1 files changed, 38 insertions, 0 deletions
diff --git a/src/home/math.asm b/src/home/math.asm
new file mode 100644
index 0000000..8e54cb8
--- /dev/null
+++ b/src/home/math.asm
@@ -0,0 +1,38 @@
+; returns a *= 10
+ATimes10:
+	push de
+	ld e, a
+	add a
+	add a
+	add e
+	add a
+	pop de
+	ret
+
+; returns hl *= 10
+HLTimes10:
+	push de
+	ld l, a
+	ld e, a
+	ld h, $00
+	ld d, h
+	add hl, hl
+	add hl, hl
+	add hl, de
+	add hl, hl
+	pop de
+	ret
+
+; returns a /= 10
+; returns carry if a % 10 >= 5
+ADividedBy10:
+	push de
+	ld e, -1
+.asm_c62
+	inc e
+	sub 10
+	jr nc, .asm_c62
+	add 5
+	ld a, e
+	pop de
+	ret