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33 lines
515 B
NASM
33 lines
515 B
NASM
NUM_SQUARE_ROOTS EQU 255
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GetSquareRoot: ; 13b87
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; Return the square root of de in b.
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; Rather than calculating the result, we take the index of the
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; first value in a table of squares that isn't lower than de.
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ld hl, .Squares
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ld b, 0
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.loop
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; Make sure we don't go past the end of the table.
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inc b
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ld a, b
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cp NUM_SQUARE_ROOTS
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ret z
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; Iterate over the table until b**2 >= de.
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ld a, [hli]
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sub e
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ld a, [hli]
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sbc d
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jr c, .loop
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ret
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.Squares: ; 13b98
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x = 1
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rept NUM_SQUARE_ROOTS
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dw x * x
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x = x + 1
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endr
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