SEFL Syntax

SEFL Syntax

Base language structures

• tag: 'tag_id'; 'L3', 'L2'
• tag_expression: an arithmetic expression encolsed in square brackets using + or - and numbers or tags, parenthesis are not allowed; ['L2' + 100], ['L2' + 'L3' - 15 + 100]
• lvalue
  • Metadata field: "id"; "flag"
  • Tag expression: tag_expression; ['L2'], ['L2' + 15]
• rvalue:
  • Tag expression
  • Metadata field
  • • or - and the above ones, no paranthesis; [L2 + 100] + "sum" - 10 + ['L3']

Instructions

One instruction per line, empty lines are allowed.

Only single line comments are allowed currently, a comment line starts with a #.

• Allocate lvalue[, size], for example: "IPSrc", "L2 + 15, 100" if a tag expression is used, the size is mandatory.
• Assign: lvalue = rvalue
• Constrain:
  • lvalue <- arithmetic_constraint
  • lvalue <- ! arithmetic_constraint
  • lvalue <- arithmetic_constraint | arithmetic_constraint
  • lvalue <- arithmetic_constraint & arithmetic_constraint
  • any permutation of these using proper placing of the parenthesis

• Exists: ? lvalue

• If: if (constrain_instruction) instruction_block else instruction_block
• Create tag: tag(id, tag_expression); tag(L2, 0), tag(Encap, L2 - 200)
• Instruction blocks:
  • sequential instruction block(basic): {instructions}

- fork: `f{instructions}`

- parallel: `p{instructions}`

• Destroy tag: untag(id)
• Deallocate: ! lvalue

• Fail: !
• Forward: -> port_id
• Noop: -