ilowlevelio(3)

Section: Interp SDK (3)
Updated: 2009-08-23

NAME

ilowlevelio - encapsulates all target-specific I/O used by interp

SYNOPSIS

#include itypes.h
#include ilowlevelio.h

int get_eof( void );
iword map_memory( iword hardware_address, iword length );
int poll_input( void );
void start_time( iword * scratch1, iword * scratch2 );
iword calc_time( iword * scratch1, iword * scratch2 );
void wait_msec( iword wait_time );
ibyte get_char( void );
ibyte *get_input( ibyte * buf, iword max_index );
void put_string( ibyte * buf );
void put_char( ibyte ch );
void put_line( ibyte * buf );

DESCRIPTION

These functions are the I/O portability layer between interp and the hardware, or host operating system (if there is one.)

Interp does not directly call any c library functions that read or write from or to a hardware interface (STDOUT, STDIN, UART, et. al.)

LIST OF FUNCTIONS

Function

Description

get_eof

Returns non-zero if end-of-file (EOF) has been read from the host operating system standard input (stdin.) For stand-alone (no OS) applications, or for use with an operating system that does not support input redirection, this function always returns zero.

map_memory

Returns an address (>0) if the region of count bytes, beginning at hardware_address can be mapped into system memory. The returned address is the proxy address for the mapped hardware. A return value of -1 indicates that the open of the memory driver (/dev/mem) failed. A return value of -2 indicates that the region failed to map. For stand-alone (no OS) applications, or for use with a non-posix operating system, this function returns zero.

poll_input

Returns true (-1) if input is waiting, or false (0) if not. For use with an operating system that does not support input polling, this function always returns zero.

start_time

Initiates measurement of elapsed time. Pointers for two words of static storage are passed for whatever use the implementation requires. The first argument should be a pointer to system constant 26, the second to system constant 27.

calc_time

Stop measuring elapsed time and return the elapsed time in microseconds. The two arguments passed in are the same ones passed to start_time().

wait_msec

Will wait at least wait_time milliseconds before returning.

get_char

Returns the next character (byte) available from the input hardware. If necessary, it waits for data to become available.

get_input

Returns the next line of input (terminated by either a newline or carriage return) as a zero-terminated string (without the carriage control characters) in the buffer provided. It will not transfer more than max_index characters into the buffer. After which it will append the zero byte to terminate the string. If necessary, it waits for data to become available. It returns a pointer to the zero at the end of the string. This facilitates multiple calls, overwriting the string terminator with the next string.

put_string

Outputs a zero-terminated string of literal characters from the buffer provided to the output hardware. Processing of escape character sequences is not supported by this function. If carriage control, numeric string literals, et. al. are needed please refer to the c library's sprintf family of functions. This function does not return until output is finished.

put_char

Outputs one byte to the output hardware. This function does not return until output is finished.

put_line

Output a string of literal characters from the buffer provided. Carriage control (newline) is automatically appended to the string. This function is well suited to output of literal message strings that must have a carriage return at their end. It does not return until output is finished.

SEE ALSO

sprintf(3), feof(3)