clrbss.s

mips架构的bootloader,99左右的版本 但源代码现在没人更新了

/*************************************************************
 * File: lib/clrbss.s
 * Purpose: Part of C runtime library
 * Author: Phil Bunce ([e-mail])
 * Revision History:
 *	970304	Start of revision history
 *	980107	Added ifdef for GHS
 */

#include <mips.h>

/*
 * Clear the .bss section as required by C language.
 */

	.globl clrbss
	.ent clrbss
clrbss:	# clear the bss area
#ifdef BSO_TASKING
	la	t5,__lc_cp
	beq	t5,zero,3f

4:	lw	t1,0(t5)	# action
	beq	t1,zero,3f

	lw	t2,4(t5)	# dest
	lw	t3,8(t5)	# src
	lw	t4,12(t5)	# len

	sll	t0,t1,31-2
	bgez	t0,1f		# test CP_REL bit

	la	t0,__lc_zp
	addu	t2,t0		# add _zp to dest

1:	sll	t0,t1,31-1
	bgez	t0,2f		# test CP_BSS bit

1:	beq	t4,zero,2f
	sw	zero,(t2)
	addu	t2,4
	subu	t4,4
	b	1b

2:	# next section
	addu	t5,16		# size of entry
	b	4b
3:
#else
#ifdef GHS
	la	v0,__ghsbegin_sbss
	la	v1,__ghsend_bss
1:
	sw	zero,0x0(v0)
	sw	zero,0x4(v0)
	sw	zero,0x8(v0)
	sw	zero,0xc(v0)
	addu	v0,16
	blt	v0,v1,1b
#else
#ifdef EPI
	la	v0,_fsbss
#else
	la	v0,_fbss
#endif
	la	v1,BSS_END
1:
	sw	zero,0x0(v0)
	sw	zero,0x4(v0)
	sw	zero,0x8(v0)
	sw	zero,0xc(v0)
	addu	v0,16
	blt	v0,v1,1b
#endif
#endif
	j	ra
	.end clrbss