Routines
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52003: Shift View Right Byte
Shifts the screen buffer to the right by one byte, by using the stack pointer to copy it. The part from ShiftViewRightByte_Copy is also used to move rows down by MoveRowsDown.
ShiftViewRightByte 52003 LD (23770),SP Save the stack pointer.
52007 LD HL,61881 Point HL at the last two bytes of the screen buffer.
52010 LD SP,HL Point the stack at them.
52011 POP DE Skip those two bytes, which the shift overwrites.
52012 LD B,128 Set the row count to 128.
This entry point is used by the routine at MoveRowsDown.
ShiftViewRightByte_Copy 52014 LD D,(HL) Copy the twenty-four bytes of the next row onto the stack, walking backwards.
52015 DEC HL
52016 LD E,(HL)
52017 DEC HL
52018 PUSH DE
52019 LD D,(HL)
52020 DEC HL
52021 LD E,(HL)
52022 DEC HL
52023 PUSH DE
52024 LD D,(HL)
52025 DEC HL
52026 LD E,(HL)
52027 DEC HL
52028 PUSH DE
52029 LD D,(HL)
52030 DEC HL
52031 LD E,(HL)
52032 DEC HL
52033 PUSH DE
52034 LD D,(HL)
52035 DEC HL
52036 LD E,(HL)
52037 DEC HL
52038 PUSH DE
52039 LD D,(HL)
52040 DEC HL
52041 LD E,(HL)
52042 DEC HL
52043 PUSH DE
52044 LD D,(HL)
52045 DEC HL
52046 LD E,(HL)
52047 DEC HL
52048 PUSH DE
52049 LD D,(HL)
52050 DEC HL
52051 LD E,(HL)
52052 DEC HL
52053 PUSH DE
52054 LD D,(HL)
52055 DEC HL
52056 LD E,(HL)
52057 DEC HL
52058 PUSH DE
52059 LD D,(HL)
52060 DEC HL
52061 LD E,(HL)
52062 DEC HL
52063 PUSH DE
52064 LD D,(HL)
52065 DEC HL
52066 LD E,(HL)
52067 DEC HL
52068 PUSH DE
52069 LD D,(HL)
52070 DEC HL
52071 LD E,(HL)
52072 DEC HL
52073 PUSH DE
52074 DJNZ ShiftViewRightByte_Copy Decrease the row count and jump back until every row has been copied.
52076 LD SP,(23770) Restore the stack pointer.
52080 RET Return.
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