Routines
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41029: Add Points To Score
Used by the routines at Destroy_Creature and Handle_Collectable.
Adds to the score (see Score) and prints the new score at the top of the screen.
The amount is a pair of BCD bytes: B holds the hundreds and C the units. One is taken off C before it is added, so when C is not zero the score goes up by B hundreds plus C minus one. When C is 0 it goes up by B hundreds plus 99.
Before After AddPointsToScore
add-points-before add-points-after
Input
B Hundreds to add, as two BCD digits
C Units to add, as two BCD digits (see above)
AddPointsToScore 41029 LD HL,36597 Point at the low byte of the score (Score_Low_Byte).
41032 XOR A Clear A (which also clears the carry flag).
41033 LD A,C Fetch the low byte of the amount.
41034 DEC A Subtract one, in BCD.
41035 DAA
41036 ADD A,(HL) Add the low byte of the score and adjust the result to a BCD value.
41037 DAA
41038 LD (HL),A Store the new low byte of the score.
41039 DEC HL Move on to the middle byte of the score.
41040 LD A,(HL) Fetch the middle byte of the score.
41041 ADC A,B Add the high byte of the amount and the carry.
41042 DAA Adjust the result to a BCD value.
41043 LD (HL),A Store the new middle byte of the score.
41044 DEC HL Move on to the high byte of the score.
41045 LD A,(HL) Fetch the high byte of the score.
41046 ADC A,0 Add the carry.
41048 DAA Adjust the result to a BCD value.
41049 LD (HL),A Store the new high byte of the score.
41050 LD HL,48 Set the x position to 48 and the y position to 0 (48).
41053 LD DE,36595 Point at the score (Score).
41056 LD B,3 Set the number of digits to print to 3.
41058 CALL ScreenAddress Convert the position into a screen address.
41061 JP Print_Status_Panel_Digits Jump to Print_Status_Panel_Digits to print the digits.
View the equivalent code in;
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