[Feature Request] print information placeholder for g-code

[Mikeyzy]

I'm trying to get PS to work with raise3d's printer. Their firmware uses the following g-code comments to display current layer and print time on printer's screen:
in g-code:
;LAYER:78
;PRINTING_TIME: 2392
;REMAINING_TIME: 50

end of file:
;Print Time: 2442
;Material#1 Used: 2079.2
;Material#2 Used: 0.0
;Material#1 Cost: 0.19
;Material#2 Cost: 0.00

time value is in second, material used in cm

Please make the following placeholder available in G-Code, these are available in file name but not for g-code.
print_time, normal_print_time, silent_print_time, used_filament, extruded_volume, total_cost, total_weight, total_wipe_tower_cost, total_wipe_tower_filament

In addition, can we have current_print_time, current_layer_count, remaining_layer_count variables for g-code placeholder. the time placeholder should be numeric

[bkiziuk]

I should add that having normal_print_time and silent_print_time implemented would allow to use M73 R<remaining_time> command in startup G-code to show estimated printing time right at the start of the print.
I'm using Marlin, and until the actual generated M73 is sent to the printer, when running startup G-code the firmware tries to invent some insane numbers.

[ThomasToka]

Today i learned that those variables are missing like stated here in the issue.

print_time, normal_print_time, silent_print_time, used_filament, extruded_volume, total_cost, total_weight, total_wipe_tower_cost, total_wipe_tower_filament

Would be really cool to have them available in custom g-code.

Thanks!