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J. Nick Koston
9a8d17e3c8
On RP2040, the core0 stack lives in a 4KB SCRATCH_Y RAM bank. The Noise protocol handshake calls into curve25519 scalar multiplication which needs ~2KB+ of stack. When all handshake state branches lived in a single function, the compiler allocated stack space for all branches simultaneously (SERVER_HELLO msg[46]+mac[13], HANDSHAKE buffer[65], NoiseBuffer, etc.), leaving insufficient headroom for the crypto path. Split state_action_() into per-state methods so each state's locals occupy separate stack frames. The crypto path (WRITE_MESSAGE) now only carries its own 85 bytes of locals instead of ~200+ bytes from all branches combined.
