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/*
 * crt0_cygmon.S -- Minimal startup file for MIPS targets running Cygmon.
 *
 * 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 Cygmon
 * and therefore the hardware will be initialized properly.
 */
 
#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
 
        .comm   __memsize, 12
        .comm   __lstack, STARTUP_STACK_SIZE
        .comm   __stackbase,4
 
        .text
        .align  4
    /*
     * 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
        la              gp, _gp                                 # set the global data pointer, defined in the linker script
        .end    _start
 
    /*
     * zero out the bss section.
     */
        .globl  __memsize
        .globl  get_mem_info .text
        .globl  zerobss
        .ent    zerobss
zerobss:
        la              v0, _fbss                               # These variables are defined in the linker script
        la              v1, _end
 
3:
        sw              zero, 0(v0)
        bltu    v0, v1, 3b
        addiu   v0, v0, 4                               # executed in delay slot
 
    /*
     * Setup a small stack so we can run some C code,
     * and get the usable memory size.
     */
        la              t0, __lstack
        addiu   sp, t0, STARTUP_STACK_SIZE
        la              a0, __memsize
        jal             get_mem_info
        nop
 
        /*
     * 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.
     */
        subu    v0, v0, 32
        move    sp, v0
 
        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 software 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
        # Cygmon expects a break 5
        break   5
        nop
        b               7b                                              # loop back just in-case
        nop
        .end    _exit
 
/* EOF crt0.S */

Line No.	Rev	Author	Line
1	148	jeremybenn	`/*`
2			`* crt0_cygmon.S -- Minimal startup file for MIPS targets running Cygmon.`
3			`*`
4			`* Copyright (c) 1995, 1996, 1997, 2000 Red Hat, Inc.`
5			`*`
6			`* The authors hereby grant permission to use, copy, modify, distribute,`
7			`* and license this software and its documentation for any purpose, provided`
8			`* that existing copyright notices are retained in all copies and that this`
9			`* notice is included verbatim in any distributions. No written agreement,`
10			`* license, or royalty fee is required for any of the authorized uses.`
11			`* Modifications to this software may be copyrighted by their authors`
12			`* and need not follow the licensing terms described here, provided that`
13			`* the new terms are clearly indicated on the first page of each file where`
14			`* they apply.`
15			`*/`
16
17			`/*`
18			`* This file contains the minimal startup code necessary.`
19			`* This will not do any hardware initialization. It is assumed that we are talking to Cygmon`
20			`* and therefore the hardware will be initialized properly.`
21			`*/`
22
23			`#ifdef __mips16`
24			`/* This file contains 32 bit assembly code. */`
25			`.set nomips16`
26			`#endif`
27
28			`#include "regs.S"`
29
30			`/*`
31			`* Set up some room for a stack. We just grab a chunk of memory.`
32			`*/`
33			`#define STACK_SIZE 0x4000`
34			`#define GLOBAL_SIZE 0x2000`
35
36			`#define STARTUP_STACK_SIZE 0x0100`
37
38			`.comm __memsize, 12`
39			`.comm __lstack, STARTUP_STACK_SIZE`
40			`.comm __stackbase,4`
41
42			`.text`
43			`.align 4`
44			`/*`
45			`* Without the following nop, GDB thinks _start is a data variable.`
46			`* This is probably a bug in GDB in handling a symbol that is at the`
47			`* start of the .text section.`
48			`*/`
49			`nop`
50
51			`.globl _start`
52			`.ent _start`
53			`_start:`
54			`.set noreorder`
55			`la gp, _gp # set the global data pointer, defined in the linker script`
56			`.end _start`
57
58			`/*`
59			`* zero out the bss section.`
60			`*/`
61			`.globl __memsize`
62			`.globl get_mem_info .text`
63			`.globl zerobss`
64			`.ent zerobss`
65			`zerobss:`
66			`la v0, _fbss # These variables are defined in the linker script`
67			`la v1, _end`
68
69			`3:`
70			`sw zero, 0(v0)`
71			`bltu v0, v1, 3b`
72			`addiu v0, v0, 4 # executed in delay slot`
73
74			`/*`
75			`* Setup a small stack so we can run some C code,`
76			`* and get the usable memory size.`
77			`*/`
78			`la t0, __lstack`
79			`addiu sp, t0, STARTUP_STACK_SIZE`
80			`la a0, __memsize`
81			`jal get_mem_info`
82			`nop`
83
84			`/*`
85			`* Setup the stack pointer --`
86			`* get_mem_info returns the top of memory, so just use that In`
87			`* addition, we must subtract 24 bytes for the 3 8 byte`
88			`* arguments to main, in case main wants to write them back to`
89			`* the stack. The caller is supposed to allocate stack space`
90			`* for parameters in registers in the old MIPS ABIs. We must`
91			`* do this even though we aren't passing arguments, because`
92			`* main might be declared to have them.`
93			`* Some ports need a larger alignment for the stack, so we`
94			`* subtract 32, which satisifes the stack for the arguments and`
95			`* keeps the stack pointer better aligned.`
96			`*/`
97			`subu v0, v0, 32`
98			`move sp, v0`
99
100			`sw sp, __stackbase # keep this for future ref`
101			`.end zerobss`
102
103			`/*`
104			`* initialize target specific stuff. Only execute these`
105			`* functions it they exist.`
106			`*/`
107			`.globl hardware_init_hook .text`
108			`.globl software_init_hook .text`
109			`.globl __do_global_dtors .text`
110			`.globl atexit .text`
111			`.globl exit .text`
112			`.globl init`
113			`.ent init`
114			`init:`
115			`la t9, hardware_init_hook # init the hardware if needed`
116			`beq t9, zero, 6f`
117			`nop`
118			`jal t9`
119			`nop`
120			`6:`
121			`la t9, software_init_hook # init the software if needed`
122			`beq t9, zero, 7f`
123			`nop`
124			`jal t9`
125			`nop`
126			`7:`
127			`la a0, __do_global_dtors`
128			`jal atexit`
129			`nop`
130
131			`#ifdef GCRT0`
132			`.globl _ftext`
133			`.globl _extext`
134			`la a0, _ftext`
135			`la a1, _etext`
136			`jal monstartup`
137			`nop`
138			`#endif`
139
140			`move a0,zero # set argc to 0`
141			`jal main # call the program start function`
142			`nop`
143
144			`# fall through to the "exit" routine`
145			`jal exit # call libc exit to run the G++`
146			`# destructors`
147			`move a0, v0 # pass through the exit code`
148			`.end init`
149
150			`/*`
151			`* _exit -- Exit from the application. Normally we cause a user trap`
152			`* to return to the ROM monitor for another run. NOTE: This is`
153			`* the only other routine we provide in the crt0.o object, since`
154			`* it may be tied to the "_start" routine. It also allows`
155			`* executables that contain a complete world to be linked with`
156			`* just the crt0.o object.`
157			`*/`
158			`.globl _exit`
159			`.ent _exit`
160			`_exit:`
161			`7:`
162			`#ifdef GCRT0`
163			`jal _mcleanup`
164			`nop`
165			`#endif`
166			`# Cygmon expects a break 5`
167			`break 5`
168			`nop`
169			`b 7b # loop back just in-case`
170			`nop`
171			`.end _exit`
172
173			`/* EOF crt0.S */`

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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [libgloss/] [mips/] [crt0_cygmon.S] - Blame information for rev 455