6-digit* HexToDec subroutine to write a player's score into status bar.
Call with Y = #$00, X as the position to write to on the status bar (standard is #$14), and $00-$03 as the score to write (in hexadecimal). Note that this routine does not remove leading 0s; that is handled at $008EDE and $008F0C.
Works like this: count how many subtractions by 10n (with n=5) without the difference going into the negatives; that number of subtractions is the digit for the 10ns place. Then repeat but with 10n-1. This is the "left-to-right" version of base conversion using repeated subtraction to emulate the 32-bit division by 10n.
*SMW displays the score as 7 digits, but the score is actually a 6-digit (decimal) number stored internally, the 7th digit "0" is a static tile not part of this number.