Call Inner Subroutine (WORLD.BIN)

#   ROUTINE: CALL INNER SUBROUTINE (ON MAIN THREAD) (WORLD.BIN)
#       This routine acts as a wrapper for a call to another routine, and forces the routine to run on the main thread (thread 0).
#       This routine is the WORLD.BIN analog of Call Inner Subroutine in BATTLE.BIN.
#
#       Parameters:
#           Parameters for inner subroutine: r4 - r7 with additional parameters on the stack, as usual
#           *0x801cd78c = [Address of subroutine to call]
#
#       Returns:
#           r2 = [Result of inner subroutine]

80100384: 3c018010 lui r1,0x8010
80100388: 00200821 addu r1,r1,r0
8010038c: ac3f042c sw r31,0x042c(r1)                #   Save return address to 0x8010042c
80100390: 3c01801d lui r1,0x801d
80100394: 00200821 addu r1,r1,r0
80100398: 8c28d170 lw r8,-0x2e90(r1)                #   threadID (*0x801cd170)
8010039c: 00000000 nop
801003a0: 11000015 beq r8,r0,0x801003f8             #   if (threadID != 0)
801003a4: 00000000 nop                              #   {
801003a8: 3c018015 lui r1,0x8015
801003ac: 00200821 addu r1,r1,r0
801003b0: 8c28327c lw r8,0x327c(r1)                 #       threads[0] (*0x8015327c)
801003b4: 00000000 nop
801003b8: 8d08003c lw r8,0x003c(r8)                 #       threads[0].StackPointer
801003bc: 00000000 nop
801003c0: 2108fff0 addi r8,r8,-0x0010               #       Save stack pointer
801003c4: ad1d0004 sw r29,0x0004(r8)
801003c8: ad1f0008 sw r31,0x0008(r8)                
801003cc: 0100e821 addu r29,r8,r0                   #       $sp = threads[0].StackPointer
801003d0: 3c01801d lui r1,0x801d
801003d4: 00200821 addu r1,r1,r0
801003d8: 8c28d78c lw r8,-0x2874(r1)                #       *0x801cd78c
801003dc: 00000000 nop
801003e0: 0100f809 jalr r8,r31                      #       Call subroutine at *0x801cd78c
801003e4: 00000000 nop
801003e8: 8fbf0008 lw r31,0x0008(r29)
801003ec: 8fbd0004 lw r29,0x0004(r29)               #       Load stack pointer back
801003f0: 03e00008 jr r31
801003f4: 00000000 nop                              #   } else {
801003f8: 3c01801d lui r1,0x801d
801003fc: 00200821 addu r1,r1,r0
80100400: 8c28d78c lw r8,-0x2874(r1)                #       *0x801cd78c
80100404: 00000000 nop
80100408: 0100f809 jalr r8,r31                      #       Call subroutine at *0x801cd78c
8010040c: 00000000 nop
80100410: 3c018010 lui r1,0x8010
80100414: 00200821 addu r1,r1,r0
80100418: 8c3f042c lw r31,0x042c(r1)                #       Load return address from 0x8010042c
8010041c: 00000000 nop
80100420: 03e00008 jr r31
80100424: 00000000 nop                              #   }