awetmore wrote: I'm trying to read the raw machine coordinates from G-Code.
This simple idea should be plainly documented, but is not. It also needs a formal name, which I propound should be "the
instant ordinate" of an axis (calling it "raw" or "machine" is not informative since the G-code machine model is a hairball of confusion). Here is an O-code subroutine gem to do it universally for any machine state and axis:
Code:
( Subroutine: read current g53 location )
( Input: #1 = axis code 0..8 )
( Returns: #31 = location )
( Side effects: clobbers #5161--#5169 by using g28.1 )
( RJK 02/2019 )
o<read_ordinate> sub
( Scaffold: modify this using a subr which push-probe-pops #5161--#5166 )
( to avoid potentially interfering with caller's state )
( Scaffold: does not check axis is a valid code, both in range and )
( installed. )
g28.1 ( Read current g53 coordinates into #5161--#5166 )
#31 = [#[5161+#1]] ( G53 ordinate for axis of interest )
o<read_ordinate> endsub
You can see there are only two lines of code required. This is clumsy and not obvious even to experts, but that's G-code.
Even this subroutine is not quite pure; it ought to push and pop the g28.1 conditions, such as with subroutine local variables, to guarantee no global side effects. Such purity requires it be done in a subroutine, which is itself an insoluble impurity; there's
no proper way to do this in G-code that is both "flat" and not dependent on a language extension (such as a subroutine). This model deficiency explains the embarrassment of it not being documented. The ugliest measles always get documented last.
