Configuring Console I/O

Console I/O for stdin, stdout, and stderr can be configured in many different ways. The easiest way to configure console I/O is to have it turned off completely. When EWL_CONSOLE_SUPPORT is defined as 0, EWL does not generate source code to construct the stdin, stdout, and stderr streams. Also, calls such as printf() are not placed in the standard C library.

When EWL_CONSOLE_SUPPORT is 1, the console access can be provided in the following ways:

The first way is to have EWL automatically throw away all items read and written to the console by defining EWL_NULL_CONSOLE_ROUTINES.
The second way is to have EWL treat all console I/O as if it were file I/O by defining EWL_FILE_CONSOLE_ROUTINES. Treating the console as file I/O requires configuring the file I/O portion of EWL as described in the previous section. Input and output go through the read_file(), write_file(), and close_file() bottlenecks instead of read_console(), write_console(), and close_console(), respectively.
The third way to provide console access is to define EWL_CONSOLE_SUPPORT as 1 and leave the remainder of the EWL_CONSOLE_FILE_IS_DISK_FILE and EWL_FILE_CONSOLE_ROUTINES flags in their default state, defined as 0. EWL will then call read_console when it needs input (for example from scanf()), write_console() when it wants to send output (for example from printf()), and close_console() when the console is no longer needed. The three routines should be provided in the console_io_plat.c file.

The macros listed in the table below configure the EWL console input/output capabilities.

Table 1. EWL Console Input/Output Management Macros
Macro	Behavior
EWL_CONSOLE_SUPPORT	Defined to 1 if the EWL platform supports console I/O. Defined to 0 if the EWL platform does not support console I/O. Default value is 1.
EWL_BUFFERED_CONSOLE	Defined to 1 if the EWL platform console I/O is buffered. Defined to 0 if the EWL platform console I/O is not buffered. Default value is 1.
EWL_CONSOLE_FILE_IS_DISK_FILE	Defined to 1 if the EWL platform has console I/O, but it is really in a file. Defined to 0 if the EWL platform has traditional console I/O. Default value is 0.
`EWL_CONSOLE_FILE_IS_DISK_FILE`	Defined to 1 if the EWL platform does not perform console I/O. Defined to 0 if the EWL platform performs console I/O. This flag may be set independently of `EWL_CONSOLE_SUPPORT`. However, when `EWL_CONSOLE_SUPPORT` is defined as 0, `EWL_NULL_CONSOLE_ROUTINES` must always be defined as 1. When `EWL_CONSOLE_SUPPORT` is 1 and `EWL_NULL_CONSOLE_ROUTINES` is also 1, all console I/O is ignored. Default value is 0.
`EWL_FILE_CONSOLE_ROUTINES`	Defined to 1 if the EWL platform uses the file I/O read/write/close routines for console I/O instead of using the special console read/write/close routines. Define to 0 if the EWL platform uses the special console read/write/close routines. When `EWL_CONSOLE_FILE_IS_DISK_FILE` is 1, `EWL_FILE_CONSOLE_ROUTINES` must always be 1. Default value is 0.