setjmp and longjmp implementation in mmix
Looks like your setjmp takes the jmp_buf parameter as $0 - but how is jmp_buf defined - how much space does it need for example?
Also longjmp takes 2 parameters - the same jmp_buf and an int - I don't see $1 being used for the second input parameter in your longjmp
You can find commandline tools to run MMIX programs at https://mmix.cs.hm.edu/exe to try out your implementation - there's a Windows GUI debugger too - could you show sample MMIX code that calls your setjmp and longjmp?