apps/README.md

@@ -89,16 +89,8 @@ this way, it's going to mess with the parser.
 
 ### Expressions
 
-An expression is a bunch of literals or symbols assembled by operators.
-Supported operators are `+`, `-`, `*`, `/`, `%` (modulo), `&` (bitwise and),
-`|` (bitwise or), `^` (bitwise xor), `{` (shift left), `}` (shift right).
-Bitwise operator always operate on the whole 16-bits.
-
-Shift operators break from the `<<` and `>>` tradition because the complexity
-if two-sized operator is significant and deemed not worth it. The shift
-operator shift the left operand X times, X being the right operand.
-
-There is no parenthesis support yet.
+An expression is a bunch of literals or symbols assembled by operators. For
+now, only `+`, `-` and `*` operators are supported. No parenthesis yet.
 
 Symbols have a different meaning depending on the application. In zasm, it's
 labels and constants. In basic, it's variables.

apps/lib/expr.asm

@@ -1,7 +1,6 @@
 ; *** Requirements ***
 ; findchar
 ; multDEBC
-; callIXI
 ;
 ; *** Defines ***
 ;
@@ -15,9 +14,6 @@
 ; **This routine mutates (HL).**
 ; We expect (HL) to be disposable: we mutate it to avoid having to make a copy.
 ; Sets Z on success, unset on error.
-; TODO: the IX output register is a bit awkward. Nearly everywhere, I need
-;       to push \ pop that thing. See if we could return the result in DE
-;       instead.
 parseExpr:
 	push	de
 	push	hl
@@ -42,16 +38,15 @@ _parseExpr:
 	; Operator found, string splitted. Left in (HL), right in (DE)
 	call	_resolveLeftAndRight
 	; Whether _resolveLeftAndRight was a success, we pop our lvl 1 stack
-	; out, which contains our operator row. We pop it in IX.
-	; L-R numbers are parsed in HL (left) and DE (right).
-	pop	ix		; <-- lvl 1
+	; out, which contains our operator row. We pop it in HL because we
+	; don't need our string anymore. L-R numbers are parsed, and in DE and
+	; IX.
+	pop	hl		; <-- lvl 1
 	ret	nz
 	; Resolving left and right succeeded, proceed!
-	inc	ix		; point to routine pointer
-	call	callIXI
-	push	de \ pop ix
-	cp	a		; ensure Z
-	ret
+	inc	hl		; point to routine pointer
+	call	intoHL
+	jp	(hl)
 
 ; Given a string in (HL) and a separator char in A, return a splitted string,
 ; that is, the same (HL) string but with the found A char replaced by a null
@@ -95,7 +90,7 @@ _findAndSplit:
 .find:
 
 ; parse expression on the left (HL) and the right (DE) and put the results in
-; HL (left) and DE (right)
+; DE (left) and IX (right)
 _resolveLeftAndRight:
 	call	parseExpr
 	ret	nz		; return immediately if error
@@ -103,14 +98,12 @@ _resolveLeftAndRight:
 	; IX. What we need to do now is the same thing on (DE) and then apply
 	; the + operator. Let's save IX somewhere and parse this.
 	ex	de, hl	; right expr now in HL
-	push	ix	; --> lvl 1
-	call	parseExpr
-	pop	hl	; <-- lvl 1. left
-	push	ix \ pop de	; right
-	ret		; Z is parseExpr's result
+	push	ix
+	pop	de	; numeric left expr result in DE
+	jp	parseExpr
 
 ; Routines in here all have the same signature: they take two numbers, DE (left)
-; and IX (right), apply the operator and put the resulting number in DE.
+; and IX (right), apply the operator and put the resulting number in IX.
 ; The table has 3 bytes per row: 1 byte for operator and 2 bytes for routine
 ; pointer.
 exprTbl:
@@ -120,104 +113,27 @@ exprTbl:
 	.dw	.minus
 	.db	'*'
 	.dw	.mult
-	.db	'/'
-	.dw	.div
-	.db	'%'
-	.dw	.mod
-	.db	'&'
-	.dw	.and
-	.db	0x7c		; '|'
-	.dw	.or
-	.db	'^'
-	.dw	.xor
-	.db	'}'
-	.dw	.rshift
-	.db	'{'
-	.dw	.lshift
 	.db	0		; end of table
 
 .plus:
-	add	hl, de
-	ex	de, hl
+	add	ix, de
+	cp	a		; ensure Z
 	ret
 
 .minus:
-	or	a	; clear carry
-	sbc	hl, de
+	push	ix
+	pop	hl
 	ex	de, hl
+	scf \ ccf
+	sbc	hl, de
+	push	hl
+	pop	ix
+	cp	a		; ensure Z
 	ret
 
 .mult:
-	ld	b, h
-	ld	c, l
-	call	multDEBC	; --> HL
-	ex	de, hl
-	ret
-
-.div:
-	; divide takes HL/DE
-	push	bc
-	call	divide
-	ld	e, c
-	ld	d, b
-	pop	bc
-	ret
-
-.mod:
-	call	.div
-	ex	de, hl
-	ret
-
-.and:
-	ld	a, h
-	and	d
-	ld	d, a
-	ld	a, l
-	and	e
-	ld	e, a
-	ret
-.or:
-	ld	a, h
-	or	d
-	ld	d, a
-	ld	a, l
-	or	e
-	ld	e, a
-	ret
-
-.xor:
-	ld	a, h
-	xor	d
-	ld	d, a
-	ld	a, l
-	xor	e
-	ld	e, a
-	ret
-
-.rshift:
-	ld	a, e
-	and	0xf
-	ret	z
-	push	bc
-	ld	b, a
-.rshiftLoop:
-	srl	h
-	rr	l
-	djnz	.rshiftLoop
-	ex	de, hl
-	pop	bc
-	ret
-
-.lshift:
-	ld	a, e
-	and	0xf
-	ret	z
-	push	bc
-	ld	b, a
-.lshiftLoop:
-	sla	l
-	rl	h
-	djnz	.lshiftLoop
-	ex	de, hl
-	pop	bc
+	push	ix \ pop bc
+	call	multDEBC
+	push	hl \ pop ix
+	cp	a		; ensure Z
 	ret

tools/tests/unit/test_expr.asm

@@ -42,9 +42,9 @@ sFOO:		.db "FOO", 0
 sBAR:		.db "BAR", 0
 
 test:
-	ld	sp, 0xffff
+	ld	hl, 0xffff
+	ld	sp, hl
 
-	; Old-style tests, not touching them now.
 	ld	hl, s1
 	call	parseExpr
 	jp	nz, fail
@@ -128,65 +128,10 @@ test:
 	jp	nz, fail
 	call	nexttest
 
-	; New-style tests
-	call	testParseExpr
 	; success
 	xor	a
 	halt
 
-testParseExpr:
-	ld	iy, .t1
-	call	.testEQ
-	ld	iy, .t2
-	call	.testEQ
-	ld	iy, .t3
-	call	.testEQ
-	ld	iy, .t4
-	call	.testEQ
-	ld	iy, .t5
-	call	.testEQ
-	ld	iy, .t6
-	call	.testEQ
-	ld	iy, .t7
-	call	.testEQ
-	ret
-
-.testEQ:
-	push	iy \ pop hl
-	inc	hl \ inc hl
-	call	parseExpr
-	jp	nz, fail
-	push	ix \ pop de
-	ld	a, e
-	cp	(iy)
-	jp	nz, fail
-	ld	a, d
-	cp	(iy+1)
-	jp	nz, fail
-	jp	nexttest
-
-.t1:
-	.dw	7
-	.db	"42/6", 0
-.t2:
-	.dw	1
-	.db	"7%3", 0
-.t3:
-	.dw	0x0907
-	.db	"0x99f7&0x0f0f", 0
-.t4:
-	.dw	0x9fff
-	.db	"0x99f7|0x0f0f", 0
-.t5:
-	.dw	0x96f8
-	.db	"0x99f7^0x0f0f", 0
-.t6:
-	.dw	0x133e
-	.db	"0x99f7}3", 0
-.t7:
-	.dw	0xcfb8
-	.db	"0x99f7{3", 0
-
 nexttest:
 	ld	a, (testNum)
 	inc	a