Routines
Prev: 8506 Up: Map Next: 853D
851E: Calculate Screen Address
Used by the routines at MenuWriteText, 86A1, 8826, DisplayPlayerLives, PrintStringColour, 8A5C, DrawGauge, LaserBeam_Animate, A993, HallOfFame and PrintPlayerLevels.
ScreenAddress 851E LD A,L A=L.
851F RRCA A=A / 08.
8520 RRCA
8521 RRCA
8522 AND %00011111 Keep only bits 0-4.
8524 LD L,A L=A.
8525 LD A,H A=H.
8526 RLCA A=A * 04.
8527 RLCA
8528 AND %11100000 Keep only bits 5-7.
852A OR L
852B LD L,A L=A.
852C LD A,H A=H.
852D AND %00000111 Keep only bits 0-2.
852F EX AF,AF' Switch to the shadow AF register.
8530 LD A,H A=H.
8531 RRCA A=A / 08.
8532 RRCA
8533 RRCA
8534 AND %00011000 Keep only bits 3-4.
8536 OR %01000000 Set bit 6.
8538 LD H,A H=A.
8539 EX AF,AF' Switch to the shadow AF register.
853A OR H
853B LD H,A H=A.
853C RET Return.
View the equivalent code in;
Prev: 8506 Up: Map Next: 853D