hl
-	ld	(BUF_LFREE), hl
-	pop	hl \ push hl	; <-- lvl 2, restore and preserve
-
-	; Fourth step: copy string to pool
-	ld	de, (BUF_PFREE)
-	call	strcpyM
-	ld	(BUF_PFREE), de
-	pop	hl	; <-- lvl 2
-	pop	de	; <-- lvl 1
-	ret
-
-; Set IX to point to the beginning of the pool.
-; Z set if (IX) is a valid line, unset if the pool is empty.
-bufFirst:
-	ld	ix, BUF_LINES
-	jp	bufEOF
-
-; Given a valid line record in IX, move IX to the next line.
-; This routine doesn't check that IX is valid. Ensure IX validity before
-; calling.
-bufNext:
-	inc	ix \ inc ix \ inc ix \ inc ix
-	jp	bufEOF
-
-; Returns whether line index at IX is past the end of file, that is,
-; whether IX == (BUF_LFREE)
-; Z is set when not EOF, unset when EOF.
-bufEOF:
-	push	hl
-	push	de
-	push	ix \ pop hl
-	ld	de, (BUF_LFREE)
-	sbc	hl, de
-	jr	z, .empty
-	cp	a		; ensure Z
-.end:
-	pop	de
-	pop	hl
-	ret
-.empty:
-	call	unsetZ
-	jr	.end
-
-; Given a line index in (IX), set HL to its associated string pointer.
-bufStr:
-	ld	l, (ix+2)
-	ld	h, (ix+3)
-	ret

apps/basic/glue.asm

@@ -17,8 +17,6 @@
 .equ	EXPR_PARSE	parseLiteral
 .inc "lib/expr.asm"
 .inc "basic/tok.asm"
-.equ	BUF_RAMSTART	USER_RAMSTART
-.inc "basic/buf.asm"
-.equ	BAS_RAMSTART	BUF_RAMEND
+.equ	BAS_RAMSTART	USER_RAMSTART
 .inc "basic/main.asm"
 USER_RAMSTART:

apps/basic/main.asm

@@ -12,7 +12,6 @@
 ; *** Code ***
 basStart:
 	ld	(BAS_INITSP), sp
-	call	bufInit
 	xor	a
 	ld	hl, .welcome
 	call	printstr
@@ -33,13 +32,12 @@ basPrompt:
 	call	basDirect
 	jr	basPrompt
 .number:
-	push	ix \ pop de
-	call	toWS
-	call	rdWS
-	call	bufAdd
-	jp	nz, basERR
-	call	printcrlf
+	; do nothing for now, we only support direct mode.
+	ld	hl, .sNumber
+	call	basPrintLn
 	jr	basPrompt
+.sNumber:
+	.db "A number!", 0
 .sPrompt:
 	.db "> ", 0
 
@@ -106,26 +104,6 @@ basBYE:
 .sBye:
 	.db	"Goodbye!", 0
 
-basLIST:
-	call	printcrlf
-	call	bufFirst
-	ret	nz
-.loop:
-	ld	e, (ix)
-	ld	d, (ix+1)
-	ld	hl, BAS_SCRATCHPAD
-	call	fmtDecimal
-	call	printstr
-	ld	a, ' '
-	call	stdioPutC
-	call	bufStr
-	call	printstr
-	call	printcrlf
-	call	bufNext
-	jr	z, .loop
-	ret
-
-
 basPRINT:
 	call	parseExpr
 	jp	nz, basERR
@@ -138,8 +116,6 @@ basPRINT:
 basCmds1:
 	.dw	basBYE
 	.db	"bye", 0, 0, 0
-	.dw	basLIST
-	.db	"list", 0, 0
 ; statements
 basCmds2:
 	.dw	basPRINT

apps/basic/tok.asm

@@ -46,11 +46,3 @@ fnWSIdx:
 	pop	bc
 	pop	hl
 	ret
-
-; Advance HL to the next whitespace or to the end of string.
-toWS:
-	ld	a, (hl)
-	call	isSep
-	ret	z
-	inc	hl
-	jr	toWS