What is a open source data store for bare metal Cortex M3 without OS
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I am looking for suggestions for a data store written in C that will compile for ARM Cortex M3 without any operating system.

I want it to be:

 - written in C 
 - preferably free and/or open source 
 - able to be compiled with GCC 
 - works on bare metal processor without operating system or file system support

It can be SQL or not.  I would like something like MongoDB that is compatible with with JSON (i.e. can serialize via JSON in plain C char buffers.)

The needs of the datastore would be to manage data in RAM from a fixed allocation of memory.  No "dynamic" allocation (i.e. no malloc).