= GIET-VM / TTY0 access functions =

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The [source:soft/giet_vm/giet_common/utils.c utils.c] and [source:soft/giet_vm/giet_common/utils.h util.h] files define the functions used to access the kernel terminal TTY[0]. The ''_put*'' functions do not take the lock protecting exclusive access. The ''_printf'' function takes the lock protecting exclusive access.

They are prefixed by "_" to remind that they can only be executed by a processor in kernel mode.

 === void _puts( char* string ) ===
Displays a ''string'' on kernel TTY0. This function does NOT take the TTY0 lock.

 === void _putx( unsigned int value ) ===
Displays a 32 bits word as an hexadecimal string on kernel TTY0. This function does NOT take the TTY0 lock.

=== void _putl( unsigned long long value ) ===
Displays a 64 bits word as an hexadecimal string on kernel TTY0. This function does NOT take the TTY0 lock.

 === void _putd( unsigned int value ) ===
Displays a 32 bits word as an decimal string on kernel TTY0. This function does NOT take the TTY0 lock.

 === void _printf( char* format, ... ) ===
Display a format on kernel TTY0. To provide an atomic display, this function takes the lock protecting
exclusive access to TTY0, entering a critical section until the lock is released.
Only a limited number of formats are supported:
 * %d : 32 bits signed   decimal
 *  %u : 32 bits unsigned decimal
 *  %x : 32 bits unsigned hexa
 *  %l : 64 bits unsigned hexa
 *  %c : char
 *  %s : string

 === void _getc( char* byte ) ===
This blocking function uses a polling strategy on the TTY0 status register to get a single character.