add B2 patch support on PSO Plus

2024-06-22 21:38:24 -07:00
parent 998664d2fb
commit 862b3d27da
21 changed files with 465 additions and 96 deletions
@@ -0,0 +1,59 @@
+.version GC_V3
+.quest_num 88500
+.language 1
+.episode Episode1
+.name "GC v1.2 USA patch enabler"
+.short_desc ""
+.long_desc ""
+
+start:
+  // Create quest opcode handlers for F9FE to call flush_code and F9FF to call
+  // the copied code. Fortunately, quest_call_l leaved the byteswapped value of
+  // the opcode argument in r4, so as long as the address ends with 00, it will
+  // be valid as the size argument to flush_code. We'll end up flushing many
+  // more bytes than needed, but this isn't a problem.
+  leti               r3, 0x80004000  // dest addr
+  write4             0x804C81C8, 0x801F2A14  // quest_call_l
+  write4             0x804C81CC, 0x8000C274  // flush_code
+  write4             0x804C81D0, r3  // written code ptr
+
+  read4              r0, 0x805D5E70  // quest_script_base
+  leto               r4, code
+  read4              r4, r4
+  add                r4, r0  // r4 = address of code label
+  leto               r5, code_end
+  read4              r5, r5
+  add                r5, r0  // r5 = address of code_end label
+
+  // Copy all data from [code, code_end) to 80004000
+copy_byte:
+  jmp_eq             r4, r5, copy_done
+  read1              r0, r4
+  write1             r3, r0
+  addi               r3, 1
+  addi               r4, 1
+  jmp                copy_byte
+
+copy_done:
+  // Call flush_code(0x80004000, 0x00400080) to commit it to memory
+  .data              F9FE00400080
+  // Call the copied native code
+  .data              F9FF
+
+  // This script runs on the first frame during the quest loading procedure,
+  // but this procedure is started from the lobby overview, not from a game!
+  // To make the result of loading a quest sane, we need to set some extra
+  // state that will take effect when loading is done.
+  ba_initial_floor   17  // Make player spawn in lobby (for one frame)
+  write2             0x805D5CE8, 1  // Leave "game" immediately (sends 98)
+
+  // Clean up quest handler table
+  write4             0x804C81C8, 0
+  write4             0x804C81CC, 0
+  write4             0x804C81D0, 0
+
+  ret
+
+code:
+  .include_native    q88500-gc.s
+code_end: