From 7f1bef07bed73b3c292da92a142b49d7d37a58d5 Mon Sep 17 00:00:00 2001
From: Lukas Krickl <lukas@krickl.dev>
Date: Wed, 18 Feb 2026 05:32:20 +0100
Subject: [PATCH] mapgen: Added pre-computed seeds in save game.

This change makes it easier to store which floor used which seed.
---
 src/defs.s   |  7 +++++++
 src/main.s   |  1 +
 src/mapgen.s | 37 ++++++++++++++++++++++++++++---------
 src/rand.s   | 13 -------------
 src/save.s   | 12 ++++++++++++
 src/sram.s   |  3 ++-
 src/update.s |  1 +
 src/wram.s   |  8 +++-----
 8 files changed, 54 insertions(+), 28 deletions(-)
 create mode 100644 src/save.s

diff --git a/src/defs.s b/src/defs.s
index e152935..a95e004 100644
--- a/src/defs.s
+++ b/src/defs.s
@@ -40,6 +40,8 @@
 #define MAP_TILES (MAP_W * MAP_H)
 #define MAP_SECTION_SIZE 8
 #define MAP_SECTION_PER_ROW (MAP_W / MAP_SECTION_SIZE)
+#define MAPGEN_FLOORS_MAX 24
+
 
 #define RENDER_BUF_W 20
 #define RENDER_BUF_H 14
@@ -332,3 +334,8 @@
 .se 1
 .de M16_CARRY, 1
 .de M16_ZERO, 2
+
+	; save file def
+.se 0
+.de save_mapgen_seeds, 2 * MAPGEN_FLOORS_MAX
+.de save_size, 0
diff --git a/src/main.s b/src/main.s
index 414d820..4ca424d 100644
--- a/src/main.s
+++ b/src/main.s
@@ -72,6 +72,7 @@ main:
 #include "item.s"
 #include "render.s"
 #include "action.s"
+#include "save.s"
 
 #include "tiles.inc"
 #include "text.s"
diff --git a/src/mapgen.s b/src/mapgen.s
index b771602..3aaab42 100644
--- a/src/mapgen.s
+++ b/src/mapgen.s
@@ -1,3 +1,23 @@
+
+	; creates MAPGEN_FLOORS_MAX
+	; seeds for the current file
+mapgen_init_seeds:
+	call mbc1_ram_enable
+	
+	call save_file_select
+
+	; now load 2 * MAPGEN_FLOORS_MAX 
+	; numbers into rng
+	ld b, MAPGEN_FLOORS_MAX * 2
+@loop:
+		call rand
+		ld [hl+], a
+		dec b
+		jr z, @loop REL
+	
+	call mbc1_ram_disable
+	ret
+
 	; generates a map
 	; inputs:
 	; mapgen_: map gen settings
@@ -18,10 +38,15 @@ map_generate:
 	ld [mapgen_game_seed+1], a
 
 	; load the seed
-	ld a, [mapgen_seed]
+	call save_file_select
+	ld d, 0
+	ld a, [mapgen_floor]
+	add a, a ; *2 because the mapgen seed is 2 bytes
+	ld e, a
+	ld a, [hl+]
+	ld [srand], a
+	ld a, [hl]
 	ld [srand], a
-	ld a, [mapgen_seed+1]
-	ld [srand+1], a
 
 	; 2) set up map header
 
@@ -56,12 +81,6 @@ map_generate:
 	
 
 	; cleanup) finally
-	; store current seed
-	ld a, [srand]
-	ld [mapgen_seed], a
-	ld a, [srand+1]
-	ld [mapgen_seed+1], a
-
 	; restore game seed from rng
 	ld [mapgen_game_seed], a
 	ld [srand], a
diff --git a/src/rand.s b/src/rand.s
index e9b057c..73ec2f7 100644
--- a/src/rand.s
+++ b/src/rand.s
@@ -12,13 +12,6 @@ rand_init:
   or a, 1
   ld [srand+1], a
 
-	ld a, [sram_mapgen_srand]
-	or a, 1
-	ld [mapgen_seed], a
-	ld a, [sram_mapgen_srand+1]
-	or a, 1
-	ld [mapgen_seed+1], a
-
   call mbc1_ram_disable
   ret
 
@@ -33,12 +26,6 @@ rand_save_srand:
   ld a, [srand+1]
   ld [sram_srand+1], a
 
-	; save mapgen seed in sram
-	ld a, [mapgen_seed]
-	ld [sram_mapgen_srand], a
-	ld a, [mapgen_seed+1]
-	ld [sram_mapgen_srand], a
-
   call mbc1_ram_disable
   ret
 
diff --git a/src/save.s b/src/save.s
new file mode 100644
index 0000000..e9c075e
--- /dev/null
+++ b/src/save.s
@@ -0,0 +1,12 @@
+
+	; loads the current save file
+	; reutnrs:
+	;		hl: save file
+save_file_select:
+	ld a, [savefile_selected]
+	ld d, a
+	ld a, [savefile_selected+1]
+	ld e, a
+	ld hl, savegame0 + save_mapgen_seeds
+	add hl, de
+	ret
diff --git a/src/sram.s b/src/sram.s
index e6ffe55..32f1657 100644
--- a/src/sram.s
+++ b/src/sram.s
@@ -10,4 +10,5 @@
   ; flag for init of sram
 sram_magic: .adv 1
 sram_srand: .adv 2
-sram_mapgen_srand: .adv 2
+
+savegame0: .adv save_size
diff --git a/src/update.s b/src/update.s
index fa2969b..c521b65 100644
--- a/src/update.s
+++ b/src/update.s
@@ -159,6 +159,7 @@ update_render:
 	ret
 	
 new_game:
+	call mapgen_init_seeds
 	call map_generate
 
 	call player_init
diff --git a/src/wram.s b/src/wram.s
index 376d05a..27ed876 100644
--- a/src/wram.s
+++ b/src/wram.s
@@ -117,8 +117,6 @@ map: .adv 2
 	
 	; map generator settings
 	
-	; the seed used for the current map
-mapgen_seed: .adv 2
 	; ptr to map gen slot flags
 	; this can be used to store previous maps states
 	; to allow the player to return
@@ -135,9 +133,9 @@ mapgen_game_seed: .adv 2
 mapgen_floor: .adv 1
 	
 	
-	; collision related data
-	; y/x positions
-	
+	; selected file offset for indexing sram
+	; LE
+savefile_selected: .adv 2
 	
 	; space for 1 tile id
 	; that represent the current tile
-- 
2.30.2