river-raid: Routine at 9122

9122: Update and print score for current player.

Increments a score digit and propagates carry if needed. The digit offset is calculated as (6 - type), where offset 0 is the leftmost (100,000s) and offset 5 is the rightmost (1s). When carry propagates to type=4 (offset 2, the 1,000s column), add_life is called to award a bonus life. This means bonus lives are awarded every 10,000 points.

Input
A	Update type: determines digit offset (1=1s, 2=10s, 3=100s, 4=1000s+bonus life, 5=10000s, 6=100000s)

update_score

9122

PUSH AF

Save A, open upper screen channel via ROM CHAN_OPEN, restore A.

9123

LD A,$01

9125

CALL $1601

9128

POP AF

9129

CP $04

If update type is 4, award bonus life via add_life.

912B

CALL Z,add_life

912E

LD B,A

Calculate digit offset: C = 6 - update_type.

912F

LD A,$06

9131

SUB B

9132

LD C,A

9133

LD A,($923D)

Load current player number.

9136

CP $02

Route to player 2 handler if current player is PLAYER_2.

9138

JP Z,inc_player_2_score_digit