Every stick read passes through here
This is real input code: the function the game runs on every raw joystick axis, every frame. Sticks drift, so tiny values must read as zero; old hardware ranges vary, so big values must clamp. The C is a ladder of small ifs on a narrow signed value — which makes the assembly a study in how this compiler handles narrow signed math.
An s8 in a register is just an s32 that promises to stay small. After arithmetic the compiler must re-narrow it, and on this CPU that's the sll 24 / sra 24 pair from tier 2. Watch throttleUp nudge and clamp a throttle:
0: sw a0, 0(sp) # narrow arg homed — the -g3 ritual
4: sll t6, a0, 24
8: sra a0, t6, 24 # re-extend the incoming s8
c: addiu a0, a0, 5 # t + 5
10: sll t8, a0, 24
14: sra a0, t8, 24 # the sum is an int — squeeze it back to s8
18: slti at, a0, 91 # t < 91, i.e. t <= 90
1c: bnezl at, 0x2c # in range → skip the clamp
20: or v0, a0, zero # (slot) result = t
24: addiu a0, zero, 90 # clamp value
28: or v0, a0, zero
2c: jr ra
30: nop
Two reading rules to carry in:
slti immediates are off by one from the C. slti at, a0, 91 paired with "skip if true" is <= 90; on the negative side, slti at, a0, -7 being false means > -8. When you see a strange immediate, add or subtract one and ask which comparison the branch sense implies.- The
sll/sra pairs are free. They come from the variable being s8, not from anything you write. Declare the right type and they appear.
The target opens with something extra: a lbu from a global — the engine's "ignore the stick" flag, tested before anything else. The global's name is in the reloc, and the context declares it. After that it's the ladder: a dead zone that returns zero, then a positive path and a negative path, each with a shift-toward-zero and a clamp. Follow each branch to its jr ra and note what's in v0 when it gets there.
Your task
Write func_801cc238 to reproduce the target assembly.