"SUBR" Subroutine extension

Fingerprint ID:0x53554252

New in version 0.5-rc2.

This fingerprint, from RC/Funge-98, implements a function call to arbitrary Funge code and a return from it. It provides the following commands:

A : —

Sets the absolute mode, so the jump location is independent to IP’s storage offset. This is a default behavior.

C : a₁ ... a_n pos^v n — origpos^v origdelta^v a₁ ... a_n

Calls a subroutine at pos and saves the original position and delta as origpos and origdelta. After the call IP travels towards right. It pops n items from the stack as well, and moves them to the top of the stack. Reflects if n is negative.

J : pos^v —

Jumps to given pos, and make IP travels towards right. It doesn’t store any return information.

O : —

Sets the relative mode, so the jump location is relative to IP’s storage offset.

R : origpos^v origdelta^v a₁ ... a_n n — a₁ ... a_n

Returns from a subroutine and restores the position and delta to origpos and origdelta, respectively. It also pops n items from the stack and moes them to the top of the stack. Reflects if n is negative.