AHDL Function Prototype (port name and order also apply to Verilog HDL)
The following AHDL function prototype is located in the AHDL Include File (.inc) Definitionaltsource_probe.inc in the <Intel® Quartus® Prime installation directory>\libraries\megafunctions directory.
FUNCTION altsource_probe(
        probe[probe_width-1..0],
        source[source_width-1..0],
        source_clk,
        source_ena
)
WITH(
        enable_metastability,
        instance_id,
        lpm_hint,
        lpm_type,
        probe_width,
        sld_auto_instance_index,
        sld_instance_index,
        source_initial_value,
        source_width
)
RETURNS(
        source[source_width-1..0]
);