174 lines
4.3 KiB
ArmAsm
174 lines
4.3 KiB
ArmAsm
/*
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* crt0_cygmon.S -- Minimal startup file for MIPS targets running Cygmon.
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*
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* Copyright (c) 1995, 1996, 1997, 2000 Red Hat, Inc.
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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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/*
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* This file contains the minimal startup code necessary.
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* This will not do any hardware initialization. It is assumed that we are talking to Cygmon
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* and therefore the hardware will be initialized properly.
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*/
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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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#include "regs.S"
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/*
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* Set up some room for a stack. We just grab a chunk of memory.
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*/
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#define STACK_SIZE 0x4000
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#define GLOBAL_SIZE 0x2000
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#define STARTUP_STACK_SIZE 0x0100
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.comm __memsize, 12
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.comm __lstack, STARTUP_STACK_SIZE
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.comm __stackbase,4
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.text
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.align 4
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/*
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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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la gp, _gp # set the global data pointer, defined in the linker script
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.end _start
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/*
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* zero out the bss section.
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*/
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.globl __memsize
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.globl get_mem_info .text
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.globl zerobss
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.ent zerobss
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zerobss:
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la v0, _fbss # These variables are defined in the linker script
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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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/*
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* Setup a small stack so we can run some C code,
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* and get the usable memory size.
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*/
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la t0, __lstack
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addiu sp, t0, STARTUP_STACK_SIZE
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la a0, __memsize
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jal get_mem_info
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nop
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/*
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* Setup the stack pointer --
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* get_mem_info returns the top of memory, so just use that In
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* addition, we must subtract 24 bytes for the 3 8 byte
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* arguments to main, in case main wants to write them back to
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* the stack. The caller is supposed to allocate stack space
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* for parameters in registers in the old MIPS ABIs. We must
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* do this even though we aren't passing arguments, because
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* main might be declared to have them.
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* Some ports need a larger alignment for the stack, so we
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* subtract 32, which satisifes the stack for the arguments and
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* keeps the stack pointer better aligned.
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*/
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subu v0, v0, 32
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move sp, v0
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sw sp, __stackbase # keep this for future ref
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.end zerobss
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/*
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* initialize target specific stuff. Only execute these
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* functions it they exist.
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*/
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.globl hardware_init_hook .text
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.globl software_init_hook .text
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.globl __do_global_dtors .text
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.globl atexit .text
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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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la t9, hardware_init_hook # init the hardware if needed
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beq t9, zero, 6f
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nop
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jal t9
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nop
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6:
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la t9, software_init_hook # init the software if needed
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beq t9, zero, 7f
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nop
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jal t9
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nop
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7:
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la a0, __do_global_dtors
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jal atexit
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nop
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#ifdef GCRT0
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.globl _ftext
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.globl _extext
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la a0, _ftext
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la a1, _etext
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jal monstartup
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nop
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#endif
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move a0,zero # set argc to 0
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jal main # 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 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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* _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 _exit
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.ent _exit
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_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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# Cygmon expects a break 5
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break 5
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nop
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b 7b # loop back just in-case
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nop
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.end _exit
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/* EOF crt0.S */
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