WebAssembly

One of the supported actors in Manifest is WebAssembly (WASM). To gain support as an actor in Kolmonet, WASM must support the special interface (listed below). The implemented sequence of calls is:

• For each argument:
  • Reserve memory for the argument name (_set_arg_name)
  • Set to reserved memory name of the argument
  • Get argument’s index (_get_arg_index)
  • Reserve memory for the argument’s value (_set_arg)
  • Set to reserved memory argument’s value
• Execute WASM algorithm (_exec)
• Get result’s pointer and size (_get_result, _get_result_size)
• If any errors occur get error’s pointer and size to get an error message(_get_last_error, _get_last_error_size)

WASM interface (Rust):

_set_arg_name(arg_handle: u8, size: usize) -> *mut c_void
_get_arg_index(arg_handle: u8) -> u8
_set_arg(arg_index: u8, size: usize) -> *mut c_void
_get_result() -> *mut c_void 
_get_result_size() -> usize 
_get_last_error() -> *mut c_void 
_get_last_error_size() -> usize 
_exec() -> bool 

WASM interface ©:

int* _set_arg_name(uint8_t arg_handle, int size)
uint8_t _get_arg_index(uint8_t arg_handle)
int* _set_arg(uint8_t arg_index, int size)
int* _get_result()
int _get_result_size()
int* _get_last_error()
int _get_last_error_size()
int _exec()

_set_arg_name

This method reserve memory inside WASM for receiving the parameter’s name. Parameter identified by its handle. Later, parameter handle will use for getting parameter index by calling _get_arg_index. The goal of call sequence _set_arg_name -> _get_arg_index is to get parameter index by parameter’s name. It allows naming parameters in Manifest in a human readable form.

Parameters: - arg_handle - parameter’s handle - size - size in bytes for name of parameter

Return value: - Pointer to memory inside WASM (null if error)

_get_arg_index

This method allows getting parameter index by parameter’s handle. Parameter index will be used later for call _set_arg.

Parameters: - arg_handle - parameter’s handle

Return value: - Argument index (0 if error)

_set_arg

This method reserve memory inside WASM for receiving the parameter’s value.

Parameters: - arg_index - parameter’s index - size - size in bytes for value of parameter

Return value: - Pointer to memory inside WASM (null if error)

_get_result

This method return pointer to memory containing the result of WASM execution.

Return value: - Pointer to memory inside WASM (null if error)

_get_result_size

This method return size of memory containing the result of WASM execution.

Return value: - Size of memory inside WASM (0 if execution error occurs or has no executed yet)

_get_last_error

This method return pointer to memory containing error message of last WASM unsuccessful call.

Return value: - Pointer to memory inside WASM (null if error)

_get_last_error_size

This method return size of memory containing error message of last WASM unsuccessful call.

Return value: - Size of memory inside WASM (0 if no error was detected)

_exec

This method make execution of WASM algorithm. All arguments of the algorithm must be initialized before calling.

Return value: - Result of execution (true if succeeded, false if execution failed)