source: trunk/ToBeReviewed/LECTURE/binary.pro @ 44

function binary, number
;+
; Name:
;   binary
; Purpose:
;   Returns the binary representation of a number of any numerical type.
; Argument:
;   number   scalar or array of numbers (any numerical type)
; Returns:
;   Byte array with binary representation of numbers.
; Examples:
;   Binary representation of 11b:
;     IDL> print, binary(11b)
;     0 0 0 0 1 0 1 1
;   Binary representation of pi (x86: Little-endian IEEE representation):
;     IDL> print, format='(z9.8,5x,4(1x,8i1))', long(!pi,0), binary(!pi)
;      40490fdb      01000000 01001001 00001111 11011011 (x86 Linux)
;      0fdb4149      00001111 11011011 01000001 01001001 (Alpha OpenVMS)
;     IDL> print, format='(8(1x,8i0))', binary(!dpi)
;      01000000 00001001 00100001 11111011 01010100 01000100 00101101 00011000
;   Some first tests before type double was added:
;     print, format='(2a6,4x,2z9.8,4x,8z3.2)', $
;       !version.arch, !version.os, long(!dpi,0,2), byte(!dpi,0,8)
;       x86 linux     54442d18 400921fb     18 2d 44 54 fb 21 09 40
;     sparc sunos     400921fb 54442d18     40 09 21 fb 54 44 2d 18
;     alpha   vms     0fda4149 68c0a221     49 41 da 0f 21 a2 c0 68
;     (Beginning with IDL 5.1, Alpha VMS uses IEEE representation as well.)
; Modification history:
;    19 Dec 1997  Originally a news posting by David Fanning.
;                       (Re: bits from bytes)
;    20 Dec 1997  "Complete" rewrite: eliminate loops.
;    22 Dec 1997  Bit shift instead of exponentiation, return byte
;      array, handle input arrays.
;      Think about double and complex types.
;    22 Sep 1998  Complete rewrite: reduce every numerical type to
;      single bytes. Check that big and little endian machines
;      return exactly the same results (if IEEE).
;    7 May 2003     Added newish data types, unsigned and long64.  BT
;-
  s = size(number)
  type = s[s[0] + 1]
  n_no = s[s[0] + 2]
; Numerical types: (will have to be completed if IDL adds double-long, ...)
; 1: byte             (1-byte unsigned integer)
; 2: integer          (2-byte   signed integer)
; 3: long             (4-byte   signed integer)
; 4: floating-point   (4-byte, single precision)
; 5: double-precision (8-byte, double precision)
; 6: complex        (2x4-byte, single precision)
; 9: double-complex (2x8-byte, double precision)
; 12: uInt      (2-byte, unsigned integer)
; 13: uLong     (4-byte, unsigned integer)
; 14: Long64       (8-byte, signed integer)
; 15: uLong64      (8-byte, unsigned integer)
; Non-numerical types:
; 0: undefined, 7: string, 8: structure, 10: pointer, 11: object reference
;  nbyt = [0, 1, 2, 4, 4, 8, 8, 0, 0, 16, 0, 0] ; number of bytes per type
; code = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
  nbyt = [0, 1, 2, 4, 4, 8, 8, 0, 0, 16, 0, 0,  2,  4,  8,  8]
  ntyp = nbyt[type]
  if ntyp eq 0 then message, 'Invalid argument (must be numerical type).'
  bits = [128, 64, 32, 16,  8,  4,  2,  1] ; = ishft(1b, 7-indgen(8))
; For correct array handling and byte comparison, 'number' and 'bits' require
; same dimensions -> numvalue and bitvalue
  bitvalue = ((bits)[*, intarr(ntyp)])[*, *, intarr(n_no)]
  little_endian = (byte(1, 0, 1))[0]
; In case of complex type and little endian machine, swap the two float values
; before the complete second dimension is reversed at returning.
  if (type eq 6 or type eq 9) and little_endian then $ ; type complex
    numvalue = reform((byte([number], 0, 1, ntyp/2, 2, n_no))$
                      [intarr(8), *, [1,0], *], 8, ntyp, n_no) $
  else numvalue = (byte([number], 0, 1, ntyp, n_no))[intarr(8), *, *]
; On little endian machines, the second dimension of the return value must
; be reversed.
  if little_endian AND type NE 1 then $
    return, reverse((numvalue and bitvalue) ne 0, 2) else $
    return,         (numvalue and bitvalue) ne 0
end