Routines
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63673: Merge Background Byte
Used by the routine at BuildShiftedShapeB.
Merges one byte of the chequered background into the buffer: the pattern byte of 85, shifted by the amount that the table in D gives. The entry point at MergeBackgroundByte_Merge merges A.
Input
D Page of the table of shifted bytes
HL' Address in the buffer
Output
HL' Address of the next byte in the buffer
MergeBackgroundByte 63673 LD E,85 E=85.
63675 LD A,(DE) Read DE.
This entry point is used by the routines at BuildShiftedShapeA and BuildShiftedShapeB.
MergeBackgroundByte_Merge 63676 EXX Switch to the alternate registers.
This entry point is used by the routine at BuildShiftedShapeA.
MergeBackgroundByte_Store 63677 OR (HL) Set the bits of A that are set in the byte at HL.
63678 LD (HL),A Write A where HL points.
63679 INC HL Advance HL.
63680 EXX Switch to the alternate registers.
63681 RET Return.
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