LXR linux/arch/nds32/lib/clear

   1// SPDX-License-Identifier: GPL-2.0
   2// Copyright (C) 2005-2017 Andes Technology Corporation
   3
   4#include <linux/linkage.h>
   5#include <asm/assembler.h>
   6#include <asm/errno.h>
   7
   8/* Prototype: int __arch_clear_user(void *addr, size_t sz)
   9 * Purpose  : clear some user memory
  10 * Params   : addr - user memory address to clear
  11 *          : sz   - number of bytes to clear
  12 * Returns  : number of bytes NOT cleared
  13 */
  14        .text
  15        .align  5
  16ENTRY(__arch_clear_user)
  17        add     $r5, $r0, $r1
  18        beqz    $r1, clear_exit
  19        xor     $p1, $p1, $p1           ! Use $p1=0 to clear mem
  20        srli    $p0, $r1, #2            ! $p0 = number of word to clear
  21        andi    $r1, $r1, #3            ! Bytes less than a word to copy
  22        beqz    $p0, byte_clear         ! Only less than a word to clear
  23word_clear:
  24USER(   smw.bim,$p1, [$r0], $p1)        ! Clear the word
  25        addi    $p0, $p0, #-1           ! Decrease word count
  26        bnez    $p0, word_clear         ! Continue looping to clear all words
  27        beqz    $r1, clear_exit         ! No left bytes to copy
  28byte_clear:
  29USER(   sbi.bi, $p1, [$r0], #1)         ! Clear the byte
  30        addi    $r1, $r1, #-1           ! Decrease byte count
  31        bnez    $r1, byte_clear         ! Continue looping to clear all left bytes
  32clear_exit:
  33        move    $r0, $r1                ! Set return value
  34        ret
  35
  36        .section .fixup,"ax"
  37        .align  0
  389001:
  39        sub     $r0, $r5, $r0           ! Bytes left to copy
  40        ret
  41        .previous
  42ENDPROC(__arch_clear_user)
  43