# RX4E4Z - Casper's Scare School: Spooky Sports Day

[OnFrame]
# Work around a dcache issue by preventing the game from doing something pointless.
#
# The game's DVD read function writes 0x87654321 to the entire read buffer and 0x12345678 to the
# last 4 bytes. It then calls DVDReadAsync() and without waiting for the read to complete at all,
# it checks if the last 4 bytes are still 0x12345678. If they are, then the game fails.
#
# The check always passes on console because DVDReadAsync() -> issueCommand() calls
# DCInvalidateRange() (dcbi) on the read buffer.
#
# Dolphin cannot emulate this without an extremely significant performance hit.
#
# .text:800D2E64 lis       r7, game_dvd_read_callback@ha
# .text:800D2E68 stw       r0, 0(r17) # write 0x12345678 to the end of the buffer
# .text:800D2E6C mr        r5, read_length # length
# .text:800D2E70 mr        r6, read_offset # offset
# .text:800D2E74 addi      r3, this, file.file_info # file_info
# .text:800D2E78 subi      r4, r4, dvd_read_buf@l # addr
# .text:800D2E7C addi      r7, r7, game_dvd_read_callback@l # callback
# .text:800D2E80 li        r8, 2         # unknown
# .text:800D2E84 bl        DVDReadAsync
#
$Fix file reads (dcache bypass)
0x800d2e68:dword:0x60000000
[OnFrame_Enabled]
$Fix file reads (dcache bypass)

[Patches_RetroAchievements_Verified]
$Fix file reads (dcache bypass)
