lib/expr: add division and modulo operators

apps/README.md

@@ -89,8 +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. For
+An expression is a bunch of literals or symbols assembled by operators.
-now, only `+`, `-` and `*` operators are supported. No parenthesis yet.
+Supported operators are `+`, `-`, `*`, `/` and `%` (modulo). 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

@@ -113,6 +113,10 @@ exprTbl:
 	.dw	.minus
 	.db	'*'
 	.dw	.mult
+	.db	'/'
+	.dw	.div
+	.db	'%'
+	.dw	.mod
 	.db	0		; end of table
 
 .plus:
@@ -137,3 +141,19 @@ exprTbl:
 	push	hl \ pop ix
 	cp	a		; ensure Z
 	ret
+
+.div:
+	; divide takes HL/DE
+	push	bc
+	ex	de, hl
+	push	ix \ pop de
+	call	divide
+	push	bc \ pop ix
+	pop	bc
+	cp	a		; ensure Z
+	ret
+
+.mod:
+	call	.div
+	push	hl \ pop	ix
+	ret

tools/tests/unit/test_expr.asm

@@ -42,9 +42,9 @@ sFOO:		.db "FOO", 0
 sBAR:		.db "BAR", 0
 
 test:
-	ld	hl, 0xffff
+	ld	sp, 0xffff
-	ld	sp, hl
 
+	; Old-style tests, not touching them now.
 	ld	hl, s1
 	call	parseExpr
 	jp	nz, fail
@@ -128,10 +128,40 @@ 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
+	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
+
 nexttest:
 	ld	a, (testNum)
 	inc	a