clear_page.s

Linux内核源代码 为压缩文件 是<<Linux内核>>一书中的源代码

/*
 *
 * Optimized version of the standard clearpage() function
 *
 * Based on comments from ddd. Try not to overflow the write buffer.
 *
 * Inputs:
 *	in0:	address of page
 * 
 * Output:
 * 	none
 *
 * Copyright (C) 1999-2000 Hewlett-Packard Co
 * Copyright (C) 1999 Stephane Eranian <[e-mail]>
 * Copyright (C) 1999-2000 David Mosberger-Tang <[e-mail]>
 */
#include <asm/asmmacro.h>
#include <asm/page.h>

	.text
	.psr abi64
	.psr lsb
	.lsb

GLOBAL_ENTRY(clear_page)
	UNW(.prologue)
	alloc r11=ar.pfs,1,0,0,0
	UNW(.save ar.lc, r16)
	mov r16=ar.lc		// slow

	UNW(.body)

	mov r17=PAGE_SIZE/32-1	// -1 = repeat/until
	;;
	adds r18=16,in0
	mov ar.lc=r17
	;;
1:	stf.spill.nta [in0]=f0,32
	stf.spill.nta [r18]=f0,32
	br.cloop.dptk.few 1b
	;;
	mov ar.lc=r16		// restore lc
	br.ret.sptk.few rp
END(clear_page)