Routines
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39842: Calculate Screen Address
Used by the routines at MenuWriteText, DrawChicken, ClockTick, GameStats, SetKeyPositions, DrawRoomFrame, PrepDraw23, PrepDraw2, ClearSprite, PrintScore, PrintStringColour and DrawSidePanel.
ScreenAddress 39842 LD A,L A=L.
39843 RRCA A=A / 8.
39844 RRCA
39845 RRCA
39846 AND %00011111 Keep only bits 0-4.
39848 LD L,A L=A.
39849 LD A,H A=H.
39850 RLCA A=A * 4.
39851 RLCA
39852 AND %11100000 Keep only bits 5-7.
39854 OR L
39855 LD L,A L=A.
39856 LD A,H A=H.
39857 AND %00000111 Keep only bits 0-2.
39859 EX AF,AF' Switch to the shadow AF register.
39860 LD A,H A=H.
39861 RRCA A=A / 8.
39862 RRCA
39863 RRCA
39864 AND %00011000 Keep only bits 3-4.
39866 OR %01000000 Set bit 6.
39868 LD H,A H=A.
39869 EX AF,AF' Switch to the shadow AF register.
39870 OR H
39871 LD H,A H=A.
39872 RET Return.
View the equivalent code in;
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