Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Assuming your file is a long bit stream containing 9-bit blocks and you want to output the same stream but with 8-bit blocks (i.e. dropping every 9th bit).</p> <p>You could read 9 bytes at a time (72 bits = eight 9-bit blocks) and then use bit shifting to put these into eight 8-bit blocks.</p> <p>You would need some special processing to handle a file that isn't a multiple of 9 bytes, so this is just a rough guide.</p> <pre><code>procedure TForm1.Button1Click(Sender: TObject); var FSIn: TFileStream; FSOut: TFileStream; InBuffer: array[0..8] of Byte; OutBuffer: array[0..7] of Byte; X: Integer; BytesRead: Integer; BytesToWrite: Integer; begin FSIn := TFileStream.Create('Input.dat', fmOpenRead); FSOut := TFileStream.Create('Output.dat', fmCreate); try for X := 1 to FSIn.Size div 9 do begin FillChar(InBuffer[0], 9, 0); BytesRead := FSIn.Read(InBuffer[0], 9); OutBuffer[0] := InBuffer[0]; OutBuffer[1] := (InBuffer[1] and 127) shl 1 + (InBuffer[2] and 128) shr 7; OutBuffer[2] := (InBuffer[2] and 63) shl 2 + (InBuffer[3] and 192) shr 6; OutBuffer[3] := (InBuffer[3] and 31) shl 3 + (InBuffer[4] and 224) shr 5; OutBuffer[4] := (InBuffer[4] and 15) shl 4 + (InBuffer[5] and 240) shr 4; OutBuffer[5] := (InBuffer[5] and 7) shl 5 + (InBuffer[6] and 248) shr 3; OutBuffer[6] := (InBuffer[6] and 3) shl 6 + (InBuffer[7] and 252) shr 2; OutBuffer[7] := (InBuffer[7] and 1) shl 7 + (InBuffer[8] and 254) shr 1; if BytesRead &lt; 9 then begin // To do - handle case where 9 bytes could not be read from input BytesToWrite := 8; end else BytesToWrite := 8; FSOut.Write(OutBuffer[0], BytesToWrite); end; finally FSIn.Free; FSOut.Free; end; end; </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POParity bit
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USKevin Newman
    1. USKevin Newman
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. CO+1 it can be done more efficient (pointers, asm and the like), but this is pretty ok for not extreme cases.
      singulars
      1. PO
      1. USMarco van de Voort
    2. COLooks like the InBuffer needs to be cleared before each read to handle the case where 9 bytes were not available to be read.
      singulars
      1. PO
      1. USskamradt
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload