minor comment changes

2016-07-24 14:26:11 +02:00
parent 10b9c13d07
commit 7ed5e33b89
3 changed files with 9 additions and 121 deletions
@@ -194,117 +194,7 @@ void ZSTD_copyDCtx(ZSTD_DCtx* dstDCtx, const ZSTD_DCtx* srcDCtx)
 *   Decompression section
 ***************************************************************/

-/* Frame format description
-   Frame Header -  [ Block Header - Block ] - Frame End
-   1) Frame Header
-      - 4 bytes - Magic Number : ZSTD_MAGICNUMBER (defined within zstd.h)
-      - 1 byte  - Frame Descriptor
-   2) Block Header
-      - 3 bytes, starting with a 2-bits descriptor
-                 Uncompressed, Compressed, Frame End, unused
-   3) Block
-      See Block Format Description
-   4) Frame End
-      - 3 bytes, compatible with Block Header
-*/
-
-
-/* Frame Header :
-
-   1 byte - FrameHeaderDescription :
-   bit 0-1 : dictID (0, 1, 2 or 4 bytes)
-   bit 2   : checksumFlag
-   bit 3   : reserved (must be zero)
-   bit 4   : reserved (unused, can be any value)
-   bit 5   : Single Segment (if 1, WindowLog byte is not present)
-   bit 6-7 : FrameContentFieldSize (0, 2, 4, or 8)
-             if (SkippedWindowLog && !FrameContentFieldsize) FrameContentFieldsize=1;
-
-   Optional : WindowLog (0 or 1 byte)
-   bit 0-2 : octal Fractional (1/8th)
-   bit 3-7 : Power of 2, with 0 = 1 KB (up to 2 TB)
-
-   Optional : dictID (0, 1, 2 or 4 bytes)
-   Automatic adaptation
-   0 : no dictID
-   1 : 1 - 255
-   2 : 256 - 65535
-   4 : all other values
-
-   Optional : content size (0, 1, 2, 4 or 8 bytes)
-   0 : unknown          (fcfs==0 and swl==0)
-   1 : 0-255 bytes      (fcfs==0 and swl==1)
-   2 : 256 - 65535+256  (fcfs==1)
-   4 : 0 - 4GB-1        (fcfs==2)
-   8 : 0 - 16EB-1       (fcfs==3)
-*/
-
-
-/* Compressed Block, format description
-
-   Block = Literal Section - Sequences Section
-   Prerequisite : size of (compressed) block, maximum size of regenerated data
-
-   1) Literal Section
-
-   1.1) Header : 1-5 bytes
-        flags: 2 bits
-            00 compressed by Huff0
-            01 unused
-            10 is Raw (uncompressed)
-            11 is Rle
-            Note : using 01 => Huff0 with precomputed table ?
-            Note : delta map ? => compressed ?
-
-   1.1.1) Huff0-compressed literal block : 3-5 bytes
-            srcSize < 1 KB => 3 bytes (2-2-10-10) => single stream
-            srcSize < 1 KB => 3 bytes (2-2-10-10)
-            srcSize < 16KB => 4 bytes (2-2-14-14)
-            else           => 5 bytes (2-2-18-18)
-            big endian convention
-
-   1.1.2) Raw (uncompressed) literal block header : 1-3 bytes
-        size :  5 bits: (IS_RAW<<6) + (0<<4) + size
-               12 bits: (IS_RAW<<6) + (2<<4) + (size>>8)
-                        size&255
-               20 bits: (IS_RAW<<6) + (3<<4) + (size>>16)
-                        size>>8&255
-                        size&255
-
-   1.1.3) Rle (repeated single byte) literal block header : 1-3 bytes
-        size :  5 bits: (IS_RLE<<6) + (0<<4) + size
-               12 bits: (IS_RLE<<6) + (2<<4) + (size>>8)
-                        size&255
-               20 bits: (IS_RLE<<6) + (3<<4) + (size>>16)
-                        size>>8&255
-                        size&255
-
-   1.1.4) Huff0-compressed literal block, using precomputed CTables : 3-5 bytes
-            srcSize < 1 KB => 3 bytes (2-2-10-10) => single stream
-            srcSize < 1 KB => 3 bytes (2-2-10-10)
-            srcSize < 16KB => 4 bytes (2-2-14-14)
-            else           => 5 bytes (2-2-18-18)
-            big endian convention
-
-        1- CTable available (stored into workspace ?)
-        2- Small input (fast heuristic ? Full comparison ? depend on clevel ?)
-
-
-   1.2) Literal block content
-
-   1.2.1) Huff0 block, using sizes from header
-        See Huff0 format
-
-   1.2.2) Huff0 block, using prepared table
-
-   1.2.3) Raw content
-
-   1.2.4) single byte
-
-
-   2) Sequences section
-      TO DO
-*/
+/* See compression format details in : zstd_compression_format.md */

 /** ZSTD_frameHeaderSize() :
 *   srcSize must be >= ZSTD_frameHeaderSize_min.