forked from Imagelibrary/rtems
bsps: Move start files to bsps
This patch is a part of the BSP source reorganization. Update #3285.
This commit is contained in:
Sebastian Huber
196
bsps/mips/jmr3904/start/start.S
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196
bsps/mips/jmr3904/start/start.S
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@@ -0,0 +1,196 @@
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/*
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* start.S -- startup file for JMR3904 BSP based upon crt0.S from
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* newlib-1.8.2/libgloss/mips and adapted for RTEMS.
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*
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* crt0.S -- startup file for MIPS.
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*
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* Copyright (c) 1995, 1996, 1997 Cygnus Support
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*
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* The authors hereby grant permission to use, copy, modify, distribute,
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* and license this software and its documentation for any purpose, provided
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* that existing copyright notices are retained in all copies and that this
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* notice is included verbatim in any distributions. No written agreement,
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* license, or royalty fee is required for any of the authorized uses.
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* Modifications to this software may be copyrighted by their authors
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* and need not follow the licensing terms described here, provided that
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* the new terms are clearly indicated on the first page of each file where
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* they apply.
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*/
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#include <rtems/asm.h>
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#include <bsp/regs.h>
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#ifdef __mips16
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/* This file contains 32 bit assembly code. */
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.set nomips16
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#endif
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/* This is for referencing addresses that are not in the .sdata or
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.sbss section under embedded-pic, or before we've set up gp. */
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#ifdef __mips_embedded_pic
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# ifdef __mips64
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# define LA(t,x) la t,x-PICBASE ; daddu t,s0,t
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# else
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# define LA(t,x) la t,x-PICBASE ; addu t,s0,t
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# endif
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#else /* __mips_embedded_pic */
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# define LA(t,x) la t,x
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#endif /* __mips_embedded_pic */
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.text
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.align 2
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/* Without the following nop, GDB thinks _start is a data variable.
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* This is probably a bug in GDB in handling a symbol that is at the
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* start of the .text section.
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*/
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nop
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.globl _start
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.ent _start
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_start:
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.set noreorder
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/* Get the address of start into $5 in a position independent fashion.
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** This lets us know whether we have been relocated or not.
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*/
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$LF1 = . + 8
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bal $LF1
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nop
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_branch:
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move $5, $31 # $5 == where are we
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li $6, 0x8800000c # $6 == where we want to be
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/* #la $6,_branch */
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beq $5, $6, _start_in_ram
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nop
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/* relocate the code from EEPROM to RAM */
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la $7, _edata
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relocate:
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lw $8, ($5) # $8 = *EEPROM
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addu $5, $5, 4 # EEPROM++
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sw $8, ($6) # *RAM = $8
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addu $6, $6, 4 # RAM++
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bne $6, $7, relocate # copied all the way to edata?
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nop
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la $6, _start_in_ram
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jr $6
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nop
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.end _start
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.globl _start_in_ram
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.ent _start_in_ram
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_start_in_ram:
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nop
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#ifdef __mips_embedded_pic
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PICBASE = .+8
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bal PICBASE
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nop
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move s0,$31
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#endif
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li v0, SR_CU1|SR_PE|SR_FR|SR_KX|SR_SX|SR_UX
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mtc0 v0, C0_SR
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mtc0 zero, C0_CAUSE
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/* Check for FPU presence */
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#ifndef __mips_soft_float
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/* This doesn't work if there is no FPU. We get illegal instruction
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exceptions. */
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li t2,0xAAAA5555
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mtc1 t2,fp0 /* write to FPR 0 */
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mtc1 zero,fp1 /* write to FPR 1 */
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mfc1 t0,fp0
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mfc1 t1,fp1
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nop
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bne t0,t2,1f /* check for match */
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nop
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bne t1,zero,1f /* double check */
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nop
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#ifndef __mips64 /* Clear the FR bit */
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li v0, SR_CU1|SR_PE|SR_KX|SR_SX|SR_UX
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mtc0 v0, C0_SR
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#endif
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j 2f
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nop
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#endif
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1:
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li v0, SR_PE|SR_FR|SR_KX|SR_SX|SR_UX
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mtc0 v0, C0_SR
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2:
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/* Fix high bits, if any, of the PC so that exception handling
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doesn't get confused. */
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LA (v0, 3f)
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jr v0
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nop
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3:
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LA (gp, _gp) # set the global data pointer
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.end _start_in_ram
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/*
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* zero out the bss section.
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*/
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.globl zerobss
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.ent zerobss
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zerobss:
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LA (v0, _fbss)
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LA (v1, _end)
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3:
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sw zero,0(v0)
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bltu v0,v1,3b
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addiu v0,v0,4 # executed in delay slot
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la t0, _stack_init # initialize stack so we
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/* We must subtract 24 bytes for the 3 8 byte arguments to main, in
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case main wants to write them back to the stack. The caller is
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supposed to allocate stack space for parameters in registers in
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the old MIPS ABIs. We must do this even though we aren't passing
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arguments, because main might be declared to have them.
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Some ports need a larger alignment for the stack, so we subtract
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32, which satisifes the stack for the arguments and keeps the
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stack pointer better aligned. */
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subu t0,t0,32
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move sp,t0 # set stack pointer
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.end zerobss
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.globl exit .text
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.globl init
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.ent init
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init:
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move a0,zero # set command line to 0
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jal boot_card # call the program start function
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nop
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/* fall through to the "exit" routine */
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jal _sys_exit /* call libc exit to run the G++ */
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/* destructors */
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move a0,v0 /* pass through the exit code */
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.end init
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/*
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* _sys_exit -- Exit from the application. Normally we cause a user trap
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* to return to the ROM monitor for another run. NOTE: This is
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* the only other routine we provide in the crt0.o object, since
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* it may be tied to the "_start" routine. It also allows
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* executables that contain a complete world to be linked with
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* just the crt0.o object.
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*/
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.globl bsp_reset
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bsp_reset:
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.globl _sys_exit
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.ent _sys_exit
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_sys_exit:
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7:
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#ifdef GCRT0
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jal _mcleanup
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nop
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#endif
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/* break instruction can cope with 0xfffff, but GAS limits the range: */
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break 1023
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nop
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b 7b # but loop back just in-case
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nop
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.end _sys_exit
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/* EOF crt0.S */
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