From 1b01f131057fdf45f299aab07d15efdb60545c97 Mon Sep 17 00:00:00 2001
From: Virgil Dupras <hsoft@hardcoded.net>
Date: Fri, 22 Nov 2019 14:45:12 -0500
Subject: [PATCH] lib/expr: refactor for easier operator addition

---
 apps/lib/ari.asm                      | 17 ++++++++++
 apps/lib/expr.asm                     | 61 ++++++++++++++++++++++-------------
 apps/lib/util.asm                     | 17 ----------
 apps/zasm/glue.asm                    |  1 +
 tools/tests/unit/test_basic_parse.asm |  1 +
 tools/tests/unit/test_expr.asm        |  1 +
 tools/tests/unit/test_lib_ari.asm     | 35 ++++++++++++++++++++
 tools/tests/unit/test_util_z.asm      |  8 -----
 tools/tests/unit/test_z_instr.asm     |  1 +
 9 files changed, 95 insertions(+), 47 deletions(-)
 create mode 100644 tools/tests/unit/test_lib_ari.asm

diff --git a/apps/lib/ari.asm b/apps/lib/ari.asm
index b5ade17..8f40838 100644
--- a/apps/lib/ari.asm
+++ b/apps/lib/ari.asm
@@ -25,3 +25,20 @@ divide:
 	sbc a, d
 	ld h, a
 	ret
+
+; DE * BC -> DE (high) and HL (low)
+multDEBC:
+	ld	hl, 0
+	ld	a, 0x10
+.loop:
+	add	hl, hl
+	rl	e
+	rl	d
+	jr	nc, .noinc
+	add	hl, bc
+	jr	nc, .noinc
+	inc	de
+.noinc:
+	dec a
+	jr	nz, .loop
+	ret
diff --git a/apps/lib/expr.asm b/apps/lib/expr.asm
index ce8f1b5..e144d46 100644
--- a/apps/lib/expr.asm
+++ b/apps/lib/expr.asm
@@ -23,16 +23,30 @@ parseExpr:
 	ret
 
 _parseExpr:
-	ld	a, '+'
+	ld	de, exprTbl
+.loop:
+	ld	a, (de)
+	or	a
+	jp	z, EXPR_PARSE	; no operator, just parse the literal
+	push	de		; --> lvl 1. save operator row
 	call	_findAndSplit
-	jp	z, _applyPlus
-	ld	a, '-'
-	call	_findAndSplit
-	jp	z, _applyMinus
-	ld	a, '*'
-	call	_findAndSplit
-	jp	z, _applyMult
-	jp	EXPR_PARSE
+	jr	z, .found
+	pop	de		; <-- lvl 1
+	inc	de \ inc de \ inc de
+	jr	.loop
+.found:
+	; 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 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	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
@@ -88,20 +102,25 @@ _resolveLeftAndRight:
 	pop	de	; numeric left expr result in DE
 	jp	parseExpr
 
-; Parse expr in (HL) and expr in (DE) and apply + operator to both sides.
-; Put result in IX.
-_applyPlus:
-	call	_resolveLeftAndRight
-	ret	nz
-	; Good! let's do the math! IX has our right part, DE has our left one.
+; 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 IX.
+; The table has 3 bytes per row: 1 byte for operator and 2 bytes for routine
+; pointer.
+exprTbl:
+	.db	'+'
+	.dw	.plus
+	.db	'-'
+	.dw	.minus
+	.db	'*'
+	.dw	.mult
+	.db	0		; end of table
+
+.plus:
 	add	ix, de
 	cp	a		; ensure Z
 	ret
 
-; Same as _applyPlus but with -
-_applyMinus:
-	call	_resolveLeftAndRight
-	ret	nz
+.minus:
 	push	ix
 	pop	hl
 	ex	de, hl
@@ -112,9 +131,7 @@ _applyMinus:
 	cp	a		; ensure Z
 	ret
 
-_applyMult:
-	call	_resolveLeftAndRight
-	ret	nz
+.mult:
 	push	ix \ pop bc
 	call	multDEBC
 	push	hl \ pop ix
diff --git a/apps/lib/util.asm b/apps/lib/util.asm
index b5be841..3cad42a 100644
--- a/apps/lib/util.asm
+++ b/apps/lib/util.asm
@@ -73,20 +73,3 @@ strlen:
 	pop	hl
 	pop	bc
 	ret
-
-; DE * BC -> DE (high) and HL (low)
-multDEBC:
-	ld	hl, 0
-	ld	a, 0x10
-.loop:
-	add	hl, hl
-	rl	e
-	rl	d
-	jr	nc, .noinc
-	add	hl, bc
-	jr	nc, .noinc
-	inc	de
-.noinc:
-	dec a
-	jr	nz, .loop
-	ret
diff --git a/apps/zasm/glue.asm b/apps/zasm/glue.asm
index f577ff6..291df8c 100644
--- a/apps/zasm/glue.asm
+++ b/apps/zasm/glue.asm
@@ -66,6 +66,7 @@ jp	zasmMain
 .inc "core.asm"
 .inc "zasm/const.asm"
 .inc "lib/util.asm"
+.inc "lib/ari.asm"
 .inc "lib/parse.asm"
 .inc "lib/args.asm"
 .inc "zasm/util.asm"
diff --git a/tools/tests/unit/test_basic_parse.asm b/tools/tests/unit/test_basic_parse.asm
index 5bf0dab..6949da5 100644
--- a/tools/tests/unit/test_basic_parse.asm
+++ b/tools/tests/unit/test_basic_parse.asm
@@ -3,6 +3,7 @@ jp	test
 .inc "core.asm"
 .inc "str.asm"
 .inc "lib/util.asm"
+.inc "lib/ari.asm"
 .inc "lib/parse.asm"
 .equ	EXPR_PARSE	parseLiteral
 .inc "lib/expr.asm"
diff --git a/tools/tests/unit/test_expr.asm b/tools/tests/unit/test_expr.asm
index 5b580cf..a906ad5 100644
--- a/tools/tests/unit/test_expr.asm
+++ b/tools/tests/unit/test_expr.asm
@@ -12,6 +12,7 @@ jp	test
 .inc "core.asm"
 .inc "str.asm"
 .inc "lib/util.asm"
+.inc "lib/ari.asm"
 .inc "zasm/util.asm"
 .inc "zasm/const.asm"
 .inc "lib/parse.asm"
diff --git a/tools/tests/unit/test_lib_ari.asm b/tools/tests/unit/test_lib_ari.asm
new file mode 100644
index 0000000..b81ba28
--- /dev/null
+++ b/tools/tests/unit/test_lib_ari.asm
@@ -0,0 +1,35 @@
+jp	test
+
+.inc "core.asm"
+.inc "lib/ari.asm"
+
+testNum:	.db 1
+
+test:
+	ld	sp, 0xffff
+
+	ld	de, 12
+	ld	bc, 4
+	call	multDEBC
+	ld	a, l
+	cp	48
+	jp	nz, fail
+	call	nexttest
+
+	; success
+	xor	a
+	halt
+
+nexttest:
+	ld	a, (testNum)
+	inc	a
+	ld	(testNum), a
+	ret
+
+fail:
+	ld	a, (testNum)
+	halt
+
+
+
+
diff --git a/tools/tests/unit/test_util_z.asm b/tools/tests/unit/test_util_z.asm
index 7dfd10d..fd461f0 100644
--- a/tools/tests/unit/test_util_z.asm
+++ b/tools/tests/unit/test_util_z.asm
@@ -12,14 +12,6 @@ test:
 	ld	hl, 0xffff
 	ld	sp, hl
 
-	ld	de, 12
-	ld	bc, 4
-	call	multDEBC
-	ld	a, l
-	cp	48
-	jp	nz, fail
-	call	nexttest
-
 	ld	hl, sFoo
 	call	strlen
 	cp	3
diff --git a/tools/tests/unit/test_z_instr.asm b/tools/tests/unit/test_z_instr.asm
index 04d2248..96bf755 100644
--- a/tools/tests/unit/test_z_instr.asm
+++ b/tools/tests/unit/test_z_instr.asm
@@ -4,6 +4,7 @@ jp	runTests
 .inc "core.asm"
 .inc "str.asm"
 .inc "zasm/const.asm"
+.inc "lib/ari.asm"
 .inc "lib/util.asm"
 .inc "zasm/util.asm"
 .inc "lib/parse.asm"