crt0.nx

crt0.nx -- sovereign `_start` stub for NishiLang programs. Replaces the libc/crt0 that C programs silently link against. The Linux kernel hands us a stack laid out like: sp ------------------------> argc (i64) sp + 8 --------------------> argv[0] (*u8, program name) sp + 16 -------------------> argv[1] (*u8, first real arg) ... sp + 8 + argc*8 -----------> NULL ... envp[0], ..., NULL, auxv... We translate that into the (argc, argv) signature parse.nx expects for main() -- a0 = argc, a1 = argv -- then call main. On return, exit(a0) via the SYS_exit (93) syscall. This file defines `_start` only as source TEXT because NishiLang doesn't yet have a way to declare symbols at specific file offsets or pin a function's emission order. Drivers emit this text at the head of their assembled output so it lands at the ELF entry point. Usage (see runtime/nxc.nx): emit_start_stub(asm_buf) // ... emit user's functions ... assemble(asm_buf, ...) write_elf(code, code_len, fd)