apps/ed: refactoring

apps/ed/cmd.asm

@@ -0,0 +1,135 @@
+; cmd - parse and interpret command
+;
+; *** Consts ***
+
+; address type
+
+.equ	ABSOLUTE	0
+; handles +, - and ".". For +, easy. For -, addr is negative. For ., it's 0.
+.equ	RELATIVE	1
+.equ	BOF		2
+.equ	EOF		3
+
+; *** Variables ***
+
+; An address is a one byte type and a two bytes line number (0-indexed)
+.equ	CMD_ADDR1	CMD_RAMSTART
+.equ	CMD_ADDR2	CMD_ADDR1+3
+.equ	CMD_TYPE	CMD_ADDR2+3
+.equ	CMD_RAMEND	CMD_TYPE+1
+
+; *** Code ***
+
+; Parse command line that HL points to and set unit's variables
+; Sets Z on success, unset on error.
+cmdParse:
+	ld	a, (hl)
+	cp	'q'
+	jr	z, .quit
+	ld	(CMD_TYPE), a
+	ld	ix, CMD_ADDR1
+	jp	.readAddr
+.quit:
+	; Z already set
+	ld	(CMD_TYPE), a
+	ret
+
+; Parse the string at (HL) and sets its corresponding address in IX, properly
+; considering implicit values (current address when nothing is specified).
+; advances HL to the char next to the last parsed char.
+; It handles "+" and "-" addresses such as "+3", "-2", "+", "-".
+; Sets Z on success, unset on error. Line out of bounds isn't an error. Only
+; overflows.
+.readAddr:
+	ld	a, (hl)
+	cp	'+'
+	jr	z, .plusOrMinus
+	cp	'-'
+	jr	z, .plusOrMinus
+	call	parseDecimalDigit
+	jr	c, .notHandled
+	; straight number
+	ld	a, ABSOLUTE
+	ld	(ix), a
+	call	.parseDecimalM
+	ret	nz
+	dec	de	; from 1-based to 0-base
+	jr	.end
+.notHandled:
+	; something else. Something we don't handle. Our addr is therefore "."
+	ld	a, RELATIVE
+	ld	(ix), a
+	xor	a		; sets Z
+	ld	(ix+1), a
+	ld	(ix+2), a
+	ret
+.plusOrMinus:
+	push	af		; preserve that + or -
+	ld	a, RELATIVE
+	ld	(ix), a
+	inc	hl		; advance cmd cursor
+	ld	a, (hl)
+	ld	de, 1		; if .pmNoSuffix
+	call	parseDecimalDigit
+	jr	c, .pmNoSuffix
+	call	.parseDecimalM	; --> DE
+.pmNoSuffix:
+	pop	af		; bring back that +/-
+	cp	'-'
+	jr	nz, .end
+	; we had a "-". Negate DE
+	push	hl
+	ld	hl, 0
+	sbc	hl, de
+	ex	de, hl
+	pop	hl
+.end:
+	; We expect HL (rest of the cmdline) to be a null char, otherwise it's
+	; garbage
+	ld	a, (hl)
+	or	a
+	ret	nz
+	; we still have to save DE in memory
+	ld	(ix+1), e
+	ld	(ix+2), d
+	ret
+
+; call parseDecimal and set HL to the character following the last digit
+.parseDecimalM:
+	push	bc
+	push	ix
+	push	hl
+.loop:
+	inc	hl
+	ld	a, (hl)
+	call	parseDecimalDigit
+	jr	nc, .loop
+	; We're at the first non-digit char. Let's save it because we're going
+	; to temporarily replace it with a null.
+	ld	b, a
+	xor	a
+	ld	(hl), a
+	; Now, let's go back to the beginning of the string and parse it.
+	; but before we do this, let's save the end of string in DE
+	ex	de, hl
+	pop	hl
+	call	parseDecimal
+	; Z is set properly at this point. nothing touches Z below.
+	ld	a, b
+	ld	(de), a
+	ex	de, hl	; put end of string back from DE to HL
+	; Put addr in its final register, DE
+	push	ix \ pop de
+	pop	ix
+	pop	bc
+	ret
+
+; Make (IX) point to addr 1
+cmdAddr1:
+	ld	ix, CMD_ADDR1
+	ret
+
+; Set A to CMD_TYPE
+cmdType:
+	ld	a, (CMD_TYPE)
+	ret

apps/ed/glue.asm

@@ -9,6 +9,8 @@
 #include "ed/io.asm"
 .equ	BUF_RAMSTART	IO_RAMEND
 #include "ed/buf.asm"
-.equ	ED_RAMSTART	BUF_RAMEND
+.equ	CMD_RAMSTART	BUF_RAMEND
+#include "ed/cmd.asm"
+.equ	ED_RAMSTART	CMD_RAMEND
 #include "ed/main.asm"
 

apps/ed/main.asm

@@ -86,118 +86,43 @@ edMain:
 	; We're done. Process line.
 	call	printcrlf
 	call	stdioGetLine
-	call	.processLine
+	call	cmdParse
-	ret	z
+	jr	nz, .error
-	jr	.mainLoop
+	call	cmdType
-
-; Sets Z if we need to quit
-.processLine:
-	ld	a, (hl)
 	cp	'q'
 	ret	z
-	call	edReadAddr
+	jr	.doPrint
-	jr	z, .processNumber
+
-	jr	.processError
+.doPrint:
-.processNumber:
+	call	cmdAddr1
-	; number is in DE
+	call	edResolveAddr
-	; We expect HL (rest of the cmdline) to be a null char, otherwise it's
-	; garbage
-	ld	a, (hl)
-	or	a
-	jr	nz, .processError
-	ex	de, hl
 	ld	(ED_CURLINE), hl
 	call	bufGetLine
-	jr	nz, .processError
+	jr	nz, .error
 	call	printstr
 	call	printcrlf
-	; continue to end
+	jr	.mainLoop
-.processEnd:
+.error:
-	call	printcrlf
-	jp	unsetZ
-.processError:
 	ld	a, '?'
 	call	stdioPutC
 	call	printcrlf
-	jp	unsetZ
+	jr	.mainLoop
 
-; Parse the string at (HL) and sets its corresponding address in DE, properly
+
-; considering implicit values (current address when nothing is specified).
+; Transform an address "cmd" in IX into an absolute address in HL.
-; advances HL to the char next to the last parsed char.
+edResolveAddr:
-; It handles "+" and "-" addresses such as "+3", "-2", "+", "-".
+	ld	a, (ix)
-; Sets Z on success, unset on error. Line out of bounds isn't an error. Only
+	cp	RELATIVE
-; overflows.
+	jr	z, .relative
-edReadAddr:
+	; absolute
-	ld	a, (hl)
+	ld	l, (ix+1)
-	cp	'+'
+	ld	a, l
-	jr	z, .plusOrMinus
+	ld	h, (ix+2)
-	cp	'-'
-	jr	z, .plusOrMinus
-	call	parseDecimalDigit
-	jr	c, .notHandled
-	; straight number
-	call	.parseDecimalM	; Z has proper value
-	dec	de	; from 1-based to 0-base. 16bit doesn't affect flags.
 	ret
-.notHandled:
+.relative:
-	; something else. Something we don't handle. Our addr is therefore
-	; (ED_CURLINE).
-	push	hl
 	ld	hl, (ED_CURLINE)
-	ex	de, hl
+	ld	e, (ix+1)
-	pop	hl
+	ld	d, (ix+2)
-	cp	a		; ensure Z
-	ret
-.plusOrMinus:
-	push	af		; preserve that + or -
-	inc	hl		; advance cmd cursor
-	ld	a, (hl)
-	ld	de, 1		; if .pmNoSuffix
-	call	parseDecimalDigit
-	jr	c, .pmNoSuffix
-	call	.parseDecimalM	; --> DE
-.pmNoSuffix:
-	pop	af		; bring back that +/-
-	push	hl
-	ld	hl, (ED_CURLINE)
-	cp	'-'
-	jr	z, .pmIsMinus
 	add	hl, de
-	jr	.pmEnd
-.pmIsMinus:
-	sbc	hl, de
-.pmEnd:
-	ex	de, hl
-	pop	hl
-	cp	a		; ensure Z
 	ret
 
-; call parseDecimal and set HL to the character following the last digit
-.parseDecimalM:
-	push	bc
-	push	ix
-	push	hl
-.loop:
-	inc	hl
-	ld	a, (hl)
-	call	parseDecimalDigit
-	jr	nc, .loop
-	; We're at the first non-digit char. Let's save it because we're going
-	; to temporarily replace it with a null.
-	ld	b, a
-	xor	a
-	ld	(hl), a
-	; Now, let's go back to the beginning of the string and parse it.
-	; but before we do this, let's save the end of string in DE
-	ex	de, hl
-	pop	hl
-	call	parseDecimal
-	; Z is set properly at this point. nothing touches Z below.
-	ld	a, b
-	ld	(de), a
-	ex	de, hl	; put end of string back from DE to HL
-	; Put addr in its final register, DE
-	push	ix \ pop de
-	pop	ix
-	pop	bc
-	ret