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@@ -61,7 +61,7 @@ Internals
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Log of key-value pairs
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~~~~~~~~~~~~~~~~~~~~~~
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-NVS stores key-value pairs sequentially, with new key-value pairs being added at the end. When a value of any given key has to be updated, old key-value pair is marked as erased and new key-value pair is added at the end of the log.
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+NVS stores key-value pairs sequentially, with new key-value pairs being added at the end. When a value of any given key has to be updated, new key-value pair is added at the end of the log and old key-value pair is marked as erased.
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Pages and entries
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~~~~~~~~~~~~~~~~~
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@@ -69,10 +69,10 @@ Pages and entries
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NVS library uses two main entities in its operation: pages and entries. Page is a logical structure which stores a portion of the overall log. Logical page corresponds to one physical sector of flash memory. Pages which are in use have a *sequence number* associated with them. Sequence numbers impose an ordering on pages. Higher sequence numbers correspond to pages which were created later. Each page can be in one of the following states:
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Empty/uninitialized
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- Flash storage for the page is empty (all bytes are ``0xff``). Page isn't used to store any data at this point and doesn’t have
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+ Flash storage for the page is empty (all bytes are ``0xff``). Page isn't used to store any data at this point and doesn’t have a sequence number.
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Active
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- Flash storage is initialized, page header has been written to flash, page has a valid sequence number. Page has some empty entries and data can be written there. Normally only one page can be in this state.
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+ Flash storage is initialized, page header has been written to flash, page has a valid sequence number. Page has some empty entries and data can be written there. At most one page can be in this state at any given moment.
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Full
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Flash storage is in a consistent state and is filled with key-value pairs.
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@@ -213,7 +213,7 @@ As mentioned above, each key-value pair belongs to one of the namespaces. Namesp
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+-------------------------------------------+
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| NS=0 Type=uint8_t Key="pwm" Value=2 | Entry describing namespace "pwm"
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+-------------------------------------------+
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- | NS=0 Type=uint16_t Key="channel" Value=20 | Key "channel" in namespace "pwm"
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+ | NS=2 Type=uint16_t Key="channel" Value=20 | Key "channel" in namespace "pwm"
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+-------------------------------------------+
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Ivan Grokhotkov