From: Tomas Valla <tom@ucw.cz>
Date: Thu, 28 Mar 2013 13:12:23 +0000 (+0100)
Subject: Varints: Added documentation.
X-Git-Tag: v5.99~83
X-Git-Url: http://mj.ucw.cz/gitweb/?a=commitdiff_plain;h=dd47f287898ea0f976dc1d737eda47d8690e621c;p=libucw.git

Varints: Added documentation.
---

diff --git a/ucw/doc/Makefile b/ucw/doc/Makefile
index 4da7cf8c..7a018f3d 100644
--- a/ucw/doc/Makefile
+++ b/ucw/doc/Makefile
@@ -2,7 +2,7 @@
 
 DIRS+=ucw/doc
 
-UCW_DOCS=basics log fastbuf index config configure install basecode hash docsys conf mempool eltpool mainloop generic growbuf unaligned lists chartype unicode prime binsearch heap binheap compress sort hashtable relnotes trans string time daemon signal
+UCW_DOCS=basics log fastbuf index config configure install basecode hash docsys conf mempool eltpool mainloop generic growbuf unaligned lists chartype unicode prime binsearch heap binheap compress sort hashtable relnotes trans string time daemon signal varint
 UCW_INDEX=$(o)/ucw/doc/def_index.html
 UCW_DOCS_HTML=$(addprefix $(o)/ucw/doc/,$(addsuffix .html,$(UCW_DOCS)))
 
diff --git a/ucw/doc/index.txt b/ucw/doc/index.txt
index e449c755..f8240068 100644
--- a/ucw/doc/index.txt
+++ b/ucw/doc/index.txt
@@ -33,6 +33,7 @@ Modules
 - <<growbuf:,Growing buffers>>
 - <<chartype:,Single-byte characters>>
 - <<unicode:,Multi-byte characters>>
+- <<varint:,Encoding of integers>>
 - <<prime:,Prime numbers>>
 - <<sort:,Sorting>>
 - <<binsearch:,Binary search>>
diff --git a/ucw/doc/varint.txt b/ucw/doc/varint.txt
new file mode 100644
index 00000000..85687bf1
--- /dev/null
+++ b/ucw/doc/varint.txt
@@ -0,0 +1,4 @@
+Efficient encoding of u64 to byte sequence
+==========================================
+
+!!ucw/varint.h
diff --git a/ucw/varint.h b/ucw/varint.h
index 79952dc1..2688a088 100644
--- a/ucw/varint.h
+++ b/ucw/varint.h
@@ -13,15 +13,15 @@
 /***
  * The encoding works in the following way:
  *
- * First byte			Stored values
+ *  First byte			Stored values
  *
- * 0xxxxxxx			7 bits
- * 10xxxxxx  +1 byte		14 bits, value shifted by 2^7
- * 110xxxxx  +2 bytes		21 bits, value shifted by 2^7+2^14
- * 1110xxxx  +3 bytes		28 bits, value shifted by 2^7+2^14+2^21
+ *  0xxxxxxx			7 bits
+ *  10xxxxxx  +1 byte		14 bits, value shifted by 2^7
+ *  110xxxxx  +2 bytes		21 bits, value shifted by 2^7+2^14
+ *  1110xxxx  +3 bytes		28 bits, value shifted by 2^7+2^14+2^21
  *    ....
- * 11111110  +7 bytes		56 bits, value shifted by 2^7+2^14+2^21+2^28+2^35+2^42
- * 11111111  +8 bytes		full 64 bits, value shifted by 2^7+2^14+2^21+2^28+2^35+2^42+2^56
+ *  11111110  +7 bytes		56 bits, value shifted by 2^7+2^14+2^21+2^28+2^35+2^42
+ *  11111111  +8 bytes		full 64 bits, value shifted by 2^7+2^14+2^21+2^28+2^35+2^42+2^56
  *
  * The values are stored in bigendian to allow lexicographic sorting.
  * The encoding and algorithms are aimed to be optimised for storing shorter numbers.