Nonlibc - module overview

This document gives a quick overview of each module/sub-library included in nonlibc.

fast, reliable 32-bit AND 64-bit hashing - fnv.h

If you need a non-crypto hash, odds are you want FNV1A.

This is the simplest, least-hassle implementation I know of.

Usage examples in fnv_test.c.

An fnvsum utility is also provided for hashing files (or stdin), on the pattern of md5sum. See the fnvsum man page

If you would like to use fnvsum without installing:

$ make
$ # hash stdin:
$ echo -n '' | build-release/util/fnvsum
cbf29ce484222325  -
$ # hash a file:
$ build-release/util/fnvsum /path/to/some/file

straightforward integer math - nmath.h

Sometimes what you DON’T want is floating-point math.

This library has sane implementations for:

• integer ceiling division (i.e.: if not evenly divisible, return +1)
• get the next power of 2 (or current number if a power of 2)
• return the next higher multiple of a number (or itself if evenly divisible)
• get the position of the lowest ‘1’ bit in an integer

Oh, and they’re all inlines so your compiler can reason about local variables and turn out decent assembly.

Every function is shown used in nmath_test.c

generating and parsing hexadecimal strings vis-a-vis integers and bytefields

That’s done by hx2b.h and b2hx.h.

Check out hex2bin2hex_test.c for the full monte.

proper RNG which isn’t a hassle to set-up and use - pcg_rand.h

This is a simple, clean, fast implementation of PCG.

That matters more than you may think - and anyways this API is simple and clean.

Check out the test code at pcg_rand_test.c.

a very fast growing LIFO - lifo.h

The fastest possible way I know to push/pop pointer-sized values onto a stack, which grows (reallocates memory) as necessary, and can be kept around between function calls.

accurately timing blocks of code

Use the nlc_timing_start() and nlc_timing_stop() macros in nonlibc.h.

See e.g.: fnv_test.c for usage examples.

Control flow; print mechanics - zed_dbg.h

This header helps with the following annoyances:

• forgetting to insert a ‘\n’ at the end of an impromptu debug printf statement
• spending time commenting/uncommenting print statements, no easy way to enable/disable entire categories or sets of prints
• printfs inside conditionals increase code size for no good reason
• program throws an error, but forgot to write a print there
• program throws an error and does do a print, but you have to grep for it because you don’t remember which source file it was in
• kryptonite print statements full of CPP kudge like __FILE__ and __LINE__
• complex control flow in functions handling external state e.g. malloc(), open(), fork()
• time spent making print output marginally legible so the Dev Ops people don’t poison your coffee
• needing to pretty-print large arrays of bytes in hex, for post-mortem analysis

Some usage examples are in zed_dbg_test.c; zed_dbg.h itself is fairly well commented also.

Zero-copy I/O - nmem.h

A memory allocator which handles zero-copy I/O behind-the-scenes.

An example usage is the ncp utility provided by this library.

ncp re-implements the system cp command using this library for zero-copy I/O; and is >20% faster than cp for large files.

epoll tracking

TODO

other odds-and-ends

• visibility and inlining macros in nonlibc.h
• some lock-free/atomics in atop.h