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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) ???? - INRIA - Farid BELAHCENE
// Copyright (C) 2008 - INRIA - Pierre MARECHAL
//
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution. The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2.1-en.txt
function y = bitget(x,pos)
// BITGET function
// Given an unsigned integer x, this function returns an unsigned integer
// (0 or 1) which is the bit number 'pos' from the representation binary of x
// if x=uint8(19) and pos=2 then bitget returns the 2th bit of the binary form of 19 ('10011') which is 1
// -Inputs :
// x : an unsigned integer
// pos : a positive integer between 1 and the bitmax of the x type
//
// -Output :
// y : an unsigned integer
//
// F.Belahcene
// P. Marechal, 5 Feb 2008
// - Add argument check
// Check input arguments
// =========================================================================
// check number input argument
rhs = argn(2);
if rhs <> 2 then
error(msprintf(gettext("%s: Wrong number of input argument(s): %d expected.\n"),"bitget",2));
end
// case empty matrix
if isempty(x)
if ~isempty(pos) & prod(size(pos))<>1
error(msprintf(gettext("%s: Wrong size for input arguments: Same size expected.\n"),"bitget"));
else
y=[]
return
end
end
// check size
if (size(x,"*")>1) & (size(pos,"*")>1) & (or(size(x)<>size(pos))) then
error(msprintf(gettext("%s: Wrong size for input arguments: Same size expected.\n"),"bitget"));
end
// check type
if (type(x)==1 & (x-floor(x)<>0 | x<0)) ..
| (type(x)==8 & (inttype(x)<10)) ..
| (type(x)<>1 & type(x)<>8) then
error(msprintf(gettext("%s: Wrong input argument #%d: Scalar/matrix of unsigned integers expected.\n"),"bitget",1));
end
if (type(pos)==1 & (pos-floor(pos)<>0 | pos<0)) ..
| (type(pos)==8 & (inttype(pos)<10)) ..
| (type(pos)<>1 & type(pos)<>8) then
error(msprintf(gettext("%s: Wrong input argument #%d: Scalar/matrix of unsigned integers expected.\n"),"bitget",2));
end
// check pos value
select inttype(x)
case 0 then posmax = 52;
case 11 then posmax = 8;
case 12 then posmax = 16;
case 14 then posmax = 32;
end
if (pos>posmax) | (pos<1) then
error(msprintf(gettext("%s: Wrong value for input argument #%d: Must be between %d and %d.\n"),"bitget",2,1,posmax));
end
// Algorithm
// =========================================================================
if size(pos,"*") == 1;
pos = ones(x) * pos;
end
if size(x,"*") == 1;
x = ones(pos) * x;
end
if type(x)==8 then
select inttype(x)
case 11 then
mask = uint8(2^(pos-1));
y = uint8(1 * ((x & mask) > 0));
return;
case 12 then
mask = uint16(2^(pos-1));
y = uint16(1 * ((x & mask) > 0));
return;
case 14 then
mask = uint32(2^(pos-1));
y = uint32(1 * ((x & mask) > 0));
return;
end
else
// type == 1
a = 2^32;
mask = uint32(zeros(pos));
ytemp = uint32(zeros(pos));
if or(pos<=32) then
mask( pos<=32 ) = uint32( 2^(pos(pos<=32) -1 ));
ytemp( pos<=32 ) = uint32( x(pos<=32) - double(uint32(x(pos<=32)/a)) * a ); // permet de récupérer les 32 bits de poid faible
end
if or(pos>32) then
mask( pos>32 ) = uint32( 2^(pos(pos>32) -32 -1 ));
ytemp( pos> 32 ) = uint32( x(pos> 32)/a); // permet de récupérer les 32 bits de poid fort
end
y = 1 * ((ytemp & mask) > 0);
end
endfunction
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