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Code: Select all

program testbitscan;

function test_byte: boolean;
var
  x8,f,r: byte;
  i: integer;
begin
  for i:=0 to 7 do
  begin
    x8:=1 shl i;
    f:=BsfByte(x8);
    if (f<>i) then
    begin
      writeln('BsfByte(',x8,') returned ',f,', should be ',i);
      exit(false);
    end;
    r:=BsrByte(x8);
    if r<>i then
    begin
      writeln('BsrByte(',x8,') returned ',f,', should be ',i);
      exit(false);
    end;
  end;
  result:=true;
end;

function test_word: boolean;
var
  x16: word;
  i,f,r: integer;
begin
  for i:=0 to 15 do
  begin
    x16:=1 shl i;
    f:=BsfWord(x16);
    if (f<>i) then
    begin
      writeln('BsfWord(',x16,') returned ',f,', should be ',i);
      exit(false);
    end;
    r:=BsrWord(x16);
    if r<>i then
    begin
      writeln('BsrWord(',x16,') returned ',f,', should be ',i);
      exit(false);
    end;
  end;
  result:=true;
end;

function test_dword: boolean;
var
  x32: cardinal;
  i,f,r: integer;
begin
  for i:=0 to 31 do
  begin
    x32:=1 shl i;
    f:=BsfDWord(x32);
    if (f<>i) then
    begin
      writeln('BsfDWord(',x32,') returned ',f,', should be ',i);
      exit(false);
    end;
    r:=BsrDWord(x32);
    if r<>i then
    begin
      writeln('BsrDWord(',x32,') returned ',f,', should be ',i);
      exit(false);
    end;
  end;
  result:=true;
end;

function test_qword: boolean;
var
  x64: qword;
  i, f, r: integer;
begin
  for i:=0 to 63 do
  begin
    x64:=uint64(1) shl i;
    f:=BsfQWord(x64);
    if f<>i then begin
      writeln('BsfQWord(',x64,') returned ',f,', should be ',i);
      exit(false);
    end;
    r:=BsrQWord(x64);
    if r<>i then begin
      writeln('BsrQWord(',x64,') returned ',r,', should be ',i);
      exit(false);
    end;
  end;
  result:=true;
end;

begin
  if test_byte then writeln('passed') else writeln('failed');
  if test_word then writeln('passed') else writeln('failed');
  if test_dword then writeln('passed') else writeln('failed');
  if test_qword then writeln('passed') else writeln('failed');
end.

Code: Select all

function BsfQWord(Const AValue : QWord): cardinal; assembler; nostackframe;
asm
     bsfl    4(%esp),%eax
     jnz     .L2
.L1: bsfl    8(%esp),%eax
     add     $32,%eax
.L2:
end;

function BsrQWord(Const AValue : QWord): cardinal; assembler; nostackframe;
asm
     bsrl    8(%esp),%eax
     jz     .L1
     add     $32,%eax
     jmp     .L2
.L1: bsrl    4(%esp),%eax
.L2:
end;