Defined in stdlib.h, this function performs
a consistency check on the heap. It outputs full information about
every free block if the verbose parameter
is nonzero. Otherwise, it only outputs errors.
The function outputs its results by calling the output function dprint(),
that must work like fprintf(). The first parameter
passed to dprint() is the supplied pointer param.
You can pass fprintf() itself, provided you
cast it to the right function pointer type. This type is defined
as a typedef for convenience. It is called __heapprt.
For example:
Note
If you call fprintf() on a stream that
you have not already sent output to, the library calls malloc() internally
to create a buffer for the stream. If this happens in the middle
of a call to __heapvalid(), the heap might
be corrupted. You must therefore ensure you have already sent some
output to stderr. The code in Example 2 fails if you have
not already written to the stream.
This function is not part of the C library standard, but is supported by the ARM C library as an extension.
Syntax
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