Routines
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28295: Adjust Sam's cash supply and print the new amount
Used by the routines at 31594, 31642 and 64338. Returns with the zero flag set if Sam has run out of money.
Input
A N/10 (N=number of bucks to subtract)
28295 LD E,A A=N
28296 ADD A,A
28297 ADD A,A
28298 ADD A,E
28299 ADD A,A
This entry point is used by the routine at 30458 with A=2.
28300 LD D,255 Prepare DE for subtraction
28302 NEG A=-N
28304 JR 28308
This entry point is used by the routines at 25039, 28760 and 30211 with A holding the number of bucks to add to Sam's cash supply.
28306 LD D,0 Prepare DE for addition
28308 LD E,A Now DE=number of bucks to add (may be negative)
This entry point is used by the routine at 28337 with DE=65535 (-1).
28309 LD HL,(32670) Collect the current number of bucks from 32670
28312 ADD HL,DE Adjust the number
28313 INC H Is the result negative?
28314 JR NZ,28319 Jump if not
28316 LD HL,256 Set HL up so that the next instruction reduces it to 0
28319 DEC H Restore the value of HL (if it was non-negative), or set it to 0 (if it was negative)
28320 LD A,H Set the zero flag if the number of bucks is now 0
28321 OR L
28322 PUSH AF Save the zero flag temporarily
28323 LD (32670),HL Store the new amount at 32670
28326 LD DE,20728 DE=display file address
28329 CALL 28186 Print the number of bucks
28332 POP AF Restore the zero flag
28333 RET
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