insstr:

Format:

insstr: Rw, Rx, Ry | string, Rz | position

Insert string Ry, into string Rx at position Rz and load into Rw. If position is greater than the length of Rx, then insstr: will append the string to the end of Rx.

Parameters:

Rw: A register that will contain the modified string.
Rx: A register of the string to modify.
Ry | string: A string register or constant of the string to insert.
Rz | position: A numeric register or constant specifying the insert position in Rx.