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C library structure

Conceptually, the C library can be divided into functions that are part of the ISO C standard, for example printf(), and functions that provide support to the ISO C standard.

For example, the following figure shows the C library implementing the function printf() by writing to the debugger console window. This implementation is provided by calling _sys_write(), a support function that executes a semihosting call, resulting in the default behavior using the debugger instead of target peripherals.

Figure 8-1 C library structure