c_call

MIPS处理器的bootloader,龙芯就是用的修改过的PMON2

The call Command
call

The call command executes a subroutine.

Format

The format for the call command is:

call adr [-s str|val]..

where:

adr	is the address of the subroutine to be executed.

-s str	is a string argument.

val	is a value to be passed.

The call command calls a function using the standard C calling
convention. The "-s str" 
and val options permit arguments to be passed to the subroutine.

Functional Description

The call command executes a downloaded subroutine, using a jalr instruction
to pass control to the specified address.
This does not affect the existing value of the saved
registers. Instead the subroutine is called directly from C code
without restoring the saved registers. Control returns to PMON
via the usual subroutine return mechanism. 

If the user specifies arguments,
these are passed using the standard C calling convention. If the
"-s" option is specified, the following argument is assumed to be
a string. In this case the address of the string is passed to the
subroutine. If a numerical value is specified in place of the "-s",
it will be evaluated according to the existing rules and passed
to the function. Up to five arguments may be passed.

This command is usually used to provide a method of displaying
application-specific data structures. For example, if your application
has a complex, linked-list data structure, you might find it helpful
to add a function to your program that can display the structure. The
call command can then be used to invoke this function from the
PMON prompt at any time in the execution, even between two single-step
operations.

Examples illustrating the use of the call command follow.

PMON call prstat		Call the function whos name is 'prstat'.

PMON call prrec a0020000+8	Call the function 'prrec' and pass it
				the value 0xa0020008 as the first argument.

PMON call printf -s "hello world"
				Call the function printf and pass it the
				address of the string "hello world".

Files
The call command is located in mon/call.c.

See Also
g command