Adding malloc implementation #16
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The `pos_alloc_user_data` and `pos_free_user_data` are meant to hide hardware-related considreations from the user, providing a single low-level interface to allocate memory.
`malloc` and `free` are simple wrapper around `pos_alloc_user_data` and `pos_free_user_data`. They hide the size of the allocated chunk from the user at the beginning of the allocated pointer.
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Reason for the Pull Request
See issue #15,
mallocandfreeare declared in the stdlib header of the pulp-runtime but are not actually implemented as of commit 252cecb.Changes introduced by the Pull Request
This pull request introduces 3 main changes in the codebase:
In alloc_pool.h, two functions were added:
pos_alloc_user_dataandpos_free_user_data. These functions are used to hide from the user the location where the data is allocated, which may change with the hardware (as was the case in pulp-rt, see rt_alloc). That way, thepos_alloc_tstructs are only visible within alloc_pool.c and not exposed to the end user.In alloc_pool.c, I added the implementations for
pos_alloc_user_dataandpos_free_user_data. The preferred locations to put the data are the same as in rt_alloc.In io.c, I added the implementation for
mallocandfree. The implementation is similar to that used in the io.c of pulp-rt in that the size of the allocated chunk is stored before the pointer given to the user.Additional Notes
I tried to keep the same style as the rest of the codebase so that the code would blend in well, and I also reused names from pulp-rt.
I haven't thoroughly tested the code yet, but I should be able to during the week. I can post a small update then if the PR hasn't been merged yet.
Finally, the internal
pos_allocin alloc.c usesintfor the size, whilemallocstores it as auint32_t. I kept that from the original codebase to avoid introducing many changes at once, but it might cause bugs in edge cases where a size >2GB is allocated at once.