zasm: add support for "0b" literals

apps/zasm/parse_z.asm

@@ -93,7 +93,7 @@ parseHexadecimal:
 	pop	hl
 	ret
 
-; Sets Z if (HL) has a '0x' or '0X' prefix.
+; Sets Z if (HL) has a '0x' prefix.
 hasHexPrefix:
 	ld	a, (hl)
 	cp	'0'
@@ -105,6 +105,62 @@ hasHexPrefix:
 	pop	hl
 	ret
 
+; Parse string at (HL) as a binary value (0b010101) and return value in IXL.
+; Clears IXH.
+; Sets Z on success.
+parseBinaryLiteral:
+	call	hasBinPrefix
+	ret	nz
+	push	bc
+	push	hl
+	xor	a
+	ld	ixh, a
+	inc	hl	; get rid of "0x"
+	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	ixl, c
+	cp	a		; ensure Z
+	jr	.end
+.error:
+	call	unsetZ
+.end:
+	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 IXL. Clears IXH.
 ;
@@ -147,6 +203,8 @@ parseLiteral:
 	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

tools/tests/unit/test_parse_z.asm

@@ -16,6 +16,8 @@ testNum:	.db 1
 
 s99:		.db "99", 0
 s0x99:		.db "0x99", 0
+s0b0101:	.db "0b0101", 0
+s0b01010101:	.db "0b01010101", 0
 sFoo:		.db "Foo", 0
 
 test:
@@ -38,6 +40,28 @@ test:
 	jp	z, fail
 	call	nexttest
 
+	ld	hl, s0b0101
+	call	parseLiteral
+	jp	nz, fail
+	ld	a, ixh
+	or	a
+	jp	nz, fail
+	ld	a, ixl
+	cp	0b0101
+	jp	nz, fail
+	call	nexttest
+
+	ld	hl, s0b01010101
+	call	parseLiteral
+	jp	nz, fail
+	ld	a, ixh
+	or	a
+	jp	nz, fail
+	ld	a, ixl
+	cp	0b01010101
+	jp	nz, fail
+	call	nexttest
+
 	; success
 	xor	a
 	halt