[wip] Use NKEY actor for freestanding items instead of RUPY

.pre-commit-config.yaml

@@ -77,3 +77,15 @@ repos:
     rev: v14.0.6
     hooks:
     - id: clang-format
+
+ci:
+  autofix_commit_msg: |
+      [pre-commit.ci] auto fixes from pre-commit.com hooks
+
+      for more information, see https://pre-commit.ci
+  autofix_prs: true
+  autoupdate_branch: ''
+  autoupdate_commit_msg: '[pre-commit.ci] pre-commit autoupdate'
+  autoupdate_schedule: weekly
+  skip: []
+  submodules: false

base/src/get_npc_model_offset.c

@@ -0,0 +1,16 @@
+#include <stdint.h>
+
+uint32_t get_npc_model_offset(uint32_t item_id) {
+  // These values are offsets that are used to calculate the char* that contains
+  // the name of the .bin
+  //  file (see: Npc/ directory in the rom) of the NPC being spawned. The exact
+  //  way it is used is:
+  // char *npc = 20ddf40 + (<return_value> * 0xC)
+  switch (item_id) {
+  case 0x1: // key
+    return 0xC;
+  case 0x3: // oshus sword
+    return 0xE3;
+  }
+  // TODO: calculate values for rest of items
+}

base/src/main.asm

@@ -14,9 +14,46 @@
             .arm
             .importobj "src/faster_boat.o"
             .importobj "src/fixed_random_treasure_in_shop.o"
-            .importobj "src/progressive_sword_check.o"
+            .importobj "src/progressive_sword_check.o
+            .importobj "src/get_npc_model_offset.o"
             .importobj "src/rando_settings.o"
             .include "_island_shop_files.asm"
+
+            .align
+            @spawn_custom_item_with_nkey:
+                ldr r0, =0x21608a8
+                ldr r0, [r0]
+                ldr r0, [r0]
+                add r0, r0, 0x2a0
+
+                ; Dynamically determine pointer to string of
+                ; nsbmd/nsbtx model.
+                push r0, r1, r4, r5
+                mov r5, r0
+                ldr r0, [r4, 0x20]
+                bl get_npc_model_offset
+                str r0, [r5, 0x10]
+                pop r0, r1, r4, r5
+                mov r1, 0x0
+                str r1, [r0]
+                bl 0x20c4528
+
+                mov r1, r0
+                add r0, r4, 0x158
+                ldr r2, [r0]
+                ldr r2, [r2, 0xc]
+                blx r2
+
+                ; Note, this instruction differs from the original code.
+                ; Instead of a `mov r0, 0x1` (i.e. always setting the item id
+                ; to 0x1 for a small key), we're loading the item id dynamically
+                ; from the value given in the ITGE actor in the ZMB. See
+                ; `spawn_custom_freestanding_item.c` for more info.
+                ldr r0, [r4, 0x20]
+
+                str r0, [r4, 0x1b4]
+                b 0x2160798
+
         .endarea
 
     .org 0x54894 + 0x2004000
@@ -220,6 +257,15 @@
 .close
 
 
+.open "../overlay/overlay_0035.bin", 0x0215b400
+    .arm
+    .org 0x216072c
+        .area 0x24, 0x00
+            beq @spawn_custom_item_with_nkey
+        .endarea
+.close
+
+
 .open "../overlay/overlay_0037.bin", 0x0215b400
     .arm
     .org 0x216278c

base/src/spawn_custom_freestanding_item.c

@@ -2,6 +2,16 @@
 
 #define RUPY 0x52555059
 
+static uint16_t get_item_id() {
+  uint16_t *item_id_address;
+  // Pull the base address of the NPCA entry's item_id off of the stack.
+  // This value is set in the NPCA section of the
+  // ZMB file in byte 0xC of an ITGE actor.
+  asm volatile("ldr %0, [sp, #0x4]" : "=r"(item_id_address) :);
+  // return the item id
+  return item_id_address[0x10];
+}
+
 /**
  * @param param_1 - original function arg, don't modify
  * @param npc_type - 4 character string representing NPC type.
@@ -14,19 +24,8 @@ uint16_t spawn_custom_freestanding_item(void *param_1, uint32_t npc_type,
   uint16_t (*spawn_npc)(void *, uint32_t, void *, uint16_t *) =
       (void *)0x20C3FE8;
 
-  uint16_t *item_id_address;
-  // pull the base address of the NPCA entry's item_id off of the stack
-  asm volatile("ldr %0, [sp, #0x4]" : "=r"(item_id_address) :);
-
-  // get the item id
-  uint16_t item_id = item_id_address[0x10];
+  uint16_t item_id = get_item_id();
 
-  // if item_id is 0x1, continue as the vanilla game does.
-  if (item_id == 0x1) {
-    return (*spawn_npc)(param_1, npc_type, param_3, param_4);
-  }
-  // Otherwise, set rupy_type to the item_id and spawn a RUPY NPC:
-  // (see `extend_RUPY_npc.c` to see how this value is used)
   *param_4 = item_id;
-  return (*spawn_npc)(param_1, RUPY, param_3, param_4);
+  return (*spawn_npc)(param_1, npc_type, param_3, param_4);
 }