overlay: finish Gaspar (mountable turret update)

[conor-sometimes]

Before

Gaspar (level 09) had one pending function.

Function		Bytes
FUN_L09_00304c80	mountable turret update	3492

After

It is exact, so Gaspar is complete. One commit, gated, on current main (#171).

It is the turret the hero mounts: he sits in it, aims with the stick and fires the two barrels in turn. Nothing to port (rac1-decomp has it as asm only, and no other planet has a matched copy); written from an m2c draft. The unit is in OVERLAY_SN_UNITS, so it builds with SN cc1 like the rest of 003033a0.c.

Things worth a look

• D_0013E5BC (also read by clamp_voice_position_to_collision; named sound_probe_ignore) is declared as an array and written [0] = moby: as a plain scalar the compiler assumes it can't alias the moby fields and hoists the loads above the store, where retail keeps the store first.
• Case 0's zero stores: vars->unk40 = 0 has to come last in source; the scheduler first emits the store that frees the vars register (checked with -fsched-verbose).
• The beam blink is an if/else chain with the 4.0f/0.4f block written twice, so the compiler reuses the 4.0 already in $f20; the stick y invert has its own stick_y; D_L09_00161CC0 is f32[2] with the sda attribute so Ps2EeAs reaches it through $gp (commented); the two *= 0.97f lines are swapped and the barrel select is vars->barrel == 0 ? 4 : 3.
• The turret's vars, its beam table D_L09_00180440 and D_L09_00166E00 get file-local struct types (no shared header uses them); moby and hero fields come from the shared headers. No configure.py entries, no compiler flags.

Verification

• make elf ends with PASS: reconstructed boot ELF matches retail
• make overlays ends with PASS: all 2780 overlay functions in C match retail, with their 17232 copies in other places
• make check passes

[github-actions]

Decompilation progress

	C_EXACT	Change	Matched bytes	Functions	C_FUZZY
All code	86.65 %	+0.10 pp	3,072,740 / 3,546,268 B (+3,492 B)	3,934 / 4,233 (+1)	87.98 %
Boot executable	84.73 %	—	298,968 / 352,840 B (—)	1,159 / 1,219 (—)	98.11 %
Game	84.26 %	—	229,892 / 272,844 B (—)	865 / 905 (—)	98.40 %
SDK	86.35 %	—	69,076 / 79,996 B (—)	294 / 314 (—)	97.12 %
Level overlays	86.86 %	+0.11 pp	2,773,772 / 3,193,428 B (+3,492 B)	2,775 / 3,014 (+1)	86.86 %
Shared level code	78.82 %	—	891,052 / 1,130,492 B (—)	1,428 / 1,583 (—)	78.82 %
Per-level code	91.26 %	+0.17 pp	1,882,720 / 2,062,936 B (+3,492 B)	1,347 / 1,431 (+1)	91.26 %

1 newly matched function (3,492 B)

Function	Address	Size	Unit
FUN_L09_00304c80	0x00304c80	3,492 B	level_09/gameplay/vendor/003033a0

_{Compared with main (e934c0a). C_FUZZY uses main's last measurement.}

[decomp-dev]

Report for SCUS_971.99 (e934c0a - 64d5a61)

📈 Matched code: 86.65% (+0.10%, +3492 bytes)
📈 Linked code: 86.65% (+0.10%, +3492 bytes)

✅ 1 new match

Unit	Item	Bytes	Before	After
level_09/gameplay/vendor/003033a0	FUN_L09_00304c80	+3492	0.00%	100.00%