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* Improved generic implementations of Bsf/Bsr. Existing ones were just ugly, BsfQword/BsrQWord producing total of 15 inline expansions 5 levels down and bloating into just a little less than a kilobyte of code (on MIPS). Now it is at most 3 expansions and 21 instructions (84 bytes), 16 and 32 bit routines are branchless.

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git-svn-id: trunk@28575 -
This commit is contained in:
sergei 2014-09-01 16:00:33 +00:00
parent 5471a399e3
commit 98332db7fe
1 changed files with 42 additions and 31 deletions
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73
rtl/inc/generic.inc
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@ -2376,11 +2376,8 @@ function BsrByte(Const AValue: Byte): Byte;
{$ifndef FPC_HAS_INTERNAL_BSF_WORD}
function BsfWord(Const AValue: Word): {$ifdef CPU16}byte{$else}cardinal{$endif};
begin
result:=$ff;
if lo(AValue)<>0 then
result:=BsfByte(lo(AValue))
else if hi(AValue) <> 0 then
result:=BsfByte(hi(AValue))+8
result:=ord(lo(AValue)=0)*8;
result:=result or BsfByte(byte(AValue shr result));
end;
{$endif}
{$endif}
@ -2389,10 +2386,8 @@ function BsfWord(Const AValue: Word): {$ifdef CPU16}byte{$else}cardinal{$endif};
{$ifndef FPC_HAS_INTERNAL_BSR_WORD}
function BsrWord(Const AValue: Word): {$ifdef CPU16}byte{$else}cardinal{$endif};
begin
if hi(AValue)<>0 then
result:=BsrByte(hi(AValue))+8
else
result:=BsrByte(lo(AValue))
result:=ord(AValue>255)*8;
result:=result or BsrByte(byte(AValue shr result));
end;
{$endif}
{$endif}
@ -2400,37 +2395,47 @@ function BsrWord(Const AValue: Word): {$ifdef CPU16}byte{$else}cardinal{$endif};
{$ifndef FPC_HAS_INTERNAL_BSF_DWORD}
{$ifndef FPC_SYSTEM_HAS_BSF_DWORD}
function BsfDWord(Const AValue : DWord): {$ifdef CPU16}byte{$else}cardinal{$endif};
begin
result:=$ff;
if lo(AValue)<>0 then
result:=BsfWord(lo(AValue))
else if hi(AValue) <> 0 then
result:=BsfWord(hi(AValue))+16
end;
var
tmp: DWord;
begin
result:=ord(lo(AValue)=0)*16;
tmp:=AValue shr result;
result:=result or (ord((tmp and $FF)=0)*8);
tmp:=tmp shr (result and 8);
result:=result or BsfByte(byte(tmp));
end;
{$endif}
{$endif}
{$ifndef FPC_HAS_INTERNAL_BSR_DWORD}
{$ifndef FPC_SYSTEM_HAS_BSR_DWORD}
function BsrDWord(Const AValue : DWord): {$ifdef CPU16}byte{$else}cardinal{$endif};
begin
if hi(AValue)<>0 then
result:=BsrWord(hi(AValue))+16
else
result:=BsrWord(lo(AValue))
end;
var
tmp: DWord;
begin
result:=ord(AValue>$FFFF)*16;
tmp:=AValue shr result;
result:=result or (ord(tmp>$FF)*8);
tmp:=tmp shr (result and 8);
result:=result or BsrByte(byte(tmp));
end;
{$endif}
{$endif}
{$ifndef FPC_HAS_INTERNAL_BSF_QWORD}
{$ifndef FPC_SYSTEM_HAS_BSF_QWORD}
function BsfQWord(Const AValue : QWord): {$ifdef CPU16}byte{$else}cardinal{$endif};
var
tmp: DWord;
begin
result:=$ff;
if lo(AValue) <> 0 then
result:=BsfDWord(lo(AValue))
else if hi(AValue) <> 0 then
result:=BsfDWord(hi(AValue)) + 32;
result:=0;
tmp:=lo(AValue);
if (tmp=0) then
begin
tmp:=hi(AValue);
result:=32;
end;
result:=result or BsfDword(tmp);
end;
{$endif}
{$endif}
@ -2438,11 +2443,17 @@ function BsfQWord(Const AValue : QWord): {$ifdef CPU16}byte{$else}cardinal{$endi
{$ifndef FPC_HAS_INTERNAL_BSR_QWORD}
{$ifndef FPC_SYSTEM_HAS_BSR_QWORD}
function BsrQWord(Const AValue : QWord): {$ifdef CPU16}byte{$else}cardinal{$endif};
var
tmp: DWord;
begin
if hi(AValue) <> 0 then
result:=BsrDWord(hi(AValue)) + 32
else
result:=BsrDWord(lo(AValue))
result:=32;
tmp:=hi(AValue);
if (tmp=0) then
begin
tmp:=lo(AValue);
result:=0;
end;
result:=result or BsrDword(tmp);
end;
{$endif}
{$endif}