There are two days, " ctrulib "(CTR User Library), originally library development on Nintendo 3DS, passed version 0.5.0. Reminder: To expand on Nintendo 3DS, you must install the DevkitPro toolchains which includes the ctrulib.
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ctrulib
CTR User Library
library for writing user mode arm11 code for the 3DS (CTR)
the goal with this is to create a very straightforward interface with the 3DS's OS. it is not meant to provide higher level functions; to put things in perspective, the purpose of ctrulib would be to sit between the OS and a possible port of SDL rather than replace it.
setup
ctrulib is just a library and needs a toolchain to function. we built ctrulib to be used in conjunction with devkitARM. you may find instructions on how to install devkitARM here : http://devkitpro.org/wiki/Getting_Started
The most recent devkitARM (r43) includes 3DS support and a prebuilt libctru.
To keep up to date with the most recent changes you'll want to checkout ctrulib, build it and install it.