From: Lukas Krickl <lukas@krickl.dev>
Date: Sun, 1 Feb 2026 07:31:37 +0000 (+0100)
Subject: math: Addd 16 bit add
X-Git-Url: https://git.krickl.dev/?a=commitdiff_plain;h=abdc88d02a935c8b139399150e0552c1503519bd;p=gbrg%2F.git

math: Addd 16 bit add

Added macros for storing math registers
---

diff --git a/src/math.s b/src/math.s
index 8231515..22e0f64 100644
--- a/src/math.s
+++ b/src/math.s
@@ -1,10 +1,49 @@
 
+	; writes a 16 bit register
+	; to an m16 regsiter
+	; inputs:
+	;		$1: m16_a/b
+#macro m16_write_bc
+	ld a, c
+	ld [$1], a
+	ld a, b
+	ld [$1+1], c
+#endmacro
+#macro m16_write_de
+	ld a, e
+	ld [$1], a
+	ld a, d
+	ld [$1+1], c
+#endmacro
+#macro m16_write_hl
+	ld a, l
+	ld [$1], a
+	ld a, h
+	ld [$1+1], c
+#endmacro
+
 	; 16 bit add
 	; inputs:
 	;		m16_a/m16_b
 	;	returns:
 	;		m16_a: m16_a + m16_b
 m16_add:
+	ld a, [m16_b]
+	ld b, a
+	ld a, [m16_a]
+	
+	; low is stored
+	add a, b
+	ld [m16_a], a
+
+	ld a, [m16_b+1]
+	ld b, a
+	ld a, [m16_a+1]
+
+	; high + carry stored
+	adc a, b
+	ld [m16_a+1], a
+
 	ret
 
 	; 16 bit sub
diff --git a/src/wram.s b/src/wram.s
index 6678bab..b30b9a1 100644
--- a/src/wram.s
+++ b/src/wram.s
@@ -143,6 +143,7 @@ col_y: .adv 1
 col_x: .adv 1
 
 	; 16-bit math temporary registers
+	; store in LE
 m16_a: .adv 2
 m16_b: .adv 2