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LazUtf8: use PopCnt in Utf8LengthFast if instructionset supports it (currently X86 with -CpCOREI or higher).

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Bart 2021-12-28 16:14:48 +01:00
parent d056a1c9f1
commit 18b5c2d3e2
1 changed files with 7 additions and 0 deletions
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7
components/lazutils/lazutf8.pas
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@ -517,6 +517,9 @@ const
ONEMASK =$0101010101010101;
EIGHTYMASK=$8080808080808080;
{$endif}
{$if defined(CPUX86_HAS_POPCNT)}
{$define CPU_HAS_POPCNT}
{$ENDIF}
var
pnx: PPtrUInt absolute p; // To get contents of text in PtrInt blocks. x refers to 32 or 64 bits
pn8: puint8 absolute pnx; // To read text as Int8 in the initial and final loops
@ -541,9 +544,13 @@ begin
begin
// Count bytes which are NOT the first byte of a character.
nx := ((pnx^ and EIGHTYMASK) shr 7) and ((not pnx^) shr 6);
{$ifdef CPU_HAS_POPCNT}
Result += PopCnt(nx);
{$ELSE CPU_HAS_POPCNT}
{$push}{$overflowchecks off} // "nx * ONEMASK" causes an arithmetic overflow.
Result += (nx * ONEMASK) >> ((sizeof(PtrInt) - 1) * 8);
{$pop}
{$ENDIF CPU_HAS_POPCNT}
inc(pnx);
end;
// Take care of any left-over bytes.