Splice - a DSL for Software-Defined Satellite Applications

Current (OPS-SAT version of Splice) minimal language specifications

variables/constants:

• variable or constant names: alphanumeric, starts with letter a-zA-Z[0-9a-zA-Z]*
• only simple, non-compound typed variables are possible i.e
  • var variable1:i32 or var variable2:f32 are acceptable declarations, anything else isn’t

numeric literals:

• positive and negative 32-bit integers, i.e -1, 0, 40001
• single-precision floating points, just like in C, i.e. 1E-15, or -9.0E4;

types:

• two types supported explicitely: i32 (signed integers) and f32 (single precision floating point)
• boolean type supported implicitely for “prerequisites” section (preq)

expressions and statements:

• basic arithmetic, transcendental and trigonometric operations and assignment operator supported
• Refer to Splice whitepaper for full list of operations supported by VM assembly
• only boolean expressions allowed in preq section
• only assignment/math expressions allowed in exec section

keywords (task list file only):

• group, task, data, freq, preq, exec, var, f32, i32, const, return

keywords (instrument definition file only):

• inst, queue, size, type, accs, shed, var, prop

program structure (as described in whitepaper):

• multiple groups and tasks (up to 16 groups with up to 16 taks in each group)
• group can included multiple tasks
• each group and each task has a name
• tasks in the same group have read-only visibility of each other data
• task structure:
  • data section
  • frequency section (how often to repeat the task: “once”, at fixed interval or “always” - as fast as scheduler allows)
  • prerequisites section (what has to be true for task to run)
  • executive section (the actual task code)

OPS-SAT instrument specifications

• Camera, GPS and ADCS instruments are available at the moment - instrument definition file TBD

Compilation process imagined:

• Instrument definition files (.spli extension) are provided from the satellite operations team
• Group/task list in a source file (.spl extension) are provided from software developers
• Each task is compiled into a single assembly file (.splc)
• Linker can produce a semi-binary executable file compatible with VM OPS-SAT from one or many assembly files (.splx)
• Source: (.spl+.spli) -> assembly representation (.splc) -> executable format (.splx)
• For future satellite missions both assembly and executable formats can and should change, but high-level syntax should’t
• Each satellite may have its own instrument definition file (.spli), slightly or significantly different from each other