Datasheet

Semihosting

5.4 Semihosting SWIs

The SWIs listed in Table 5-1 implement the semihosted operations. These operations

are used by C library functions such as

printf()

and

scanf()

. They can be treated as

ATPCS function calls. However, except for r0 that contains the return status, they

restore the registers they are called with before returning.

Some targets provide additional semihosting calls. See the ARM Firmware Suite (AFS)

documentation for details of SWIs provided by AFS.

Table 5-1 Semihosting SWIs

SWI Description

SYS_OPEN (0x01) on page 5-12 Open a file on the host

SYS_CLOSE (0x02) on page 5-14 Close a file on the host

SYS_WRITEC (0x03) on page 5-14 Write a character to the console

SYS_WRITE0 (0x04) on page 5-14 Write a null-terminated string to the console

SYS_WRITE (0x05) on page 5-15 Write to a file on the host

SYS_READ (0x06) on page 5-16 Read the contents of a file into a buffer

SYS_READC (0x07) on page 5-17 Read a byte from the console

SYS_ISERROR (0x08) on page 5-17 Determine if a return code is an error

SYS_ISTTY (0x09) on page 5-18 Check whether a file is connected to an interactive device

SYS_SEEK (0x0A) on page 5-18 Seek to a position in a file

SYS_FLEN (0x0C) on page 5-19 Return the length of a file

SYS_TMPNAM (0x0D) on page 5-19 Return a temporary name for a file

SYS_REMOVE (0x0E) on page 5-20 Remove a file from the host

SYS_RENAME (0x0F) on page 5-20 Rename a file on the host

SYS_CLOCK (0x10) on page 5-21 Number of centiseconds since execution started

SYS_TIME (0x11) on page 5-21 Number of seconds since January 1, 1970

SYS_SYSTEM (0x12) on page 5-22 Pass a command to the host command-line interpreter

SYS_ERRNO (0x13) on page 5-23 Get the value of the C library

errno

variable

SYS_GET_CMDLINE (0x15) on page 5-24 Get the command-line used to call the executable