basic: parse hex, binary and char literals

Same thing as in zasm.

CODE.md

@@ -46,6 +46,11 @@ Another exception to this rule are "top-level" routines, that is, routines that
 aren't designed to be called from other parts of Collapse OS. Those are
 generally routines close to an application's main loop.
 
+It is important to note, however, that shadow registers aren't preserved.
+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.
+
 ## Stack management
 
 Keeping the stack "balanced" is a big challenge when writing assembler code.

apps/basic/main.asm

@@ -105,7 +105,7 @@ basBYE:
 	.db	"Goodbye!", 0
 
 basPRINT:
-	call	parseDecimal
+	call	parseLiteral
 	jp	nz, basERR
 	push	ix \ pop de
 	ld	hl, BAS_SCRATCHPAD

apps/lib/parse.asm

@@ -136,3 +136,168 @@ parseDecimal:
 .error:
 	pop	hl
 	jp	unsetZ
+
+; Parse string at (HL) as a hexadecimal value and return value in IX under the
+; same conditions as parseLiteral.
+parseHexadecimal:
+	call	hasHexPrefix
+	ret	nz
+	push	hl
+	push	de
+	ld	d, 0
+	inc	hl	; get rid of "0x"
+	inc	hl
+	call	strlen
+	cp	3
+	jr	c, .single
+	cp	4
+	jr	c, .doubleShort	; 0x123
+	cp	5
+	jr	c, .double	; 0x1234
+	; too long, error
+	jr	.error
+.double:
+	call	parseHexPair
+	jr	c, .error
+	inc	hl			; now HL is on first char of next pair
+	ld	d, a
+	jr	.single
+.doubleShort:
+	ld	a, (hl)
+	call	parseHex
+	jr	c, .error
+	inc	hl			; now HL is on first char of next pair
+	ld	d, a
+.single:
+	call	parseHexPair
+	jr	c, .error
+	ld	e, a
+	cp	a			; ensure Z
+	jr	.end
+.error:
+	call	unsetZ
+.end:
+	push	de \ pop ix
+	pop	de
+	pop	hl
+	ret
+
+; Sets Z if (HL) has a '0x' prefix.
+hasHexPrefix:
+	ld	a, (hl)
+	cp	'0'
+	ret	nz
+	push	hl
+	inc	hl
+	ld	a, (hl)
+	cp	'x'
+	pop	hl
+	ret
+
+; Parse string at (HL) as a binary value (0b010101) and return value in IX.
+; High IX byte is always clear.
+; Sets Z on success.
+parseBinaryLiteral:
+	call	hasBinPrefix
+	ret	nz
+	push	bc
+	push	hl
+	push	de
+	ld	d, 0
+	inc	hl	; get rid of "0b"
+	inc	hl
+	call	strlen
+	or	a
+	jr	z, .error	; empty, error
+	cp	9
+	jr	nc, .error	; >= 9, too long
+	; We have a string of 8 or less chars. What we'll do is that for each
+	; char, we rotate left and set the LSB according to whether we have '0'
+	; or '1'. Error out on anything else. C is our stored result.
+	ld	b, a		; we loop for "strlen" times
+	ld	c, 0		; our stored result
+.loop:
+	rlc	c
+	ld	a, (hl)
+	inc	hl
+	cp	'0'
+	jr	z, .nobit	; no bit to set
+	cp	'1'
+	jr	nz, .error	; not 0 or 1
+	; We have a bit to set
+	inc	c
+.nobit:
+	djnz	.loop
+	ld	e, c
+	cp	a		; ensure Z
+	jr	.end
+.error:
+	call	unsetZ
+.end:
+	push	de \ pop ix
+	pop	de
+	pop	hl
+	pop	bc
+	ret
+
+; Sets Z if (HL) has a '0b' prefix.
+hasBinPrefix:
+	ld	a, (hl)
+	cp	'0'
+	ret	nz
+	push	hl
+	inc	hl
+	ld	a, (hl)
+	cp	'b'
+	pop	hl
+	ret
+
+; Parse string at (HL) and, if it is a char literal, sets Z and return
+; corresponding value in IX. High IX byte is always clear.
+;
+; A valid char literal starts with ', ends with ' and has one character in the
+; middle. No escape sequence are accepted, but ''' will return the apostrophe
+; character.
+parseCharLiteral:
+	ld	a, 0x27		; apostrophe (') char
+	cp	(hl)
+	ret	nz
+
+	push	hl
+	push	de
+	inc	hl
+	inc	hl
+	cp	(hl)
+	jr	nz, .end	; not ending with an apostrophe
+	inc	hl
+	ld	a, (hl)
+	or	a		; cp 0
+	jr	nz, .end	; string has to end there
+	; Valid char, good
+	ld	d, a		; A is zero, take advantage of that
+	dec	hl
+	dec	hl
+	ld	a, (hl)
+	ld	e, a
+	cp	a		; ensure Z
+.end:
+	push	de \ pop ix
+	pop	de
+	pop	hl
+	ret
+
+; Parses the string at (HL) and returns the 16-bit value in IX. The string
+; can be a decimal literal (1234), a hexadecimal literal (0x1234) or a char
+; literal ('X').
+;
+; As soon as the number doesn't fit 16-bit any more, parsing stops and the
+; number is invalid. If the number is valid, Z is set, otherwise, unset.
+parseLiteral:
+	call	parseCharLiteral
+	ret	z
+	call	parseHexadecimal
+	ret	z
+	call	parseBinaryLiteral
+	ret	z
+	jp	parseDecimal
+

apps/lib/util.asm

@@ -52,3 +52,25 @@ strcmp:
 	; early, set otherwise)
 	ret
 
+; Returns length of string at (HL) in A.
+; Doesn't include null termination.
+strlen:
+	push	bc
+	push	hl
+	ld	bc, 0
+	xor	a	; look for null char
+.loop:
+	cpi
+	jp	z, .found
+	jr	.loop
+.found:
+	; How many char do we have? the (NEG BC)-1, which started at 0 and
+	; decreased at each CPI call. In this routine, we stay in the 8-bit
+	; realm, so C only.
+	ld	a, c
+	neg
+	dec	a
+	pop	hl
+	pop	bc
+	ret
+

apps/zasm/parse.asm

@@ -1,167 +1,3 @@
-; Parse string at (HL) as a hexadecimal value and return value in IX under the
-; same conditions as parseLiteral.
-parseHexadecimal:
-	call	hasHexPrefix
-	ret	nz
-	push	hl
-	push	de
-	ld	d, 0
-	inc	hl	; get rid of "0x"
-	inc	hl
-	call	strlen
-	cp	3
-	jr	c, .single
-	cp	4
-	jr	c, .doubleShort	; 0x123
-	cp	5
-	jr	c, .double	; 0x1234
-	; too long, error
-	jr	.error
-.double:
-	call	parseHexPair
-	jr	c, .error
-	inc	hl			; now HL is on first char of next pair
-	ld	d, a
-	jr	.single
-.doubleShort:
-	ld	a, (hl)
-	call	parseHex
-	jr	c, .error
-	inc	hl			; now HL is on first char of next pair
-	ld	d, a
-.single:
-	call	parseHexPair
-	jr	c, .error
-	ld	e, a
-	cp	a			; ensure Z
-	jr	.end
-.error:
-	call	unsetZ
-.end:
-	push	de \ pop ix
-	pop	de
-	pop	hl
-	ret
-
-; Sets Z if (HL) has a '0x' prefix.
-hasHexPrefix:
-	ld	a, (hl)
-	cp	'0'
-	ret	nz
-	push	hl
-	inc	hl
-	ld	a, (hl)
-	cp	'x'
-	pop	hl
-	ret
-
-; Parse string at (HL) as a binary value (0b010101) and return value in IX.
-; High IX byte is always clear.
-; Sets Z on success.
-parseBinaryLiteral:
-	call	hasBinPrefix
-	ret	nz
-	push	bc
-	push	hl
-	push	de
-	ld	d, 0
-	inc	hl	; get rid of "0b"
-	inc	hl
-	call	strlen
-	or	a
-	jr	z, .error	; empty, error
-	cp	9
-	jr	nc, .error	; >= 9, too long
-	; We have a string of 8 or less chars. What we'll do is that for each
-	; char, we rotate left and set the LSB according to whether we have '0'
-	; or '1'. Error out on anything else. C is our stored result.
-	ld	b, a		; we loop for "strlen" times
-	ld	c, 0		; our stored result
-.loop:
-	rlc	c
-	ld	a, (hl)
-	inc	hl
-	cp	'0'
-	jr	z, .nobit	; no bit to set
-	cp	'1'
-	jr	nz, .error	; not 0 or 1
-	; We have a bit to set
-	inc	c
-.nobit:
-	djnz	.loop
-	ld	e, c
-	cp	a		; ensure Z
-	jr	.end
-.error:
-	call	unsetZ
-.end:
-	push	de \ pop ix
-	pop	de
-	pop	hl
-	pop	bc
-	ret
-
-; Sets Z if (HL) has a '0b' prefix.
-hasBinPrefix:
-	ld	a, (hl)
-	cp	'0'
-	ret	nz
-	push	hl
-	inc	hl
-	ld	a, (hl)
-	cp	'b'
-	pop	hl
-	ret
-
-; Parse string at (HL) and, if it is a char literal, sets Z and return
-; corresponding value in IX. High IX byte is always clear.
-;
-; A valid char literal starts with ', ends with ' and has one character in the
-; middle. No escape sequence are accepted, but ''' will return the apostrophe
-; character.
-parseCharLiteral:
-	ld	a, 0x27		; apostrophe (') char
-	cp	(hl)
-	ret	nz
-
-	push	hl
-	push	de
-	inc	hl
-	inc	hl
-	cp	(hl)
-	jr	nz, .end	; not ending with an apostrophe
-	inc	hl
-	ld	a, (hl)
-	or	a		; cp 0
-	jr	nz, .end	; string has to end there
-	; Valid char, good
-	ld	d, a		; A is zero, take advantage of that
-	dec	hl
-	dec	hl
-	ld	a, (hl)
-	ld	e, a
-	cp	a		; ensure Z
-.end:
-	push	de \ pop ix
-	pop	de
-	pop	hl
-	ret
-
-; Parses the string at (HL) and returns the 16-bit value in IX. The string
-; can be a decimal literal (1234), a hexadecimal literal (0x1234) or a char
-; literal ('X').
-;
-; As soon as the number doesn't fit 16-bit any more, parsing stops and the
-; number is invalid. If the number is valid, Z is set, otherwise, unset.
-parseLiteral:
-	call	parseCharLiteral
-	ret	z
-	call	parseHexadecimal
-	ret	z
-	call	parseBinaryLiteral
-	ret	z
-	jp	parseDecimal
-
 ; Parse string in (HL) and return its numerical value whether its a number
 ; literal or a symbol. Returns value in IX.
 ; Sets Z if number or symbol is valid, unset otherwise.

apps/zasm/util.asm

@@ -30,28 +30,6 @@ toggleZ:
 	cp	a
 	ret
 
-; Returns length of string at (HL) in A.
-; Doesn't include null termination.
-strlen:
-	push	bc
-	push	hl
-	ld	bc, 0
-	ld	a, 0	; look for null char
-.loop:
-	cpi
-	jp	z, .found
-	jr	.loop
-.found:
-	; How many char do we have? the (NEG BC)-1, which started at 0 and
-	; decreased at each CPI call. In this routine, we stay in the 8-bit
-	; realm, so C only.
-	ld	a, c
-	neg
-	dec	a
-	pop	hl
-	pop	bc
-	ret
-
 ; Sets Z if string at (HL) is one character long
 strIs1L:
 	xor	a

tools/tests/unit/test_util_z.asm

@@ -2,6 +2,7 @@ jp	test
 
 .inc "core.asm"
 .inc "str.asm"
+.inc "lib/util.asm"
 .inc "zasm/util.asm"
 
 testNum:	.db 1