| ← B7D2 | Map | B85A → |
B803: Sound effect: orb chews the ball
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The sound while the orb chews the ball, a 49-step sequence.
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| chew_counter | B803 | DEFB $00 | Step counter: 0 when the effect is disarmed, otherwise the step it has reached, 1 to 50 | |
| chew_periods | B804 | DEFB $64,$C8 | Never read | |
| B806 | DEFB $6E,$D2,$78,$C8,$96,$C8,$FA,$5A | Pitch period for each step | ||
| B80E | DEFB $E6,$C8,$96,$32,$0C,$78,$46,$5A | |||
| B816 | DEFB $F0,$64,$A0,$64,$50,$78,$A0,$BE | |||
| B81E | DEFB $D2,$64,$C8,$96,$28,$0A,$6E,$96 | |||
| B826 | DEFB $C8,$82,$5A,$96,$C8,$82,$64,$FA | |||
| B82E | DEFB $64,$8C,$28,$50,$1E,$78,$82,$32 | |||
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The 49 played steps start when the orb's chew reaches animation frame 20 and end before the spit.
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| sfx_chew | B836 | LD A,(chew_counter) | Read the step counter; a disarmed effect has nothing to play. | |
| B839 | OR A | |||
| B83A | RET Z | |||
| B83B | CP $32 | The sweep over: clear the counter and stay silent this frame. | ||
| B83D | JR NZ,chew_step | |||
| B83F | XOR A | |||
| B840 | LD (chew_counter),A | |||
| B843 | RET | |||
| chew_step | B844 | INC A | Advance to the next step and store the counter back. | |
| B845 | LD (chew_counter),A | |||
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Each step's pitch comes from the chew table.
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| B848 | LD E,A | Take this step's period byte into D. QUIRK: the table ends one byte below this routine. The last step reaches past its end and takes the routine's own first opcode as the period. | ||
| B849 | LD D,$00 | |||
| B84B | LD HL,chew_periods | |||
| B84E | ADD HL,DE | |||
| B84F | LD D,(HL) | |||
| B850 | LD C,$02 | Two square-wave cycles this frame | ||
| chew_emit | B852 | CALL sound_blip | Emit one cycle at the current period. | |
| B855 | DEC D | Step the period between the two cycles, then loop. | ||
| B856 | DEC C | |||
| B857 | JR NZ,chew_emit | |||
| B859 | RET | |||
| ← B7D2 | Map | B85A → |