asmstartup.s

使用广泛的日本著名的开源嵌入式实时操作系统T-Kernel的源码

/*
 *----------------------------------------------------------------------
 *    T-Kernel
 *
 *    Copyright (C) 2004-2006 by Ken Sakamura. All rights reserved.
 *    T-Kernel is distributed under the T-License.
 *----------------------------------------------------------------------
 *
 *    Version:   1.02.02
 *    Released by T-Engine Forum(http://www.t-engine.org) at 2006/8/9.
 *
 *----------------------------------------------------------------------
 */

/*
 *	@(#)asmstartup.S (crttk)
 *
 *	Driver/manager startup 
 */

#include <machine.h>
#include <tk/asm.h>

	.text
	.balign	4
	.globl	_A_startup
	.type	_A_startup, @function
_A_startup:
	bltz	r0, l_noinit		// Initialization sequence is performed only when ac >= 0

	seth	r4, #shigh(__data_org)	// When data area does not need to be moved,
	add3	r4, r4, #low(__data_org)// OS loads
	seth	r5, #shigh(__data_start)
	add3	r5, r5, #low(__data_start)
	beq	r4, r5, l_noinit

	seth	r6, #shigh(_edata)	// initialize data area
	add3	r6, r6, #low(_edata)
	beq	r5, r6, nocopy_data
	addi	r5, #-4
	addi	r6, #-4
  copy_data:
	ld	r7, @r4+
	st	r7, @+r5
	bne	r5, r6, copy_data
  nocopy_data:

	ldi	r7, #0			// clear bss area
	seth	r4, #shigh(__bss_start - 4)
	add3	r4, r4, #low(__bss_start - 4)
	seth	r5, #shigh(_end - 4)
	add3	r5, r5, #low(_end - 4)
	beq	r4, r5, nobss
  clrbss:
	st	r7, @+r4
	bne	r4, r5, clrbss
  nobss:

  l_noinit:
	bra	Csym(_P_startup)