Routines
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24790: Convert To Screen Buffer Address
Used by the routines at 24852 and 29597.
On entry HL is a number between 0000-3872 corresponding to the playarea.
ScreenBufferAddress 24790 PUSH AF Stash AF on the stack.
24791 LD A,H A=H.
24792 RRA
24793 RRA
24794 RRA
24795 RRA
24796 AND %11100000 Keep only bits 5-7.
24798 OR L Set the bits from L.
24799 LD C,A C=A.
24800 LD A,H A=H.
24801 AND %00011000 Keep only bits 3 and 4.
24803 OR %01000000 Set bit 6 of B which converts BC to a screen address.
24805 LD B,A
24806 POP AF Retrieve AF from the stack.
24807 RET Return.
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