From af56b6d2c69e81ff19acd74e7558796544edafdf Mon Sep 17 00:00:00 2001
From: Martin Michelsen <fuzziqersoftware+g@gmail.com>
Date: Tue, 27 Jun 2023 00:26:47 -0700
Subject: [PATCH] describe how extension data works

---
 src/Player.cc | 10 +++++++---
 src/Player.hh | 31 +++++++++++++++++++++++++++++--
 2 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/src/Player.cc b/src/Player.cc
index 6349e0d7..bf3139e5 100644
--- a/src/Player.cc
+++ b/src/Player.cc
@@ -79,7 +79,7 @@ PlayerDispDataBB PlayerDispDataDCPCV3::to_bb() const {
   bb.visual.name = "         0";
   bb.name = add_language_marker(this->visual.name, 'J');
   bb.config = this->config;
-  bb.technique_levels = this->technique_levels;
+  bb.technique_levels = this->v1_technique_levels;
   return bb;
 }
 
@@ -93,7 +93,7 @@ PlayerDispDataDCPCV3 PlayerDispDataBB::to_dcpcv3() const {
   ret.visual = this->visual;
   ret.visual.name = remove_language_marker(this->name);
   ret.config = this->config;
-  ret.technique_levels = this->technique_levels;
+  ret.v1_technique_levels = this->technique_levels;
   return ret;
 }
 
@@ -496,11 +496,15 @@ PlayerInventoryItem::PlayerInventoryItem() {
 
 PlayerInventoryItem::PlayerInventoryItem(const PlayerBankItem& src)
     : present(1),
+      extension_data1(0),
+      extension_data2(0),
       flags(0),
       data(src.data) {}
 
 void PlayerInventoryItem::clear() {
-  this->present = 0x00000000;
+  this->present = 0x0000;
+  this->extension_data1 = 0x00;
+  this->extension_data2 = 0x00;
   this->flags = 0x00000000;
   this->data.clear();
 }
diff --git a/src/Player.hh b/src/Player.hh
index 0b18816c..12ea1c2e 100644
--- a/src/Player.hh
+++ b/src/Player.hh
@@ -17,8 +17,35 @@
 
 struct PlayerBankItem;
 
+// PSO V2 stored some extra data in the character structs in a format that I'm
+// sure Sega thought was very clever for backward compatibility, but for us is
+// just plain annoying. Specifically, they used the third and fourth bytes of
+// the InventoryItem struct to store some things not present in V1. The game
+// stores arrays of bytes striped across these structures. In newserv, we call
+// those fields extension_data. They contain:
+//   items[0].extension_data1 through items[19].extension_data1:
+//       Extended technique levels. The values in the v1_technique_levels array
+//       only go up to 14 (tech level 15); if the player has a technique above
+//       level 15, the corresponding extension_data1 field holds the remaining
+//       levels (so a level 20 tech would have 14 in v1_technique_levels and 5
+//       in the corresponding item's extension_data1 field).
+//   items[0].extension_data2 through items[3].extension_data2:
+//       The value known as unknown_a1 in the PSOGCCharacterFile::Character
+//       struct. See SaveFileFormats.hh.
+//   items[4].extension_data2 through items[7].extension_data2:
+//       The timestamp when the character was last saved, in seconds since
+//       January 1, 2000. Stored little-endian, so items[4] contains the LSB.
+//   items[8].extension_data2 through items[12].extension_data2:
+//       Number of power materials, mind materials, evade materials, def
+//       materials, and luck materials (respectively) used by the player.
+//   items[13].extension_data2 through items[15].extension_data2:
+//       Unknown. These are not an array, but do appear to be related.
+
 struct PlayerInventoryItem { // 0x1C bytes
-  le_uint32_t present;
+  le_uint16_t present;
+  // See note above about these fields
+  uint8_t extension_data1;
+  uint8_t extension_data2;
   le_uint32_t flags; // 8 = equipped
   ItemData data;
 
@@ -125,7 +152,7 @@ struct PlayerDispDataDCPCV3 {
   /* 00 */ PlayerStats stats;
   /* 24 */ PlayerVisualConfig visual;
   /* 74 */ parray<uint8_t, 0x48> config;
-  /* BC */ parray<uint8_t, 0x14> technique_levels;
+  /* BC */ parray<uint8_t, 0x14> v1_technique_levels;
   /* D0 */
 
   // Note: This struct has a default constructor because it's used in a command