c_g.htm

mips架构的bootloader,99左右的版本 但源代码现在没人更新了

<title>The g Command</title>
<h1>g</h1>

<!--INDEX "g command" go "start execution" -->

The g command starts program execution.<p>

</dl><h2>Format</h2><dl><dd>

The format for the g command is:<p>

<pre>
g [-st] [adr [bptadr]] [-c args-]
</pre>

where:<p>

<dl compact>
<dt>
-s	<dd>is a flag indicating that the stack pointer, sp, should not be set.

<dt>
-t	<dd>is a flag that causes the execution time of the client program 
	to be displayed in seconds.

<dt>
adr	<dd>is the address of the first instruction to be executed.

<dt>
bptadr	<dd>is a breakpoint address where program execution is to be 
	stopped. This breakpoint is removed the next time that 
	execution halts.

<dt>
-c args	<dd>indicates that the argument or arguments args are to be 
	passed to the client program.
</dl><p>

By default, the g command starts program execution at the address in the 
EPC register, and sets the stack pointer, sp, to the beginning of the stack 
area.<p>

</dl><h2>Functional Description</h2><dl><dd>

The g command starts program execution. If the user does not specify the 
starting address adr, execution starts at the current value of the EPC 
register. This command must only be used once after downloading
a new program. Use the <a href="c_c.htm">c</a> command to continue 
execution after a breakpoint.<p>

If the user specifies the -c option, the <a
href="mondef.htm">Monitor</a> passes all arguments after -c to the
client program by the following method. If -c is specified, the <a
href="mondef.htm">Monitor</a> places the number of arguments (argc) in
Register a0. The <a href="mondef.htm">Monitor</a> also places the
address of an array of pointers to the command argument-strings in
Register a1. The first element in the array pointed to by a1 contains a
pointer to the string -c (the option on the command line).  Note that
if the -c is not specified, register a0 will be set to zero.<p>

If adr is specified, a temporary <a href="brkpts.htm">breakpoint</a>
(bptadr) may also be specified.  The temporary breakpoint remains in
effect only until the next time that program execution is halted. The
character '.' may be used as a placeholder for the adr if you wish to
specifiy a temporary breakpoint without specifying a start address.<p>

If you use the standard start-up file for executing programs under the
control of the PROM <a href="mondef.htm">Monitor</a>, the function
main will receive two incoming arguments, argc and argv, having the
correct values to permit a program to read options from the command
line, where argv[0] is a pointer to the string -c. <p>

Note that a program built using version 4.0 of pmcc will not execute under 
pre-3.0 versions of  the PROM Monitor unless the -c option is specified in 
the g command.<p>

Examples illustrating the use of the g command follow.<p>

<pre>
PMON> g				Start executing at the current value of 
				the EPC register.

PMON> g a0020000		Start executing at 0xa0020000.

PMON> g a0020000 a0020008	Start executing at 0xa0020000 and 
				break at 0xa0020008.
</pre>

</dl><h2>Files</h2><dl><dd>
The g command is located in <a href="../mon/go.c">mon/go.c</a>.

</dl><h2>See Also</h2><dl><dd>
<a href="c_c.htm">c command</a>
</dl><p><hr>
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