[Gdal-dev] About dgn format

[Oleg Melnyk]

 Hello ,
  Recently I found interesting lib about dgn format .
 All information is clear except situation with coordinates .
 Can you  help me and explain how  to restore elements 
coordinates. 
 According  Intergraph Standard File Formats lib http://dl1.maptools.org/dl/dgnlib/ref18.pdf 
was really easy parse byte order and found elements weight, style ,color ,type ...
 I met difficulty with coordinates .
 In DGN format documentation coordinates are stored in long integer and 
 long integers are stored with middle-endian byte ordering . (b0,b1,b2,b3 ==> b2,b3,b0,b1)

 In MicroStation was created simple Line (Type 3 ) in level =1,color= 2 ,style=0 ,weight=3 ,
 and coordinates [ 1. 000000 ; 3. 500000 ]
                               [ 7. 000000 ; 3. 500000]
You can see byte order for this component :

[0]= 1 [0x1] [^A]                   00000001  level = 1 and not a complex element 
[1]= 3 [0x3] [^C]                    00000011  Type=3
[2]= 32 [0x20] [ ]
[3]= 0 [0x0] [^@ (NUL)] word 2 WTF = 32 +2 = 34
[4]= 0 [0x0] [^@ (NUL)]
[5]= -128 [128] [0x80] [^À]
[6]= 16 [0x10] [^P]
[7]= 39 [0x27] [']
[8]= 0 [0x0] [^@ (NUL)]
[9]= -128 [128] [0x80] [^À]
[10]= -72 [184] [0xb8] [¸]
[11]= -120 [136] [0x88] [^È]
[12]= 0 [0x0] [^@ (NUL)]
[13]= 0 [0x0] [^@ (NUL)]
[14]= 0 [0x0] [^@ (NUL)]
[15]= 0 [0x0] [^@ (NUL)]
[16]= 1 [0x1] [^A]
[17]= -128 [128] [0x80] [^À]
[18]= 112 [0x70] [p]
[19]= 17 [0x11] [^Q]
[20]= 0 [0x0] [^@ (NUL)]
[21]= -128 [128] [0x80] [^À]
[22]= -72 [184] [0xb8] [¸]
[23]= -120 [136] [0x88] [^È]
[24]= -1 [255] [0xff] [ÿ]
[25]= -1 [255] [0xff] [ÿ]
[26]= -1 [255] [0xff] [ÿ]
[27]= -1 [255] [0xff] [ÿ]
[28]= 0 [0x0] [^@ (NUL)]
[29]= 0 [0x0] [^@ (NUL)]
[30]= 10 [0xa] [^J (LF)]
[31]= 0 [0x0] [^@ (NUL)]
[32]= 0 [0x0] [^@ (NUL)]  word 17  class=0 (Primary )
[33]= 14 [0xe] [^N]                              00001110  H=0 (Line sigment) , R=0 , A=M=N=1 , L=0 
[34]= 24 [0x18] [^X] word 18  00011000 style = 0 ,weight = 3 
[35]= 2 [0x2] [^B]  00000010 color =2 
[36]= 1 [0x1] [^A]                          00000001  start X  .  If  follow the  doc  ==>   1880162305 = 1110000000100010000000000000001
[37]= 0 [0x0] [^@ (NUL)]             00000000                   It looks that no one endian format can change the range 
[38]= 112 [0x70] [p]		       01110000  
[39]= 17 [0x11] [^Q]                      0100001
[40]= 0 [0x0] [^@ (NUL)]           Y    how can I transform this to  3,500000 ? 
[41]= 0 [0x0] [^@ (NUL)]
[42]= -72 [184] [0xb8] [¸]
[43]= -120 [136] [0x88] [^È]
[44]= 0 [0x0] [^@ (NUL)]
[45]= 0 [0x0] [^@ (NUL)]
[46]= 16 [0x10] [^P]
[47]= 39 [0x27] [']
[48]= 0 [0x0] [^@ (NUL)]
[49]= 0 [0x0] [^@ (NUL)]
[50]= -72 [184] [0xb8] [¸]
[51]= -120 [136] [0x88] [^È]
[52]= 7 [0x7] [^G]
[53]= 16 [0x10] [^P]
[54]= -87 [169] [0xa9] [©]
[55]= 81 [0x51] [Q]
[56]= 4 [0x4] [^D]
[57]= 0 [0x0] [^@ (NUL)]
[58]= 97 [0x61] [a]
[59]= 54 [0x36] [6]

   The same trouble I found with angle and 3D coordinate .
 Please explain me how you did this transformation .

Thanks in advance for your time ,

Thanks ,
  Oleg Melnyk