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28 lines
841 B
ObjectPascal
28 lines
841 B
ObjectPascal
{$mode objfpc}
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function UTF8CodePointLength(firstbyte: byte): SizeInt;
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var
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firstzerobit: SizeInt;
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begin
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result:=1;
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{ bsr searches for the leftmost 1 bit. We are interested in the
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leftmost 0 bit, so first invert the value
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}
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firstzerobit:=BsrByte(not(firstbyte));
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{ if there is no zero bit or the first zero bit is the rightmost bit
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(bit 0), this is an invalid UTF-8 byte ($ff cannot appear in an
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UTF-8-encoded string, and in the worst case bit 1 has to be zero)
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}
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if (firstzerobit=0) or (firstzerobit=255) then
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exit;
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{ the number of bytes belonging to this code point is
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7-(pos first 0-bit).
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}
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result:=7-firstzerobit;
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end;
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begin
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writeln(UTF8CodePointLength(ord(' ')));
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end.
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