231 lines
5.5 KiB
ArmAsm
231 lines
5.5 KiB
ArmAsm
|
/*
|
||
|
|
* crt0.S -- startup file for MIPS.
|
||
|
|
*
|
||
|
|
* Copyright (c) 1995, 1996, 1997 Cygnus Support
|
||
|
|
*
|
||
|
|
* 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.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#ifdef __mips16
|
||
|
|
/* This file contains 32 bit assembly code. */
|
||
|
|
.set nomips16
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#include "regs.S"
|
||
|
|
|
||
|
|
/*
|
||
|
|
* 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
|
||
|
|
|
||
|
|
/* This is for referencing addresses that are not in the .sdata or
|
||
|
|
.sbss section under embedded-pic, or before we've set up gp. */
|
||
|
|
#ifdef __mips_embedded_pic
|
||
|
|
# ifdef __mips64
|
||
|
|
# define LA(t,x) la t,x-PICBASE ; daddu t,s0,t
|
||
|
|
# else
|
||
|
|
# define LA(t,x) la t,x-PICBASE ; addu t,s0,t
|
||
|
|
# endif
|
||
|
|
#else /* __mips_embedded_pic */
|
||
|
|
# define LA(t,x) la t,x
|
||
|
|
#endif /* __mips_embedded_pic */
|
||
|
|
|
||
|
|
.comm __memsize, 12
|
||
|
|
.comm __lstack, STARTUP_STACK_SIZE
|
||
|
|
.comm __stackbase,4
|
||
|
|
|
||
|
|
.text
|
||
|
|
.align 2
|
||
|
|
|
||
|
|
/* Without the following nop, GDB thinks _start is a data variable.
|
||
|
|
* This is probably a bug in GDB in handling a symbol that is at the
|
||
|
|
* start of the .text section.
|
||
|
|
*/
|
||
|
|
nop
|
||
|
|
|
||
|
|
.globl _start
|
||
|
|
.ent _start
|
||
|
|
_start:
|
||
|
|
.set noreorder
|
||
|
|
#ifdef __mips_embedded_pic
|
||
|
|
PICBASE = .+8
|
||
|
|
bal PICBASE
|
||
|
|
nop
|
||
|
|
move s0,$31
|
||
|
|
#endif
|
||
|
|
#if __mips < 3
|
||
|
|
#define STATUS_MASK (SR_CU1|SR_PE)
|
||
|
|
#else
|
||
|
|
# For mips3 or mips4, turn on 64-bit addressing and additional float regs
|
||
|
|
#define STATUS_MASK (SR_CU1|SR_PE|SR_FR|SR_KX|SR_SX|SR_UX)
|
||
|
|
#endif
|
||
|
|
li v0, STATUS_MASK
|
||
|
|
mtc0 v0, C0_SR
|
||
|
|
mtc0 zero, C0_CAUSE
|
||
|
|
nop
|
||
|
|
|
||
|
|
/* Check for FPU presence. Don't check if we know that soft_float is
|
||
|
|
being used. (This also avoids illegal instruction exceptions.) */
|
||
|
|
|
||
|
|
#ifndef __mips_soft_float
|
||
|
|
li t2,0xAAAA5555
|
||
|
|
mtc1 t2,fp0 /* write to FPR 0 */
|
||
|
|
mtc1 zero,fp1 /* write to FPR 1 */
|
||
|
|
mfc1 t0,fp0
|
||
|
|
mfc1 t1,fp1
|
||
|
|
nop
|
||
|
|
bne t0,t2,1f /* check for match */
|
||
|
|
nop
|
||
|
|
bne t1,zero,1f /* double check */
|
||
|
|
nop
|
||
|
|
j 2f /* FPU is present. */
|
||
|
|
nop
|
||
|
|
#endif
|
||
|
|
1:
|
||
|
|
/* FPU is not present. Set status register to say that. */
|
||
|
|
li v0, (STATUS_MASK-(STATUS_MASK & SR_CU1))
|
||
|
|
mtc0 v0, C0_SR
|
||
|
|
nop
|
||
|
|
2:
|
||
|
|
|
||
|
|
|
||
|
|
/* Fix high bits, if any, of the PC so that exception handling
|
||
|
|
doesn't get confused. */
|
||
|
|
LA (v0, 3f)
|
||
|
|
jr v0
|
||
|
|
nop
|
||
|
|
3:
|
||
|
|
LA (gp, _gp) # set the global data pointer
|
||
|
|
.end _start
|
||
|
|
|
||
|
|
/*
|
||
|
|
* zero out the bss section.
|
||
|
|
*/
|
||
|
|
.globl __memsize
|
||
|
|
.globl get_mem_info .text
|
||
|
|
.globl __stack
|
||
|
|
.globl __global
|
||
|
|
.globl zerobss
|
||
|
|
.ent zerobss
|
||
|
|
zerobss:
|
||
|
|
LA (v0, _fbss)
|
||
|
|
LA (v1, _end)
|
||
|
|
3:
|
||
|
|
sw zero,0(v0)
|
||
|
|
bltu v0,v1,3b
|
||
|
|
addiu v0,v0,4 # executed in delay slot
|
||
|
|
|
||
|
|
la t0, __lstack # make a small stack so we
|
||
|
|
addiu sp, t0, STARTUP_STACK_SIZE # can run some C code
|
||
|
|
la a0, __memsize # get the usable memory size
|
||
|
|
jal get_mem_info
|
||
|
|
nop
|
||
|
|
|
||
|
|
/* setup the stack pointer */
|
||
|
|
LA (t0, __stack) # is __stack set ?
|
||
|
|
bne t0,zero,4f
|
||
|
|
nop
|
||
|
|
|
||
|
|
/* NOTE: a0[0] contains the amount of memory available, and
|
||
|
|
not the last memory address. */
|
||
|
|
lw t0,0(a0) # last address of memory available
|
||
|
|
la t1,K0BASE # cached kernel memory
|
||
|
|
addu t0,t0,t1 # get the end of memory address
|
||
|
|
/* 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. */
|
||
|
|
subu t0,t0,32 # and generate a starting stack-pointer
|
||
|
|
4:
|
||
|
|
move sp,t0 # set stack pointer
|
||
|
|
sw sp,__stackbase # keep this for future ref
|
||
|
|
.end zerobss
|
||
|
|
|
||
|
|
/*
|
||
|
|
* initialize target specific stuff. Only execute these
|
||
|
|
* functions it they exist.
|
||
|
|
*/
|
||
|
|
.globl hardware_init_hook .text
|
||
|
|
.globl software_init_hook .text
|
||
|
|
.globl __do_global_dtors .text
|
||
|
|
.globl atexit .text
|
||
|
|
.globl exit .text
|
||
|
|
.globl init
|
||
|
|
.ent init
|
||
|
|
init:
|
||
|
|
LA (t9, hardware_init_hook) # init the hardware if needed
|
||
|
|
beq t9,zero,6f
|
||
|
|
nop
|
||
|
|
jal t9
|
||
|
|
nop
|
||
|
|
6:
|
||
|
|
LA (t9, software_init_hook) # init the hardware if needed
|
||
|
|
beq t9,zero,7f
|
||
|
|
nop
|
||
|
|
jal t9
|
||
|
|
nop
|
||
|
|
7:
|
||
|
|
LA (a0, __do_global_dtors)
|
||
|
|
jal atexit
|
||
|
|
nop
|
||
|
|
|
||
|
|
#ifdef GCRT0
|
||
|
|
.globl _ftext
|
||
|
|
.globl _extext
|
||
|
|
LA (a0, _ftext)
|
||
|
|
LA (a1, _etext)
|
||
|
|
jal monstartup
|
||
|
|
nop
|
||
|
|
#endif
|
||
|
|
|
||
|
|
move a0,zero # set argc to 0
|
||
|
|
jal main # call the program start function
|
||
|
|
nop
|
||
|
|
|
||
|
|
# fall through to the "exit" routine
|
||
|
|
jal exit # call libc exit to run the G++
|
||
|
|
# destructors
|
||
|
|
move a0,v0 # pass through the exit code
|
||
|
|
.end init
|
||
|
|
|
||
|
|
/*
|
||
|
|
* _exit -- Exit from the application. Normally we cause a user trap
|
||
|
|
* to return to the ROM monitor for another run. NOTE: This is
|
||
|
|
* the only other routine we provide in the crt0.o object, since
|
||
|
|
* it may be tied to the "_start" routine. It also allows
|
||
|
|
* executables that contain a complete world to be linked with
|
||
|
|
* just the crt0.o object.
|
||
|
|
*/
|
||
|
|
.globl _exit
|
||
|
|
.ent _exit
|
||
|
|
_exit:
|
||
|
|
7:
|
||
|
|
#ifdef GCRT0
|
||
|
|
jal _mcleanup
|
||
|
|
nop
|
||
|
|
#endif
|
||
|
|
# break instruction can cope with 0xfffff, but GAS limits the range:
|
||
|
|
break 1023
|
||
|
|
nop
|
||
|
|
b 7b # but loop back just in-case
|
||
|
|
nop
|
||
|
|
.end _exit
|
||
|
|
|
||
|
|
/* EOF crt0.S */
|