[newlib-cygwin.git] / libgloss / mips / crt0_cygmon.S

/*
 * 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 */
Commit	Line	Data
2d210c7f JJ	1	/*
	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 */