From d0f73990e236c5614e2d0303b8b227846aaecd71 Mon Sep 17 00:00:00 2001
From: Lukas Krickl <lukas@krickl.dev>
Date: Wed, 26 Nov 2025 05:51:59 +0100
Subject: [PATCH] map: vram origin is now configurable

---
 src/map.s  | 19 +++++++++++++++++--
 src/mem.s  |  3 +++
 src/wram.s |  3 +++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/src/map.s b/src/map.s
index a457a80..ce2eb49 100644
--- a/src/map.s
+++ b/src/map.s
@@ -1,4 +1,14 @@
 #define SCRN0_END 0x9BF3
+	
+	; inits map globals
+	; such as map_vram_tl
+map_globals_init:
+	ld hl, SCRN0
+	ld a, h
+	ld [map_vram_tl], a
+	ld a, l
+	ld [map_vram_tl+1], a
+	ret
 
 	; loads a map 
 	; including the required tileset
@@ -230,8 +240,13 @@ map_draw_tile_prep:
 	; load tile into a
 	ld a, [hl] ; a = tile
 	push af ; save tile gfx
-
-	ld hl, SCRN0
+	
+	; TODO: this needs to wrap around
+	; if hl goes oob in y-loop
+	ld a, [map_vram_tl]
+	ld h, a
+	ld a, [map_vram_tl+1]
+	ld l, a
 	ld de, ((MAP_W * 2) + 12) * 2 ; * 4 because tiles are 8x8 
 	
 	; skip y loop if b is 0
diff --git a/src/mem.s b/src/mem.s
index 60da28e..00662ef 100644
--- a/src/mem.s
+++ b/src/mem.s
@@ -4,6 +4,8 @@ mem_init:
   ld hl, WRAM
   ld bc, WRAMLEN
   call memset
+
+	call map_globals_init
   
   ; set up shadow IE
   ld a, IVBLANK | ILCD
@@ -29,6 +31,7 @@ mem_init:
 	ld hl, new_game 
 	call game_set_state
 
+
   ret
 
 ; copies memory from one location to another 
diff --git a/src/wram.s b/src/wram.s
index 4dcc26c..026b41d 100644
--- a/src/wram.s
+++ b/src/wram.s
@@ -84,6 +84,9 @@ tmp_x: .adv 1
 	
 	; current map ptr
 map: .adv 2
+	; ptr to top left corner of SCRN
+	; where the map should be drawn
+map_vram_tl: .adv 2
 	
 	; ptr to current tile to be updated
 tiles: .adv t_size * MAP_TILES
-- 
2.30.2