CREDIT CHECK

CREDIT_CHECK ($C00450)
BIOS routine called to check if there's enough credits for a player.

Input: $10FDB0 (BIOS_CREDIT_DEC) for player 1, and $10FDB1 (BIOS_CREDIT_DEC2) for player 2. Those locations are set to 0 if there aren't enough credits.

Call CREDIT_DOWN after.