Fix <prevlen> related doc in ziplist.c
According to the definition of ZIP_BIG_PREVLEN and other related code, the guard of single byte <prevlen> should be 254 instead of 255.
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202c2ebec4
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@ -53,20 +53,20 @@
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* <prevlen> <encoding>
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*
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* The length of the previous entry, <prevlen>, is encoded in the following way:
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* If this length is smaller than 255 bytes, it will only consume a single
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* If this length is smaller than 254 bytes, it will only consume a single
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* byte representing the length as an unsinged 8 bit integer. When the length
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* is greater than or equal to 255, it will consume 5 bytes. The first byte is
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* set to 255 (FF) to indicate a larger value is following. The remaining 4
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* is greater than or equal to 254, it will consume 5 bytes. The first byte is
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* set to 254 (FE) to indicate a larger value is following. The remaining 4
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* bytes take the length of the previous entry as value.
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*
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* So practically an entry is encoded in the following way:
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*
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* <prevlen from 0 to 254> <encoding> <entry>
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* <prevlen from 0 to 253> <encoding> <entry>
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*
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* Or alternatively if the previous entry length is greater than 254 bytes
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* Or alternatively if the previous entry length is greater than 253 bytes
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* the following encoding is used:
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*
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* 0xFF <4 bytes unsigned little endian prevlen> <encoding> <entry>
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* 0xFE <4 bytes unsigned little endian prevlen> <encoding> <entry>
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*
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* The encoding field of the entry depends on the content of the
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* entry. When the entry is a string, the first 2 bits of the encoding first
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@ -191,10 +191,10 @@
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#include "redisassert.h"
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#define ZIP_END 255 /* Special "end of ziplist" entry. */
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#define ZIP_BIG_PREVLEN 254 /* Max number of bytes of the previous entry, for
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the "prevlen" field prefixing each entry, to be
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represented with just a single byte. Otherwise
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it is represented as FF AA BB CC DD, where
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#define ZIP_BIG_PREVLEN 254 /* ZIP_BIG_PREVLEN - 1 is the max number of bytes of
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the previous entry, for the "prevlen" field prefixing
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each entry, to be represented with just a single byte.
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Otherwise it is represented as FE AA BB CC DD, where
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AA BB CC DD are a 4 bytes unsigned integer
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representing the previous entry len. */
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