Subroutine which uploads the stripe image pointed by $12 to VRAM. The pointer is loaded from the table at $0084D0, and then the routine at $00871E is called. Afterwards, if $12 is #$00, the stripe image length at $7F837B is set to 0 and the terminator $FF is written to the beginning of $7F837D. In any case, $12 is reset to 0 before returning.
To call this routine from outside bank 0 you can JSL to the wrapper at $0084C8. This should only be done during a blank period (usually NMI).