function [ doubleVAXG ] = uint64le_to_VAXG(uint32le)
%UINT64LE_TO_VAXG Converts from IEEE-LE (UINT32) to VAXG (double)
% This function takes a vector columns of raw 32bit unsigned integers
% (little endian), combines them into 64bit unsigned integers, and
% converts the result into the equivalent floating point numbers using
% the specification for the VAXG floating point number format.
% VAXD and VAXG are two 64bit floating point formats. VAXF is the 32bit
% floating point format used in conjunction with both VAXD and VAXG.
% http://www.opengroup.org/onlinepubs/9629399/chap14.htm#tagfcjh_20
%
% The function is intended to be called from FREADVAXG.
%
% See also UINT32LE_TO_VAXF, UINT64LE_TO_VAXD, FREADVAXD, FREADVAXG
% Copyright 2009-2011 The MathWorks, Inc.
%% Define floating value properties for VAX architecture
% The generic equation for a floating point number is:
% (-1)^double(S) * (F+C) * A^(double(E)-B);
% Different operating systems and file formats utilize different values
% for A, B, and C. F, E, and S are computed from the appropriate bits in
% the number as stored on disk.
A = 2 ;%VAX specific
B = 1024;%VAX specific
C = 0.5 ;%VAX specific
%% Convert raw unsigned number into right answer
% VAX (64bit) <--WORD1--><--WORD2--><--WORD3--><--WORD4-->
% IEEE-LE (32bit) <--WORD2--><--WORD1-->
% IEEE-LE (32bit) <--WORD4--><--WORD3-->
uint32le = reshape(uint32le,2,[])';
uint32leA = uint32le(:,1);
uint32leB = uint32le(:,2);
% Swap WORD1 and WORD2
word2 = bitshift(bitshift(uint32leA, 0), -16);%mask FFFF0000
word1 = bitshift(bitshift(uint32leA, 16), -16);%mask 0000FFFF
vaxIntA = bitor(bitshift(word1,16), bitshift(word2, 0));
% Swap WORD3 and WORD4
word4 = bitshift(bitshift(uint32leB, 0), -16);%mask FFFF0000
word3 = bitshift(bitshift(uint32leB, 16), -16);%mask 0000FFFF
vaxIntB = bitor(bitshift(word3,16), bitshift(word4, 0));
% Create UINT64: <--WORD1--><--WORD2--><--WORD3--><--WORD4-->
vaxIntA = bitshift(uint64(vaxIntA),32);
vaxIntB = uint64(vaxIntB);
vaxInt = bitor(vaxIntA,vaxIntB);
% Pull out the sign, exponent, and fractional component
% VAX FLOAT BYTES <-----WORD1----><-----WORD2----><-----WORD1----><-----WORD2---->
% VAX FLOAT BITS 0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF
% Sign Exp Fract SEEEEEEEEEEEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
S = bitshift(vaxInt, -63);
E = bitshift(bitshift(vaxInt, 1),-53);
F = bitshift(bitshift(vaxInt,12),-12);
% Construct the floating point number from SEF (Sign, Exp, Fract)
% Formula valid for non-zero values only (zeros fixed in next step)
% http://www.codeproject.com/KB/applications/libnumber.aspx
% http://www.opengroup.org/onlinepubs/9629399/chap14.htm#tagfcjh_20
M = C+double(F)./9007199254740992; %VAX Specific 90071992547409924=2^53
doubleVAXG = (-1).^double(S) .* M .* A.^(double(E)-B);%Generic
% Add in zeros (if E and S are zero, doubleVAXG should be set to zero)
zerosIndex = (E == 0 & S == 0);%logical index of all zeros
doubleVAXG(zerosIndex) = 0;
end
