52275ddd53
Continuing Q6's last item: the condition on each edge. sub_821C6458's third argument is an EVENT CODE, and state 4 -- reached straight after the main menu is installed, so the input-waiting state -- dispatches on it through a second jump table at 0x821c6b7c, 26 cases. Six are handled and twenty fall through changing nothing: event 0 -> state 0 (TITLE_SCREEN, back to the title) events 3, 5, 8, 25 -> state 8 (LOADING) event 10 -> state 5 So the edges I listed last iteration as "4 -> 0, 5, 8x4" are each now attributed to a specific event, and the input state's graph is complete. One thing I deliberately did NOT promote. The main menu has five items, B returns to the title, and this table has one event to the title, four to LOADING and one elsewhere. That is a tempting fit -- B plus four items that load an external archive plus EXTRAS staying inside GP_TITLE -- and it matches everything measured. It is also a count-match and nothing more: the events are unnamed, nothing shows event 3 is a particular menu row, and state 5 installs no named screen so the EXTRAS half has no support at all. Written down as an observation with that said plainly, because the same shape of reasoning already cost me DIFFICULTY and EXTRA_MENU two iterations ago. Still open: what the event numbers mean, the conditions on edges out of the other states, and what states 1/3/5/6/7/9 do.
75 lines
2.6 KiB
Plaintext
75 lines
2.6 KiB
Plaintext
GamePart_Title's screen state machine -- sub_821C6458, decoded statically.
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DISPATCH
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821c6474 lwz r11, 136(r30) ; state = this+0x88
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821c6478 cmplwi cr6, r11, 0x9 ; 10 states, 0..9
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821c647c bgt cr6, 0x821C75B8 ; out of range -> default
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821c6480 lis r12, 0x821C
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821c6484 addi r12, r12, 25752 ; jump table at 0x821C6498
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821c6488 slwi r0, r11, 2
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821c648c lwzx r0, r12, r0
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821c6490 mtctr r0
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821c6494 bctr
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NOTE: a disassembler decodes 0x821C6498..0x821C64BC as `lwz r16, N(r28)`
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instructions. They are the jump TABLE's ten words, not code.
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STATES
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case 0 -> 0x821c64c0 installs "TITLE_SCREEN"
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case 1 -> 0x821c65d0
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case 2 -> 0x821c66e4 installs "TITLE_MENU"
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case 3 -> 0x821c6b18
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case 4 -> 0x821c6b5c nested switch, table at 0x821c6b7c (live: 0,3,5,8)
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case 5 -> 0x821c6fd4
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case 6 -> 0x821c7028
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case 7 -> 0x821c72dc
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case 8 -> 0x821c733c installs "LOADING"
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case 9 -> 0x821c7558
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TRANSITIONS -- every `li rX,N ; stw rX,136(r30)` in the function
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from to at
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0 1 0x821c6598
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0 2 0x821c65c8
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1 2 0x821c66a4
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1 2 0x821c66dc
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2 4 0x821c6afc
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3 4 0x821c6b54
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4 0 0x821c6e00
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4 5 0x821c6e70
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4 8 0x821c6ed0
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4 8 0x821c6f20
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4 8 0x821c6f7c
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4 8 0x821c6fcc
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5 6 0x821c7020
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6 7 0x821c725c
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6 9 0x821c72a8
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6 2 0x821c72d4
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7 9 0x821c7334
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8 2 0x821c7548
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(state 9 stores nothing -- terminal within this function)
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THE CONDITION ON STATE 4's EDGES -- decoded
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sub_821C6458(this, ?, r5) takes an EVENT CODE in its third argument.
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State 4 -- the input-waiting state -- dispatches on it:
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821c6b5c cmplwi cr6, r27, 0x19 ; 26 events, 0..25
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821c6b60 bgt cr6, <default>
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821c6b68 addi r12, r12, 27516 ; table at 0x821c6b7c
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821c6b78 bctr
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Only 6 of the 26 are handled; the other 20 fall through with no state change.
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event 0 -> block 0x821c6be4 -> state 0 (TITLE_SCREEN -- back to the title)
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event 3 -> block 0x821c6e78 -> state 8 (LOADING)
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event 5 -> block 0x821c6f84 -> state 8 (LOADING)
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event 8 -> block 0x821c6f34 -> state 8 (LOADING)
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event 10 -> block 0x821c6e28 -> state 5
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event 25 -> block 0x821c6ed8 -> state 8 (LOADING)
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WHAT IS NOT DECODED
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* what the event NUMBERS mean -- button id, menu-item id or message id;
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* the conditions on edges out of states other than 4;
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* what states 1, 3, 5, 6, 7 and 9 do (they install no named screen);
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* state 3 is never a destination here, so something outside this function
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sets it.
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