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