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/*
* crt0_redboot.S -- Minimal startup file for MN10300 targets running Redboot.
*
* Copyright (c) 2001 Red Hat, Inc.
* Derived from crt0_cygmon.S - Copyright (c) 1995, 1996, 1997, 2000 Red Hat, Inc.
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice is included verbatim in any distributions. No written agreement,
* license, or royalty fee is required for any of the authorized uses.
* Modifications to this software may be copyrighted by their authors
* and need not follow the licensing terms described here, provided that
* the new terms are clearly indicated on the first page of each file where
* they apply.
*/
/*
* This file contains the minimal startup code necessary.
* This will not do any hardware initialization. It is assumed that we are talking to Redboot
* and therefore the hardware will be initialized properly.
*/
/*
* Set up some room for a stack. We just grab a chunk of memory.
*/
#define STACK_SIZE 0x4000
#define GLOBAL_SIZE 0x2000
#define STARTUP_STACK_SIZE 0x0100
.comm __memsize, 12
.comm __lstack, STARTUP_STACK_SIZE
.comm __stackbase,4
.section .text
.global _start
_start:
/*
* Setup a small stack so we can run some C code,
* and get the usable memory size.
*/
mov __lstack,a0
add STARTUP_STACK_SIZE-4,a0
mov a0,sp
/*
* zero out the bss section.
*/
.global __memsize
.global _get_mem_info
zerobss:
mov __bss_start, a0 # These variables are defined in the linker script
mov _end, a1
cmp a0, a1 # If no bss, then do nothing
beq 7f
clr d0
3:
movbu d0,(a0) # Clear a byte and bump pointer
inc a0
cmp a0, a1
bne 3b
7:
/*
* Setup the stack pointer --
* get_mem_info returns the top of memory, so just use that In
* addition, we must subtract 24 bytes for the 3 8 byte
* arguments to main, in case main wants to write them back to
* the stack. The caller is supposed to allocate stack space
* for parameters in registers in the old MIPS ABIs. We must
* do this even though we aren't passing arguments, because
* main might be declared to have them.
* Some ports need a larger alignment for the stack, so we
* subtract 32, which satisifes the stack for the arguments and
* keeps the stack pointer better aligned.
*/
mov __memsize, d0
call _get_mem_info,[],0
sub 32, a0
mov a0, sp
mov __stackbase, a1
mov a0, (a1) # keep this for future ref
call ___main,[],0 # Call __main to run ctors/dtors
clr d0
clr d1
mov d0, (4,sp)
or 0x0800,psw # Enable interrupts
call _main,[],0 # Call main program
call _exit,[],0
/* EOF crt0_redboot.S */
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