Raspberry Pi Bare Bones: Difference between revisions

If you have done C or C++ programming in user-space, you have used a so-called Hosted Environment. Hosted means that there is a C standard library and other useful runtime features. Alternatively, there is the Freestanding version, which is what we are using here. Freestanding means that there is no C standard library, only what we provide ourselves. However, some header files are actually not part of the C standard library, but rather the compiler. These remain available even in freestanding C source code. In this case we use <stddef.h> to get size_t & NULL and <stdint.h> to get the intx_t and uintx_t datatypes which are invaluable for operating systems development, where you need to make sure that the variable is of an exact size (if we used a short instead of uint16_t and the size of short changed, our VGA driver herecode would break!). Additionally you can access the <float.h>, <iso646.h>, <limits.h>, and <stdarg.h> headers, as they are also freestanding. GCC actually ships a few more headers, but these are special purpose.