1 /* Optimised simple memory fill 2 * 3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells (at) redhat.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public Licence 8 * as published by the Free Software Foundation; either version 9 * 2 of the Licence, or (at your option) any later version. 10 */ 11 #include <asm/cache.h> 12 13 .section .text 14 .balign L1_CACHE_BYTES 15 16 ############################################################################### 17 # 18 # void *memset(void *dst, int c, size_t n) 19 # 20 ############################################################################### 21 .globl memset 22 .type memset,@function 23 memset: 24 movm [d2,d3],(sp) 25 mov d0,(12,sp) 26 mov d1,(16,sp) 27 mov (20,sp),d2 # count 28 mov d0,a0 # dst 29 mov d0,e3 # the return value 30 31 cmp +0,d2 32 beq memset_done # return if zero-length fill 33 34 # see if the region parameters are four-byte aligned 35 or d0,d2,d3 36 and +3,d3 37 bne memset_1 # jump if not 38 39 extbu d1 40 mov_asl d1,d3,8,d1 41 or_asl d1,d3,8,d1 42 or_asl d1,d3,8,d1 43 or d3,d1 44 45 # we want to transfer as much as we can in chunks of 32 bytes 46 cmp +31,d2 47 bls memset_4_remainder # 4-byte aligned remainder 48 49 add -32,d2 50 mov +32,d3 51 52 memset_4_loop: 53 mov d1,(a0+) 54 mov d1,(a0+) 55 mov d1,(a0+) 56 mov d1,(a0+) 57 mov d1,(a0+) 58 mov d1,(a0+) 59 mov d1,(a0+) 60 mov d1,(a0+) 61 62 sub d3,d2 63 bcc memset_4_loop 64 65 add d3,d2 66 beq memset_4_no_remainder 67 68 memset_4_remainder: 69 # cut 4-7 words down to 0-3 70 cmp +16,d2 71 bcs memset_4_three_or_fewer_words 72 mov d1,(a0+) 73 mov d1,(a0+) 74 mov d1,(a0+) 75 mov d1,(a0+) 76 add -16,d2 77 beq memset_4_no_remainder 78 79 # copy the remaining 1, 2 or 3 words 80 memset_4_three_or_fewer_words: 81 cmp +8,d2 82 bcs memset_4_one_word 83 beq memset_4_two_words 84 mov d1,(a0+) 85 memset_4_two_words: 86 mov d1,(a0+) 87 memset_4_one_word: 88 mov d1,(a0+) 89 90 memset_4_no_remainder: 91 # check we set the correct amount 92 # TODO: REMOVE CHECK 93 sub e3,a0,d2 94 mov (20,sp),d1 95 cmp d2,d1 96 beq memset_done 97 break 98 break 99 break 100 101 memset_done: 102 mov e3,a0 103 ret [d2,d3],8 104 105 # handle misaligned copying 106 memset_1: 107 add -1,d2 108 mov +1,d3 109 setlb # setlb requires the next insns 110 # to occupy exactly 4 bytes 111 112 sub d3,d2 113 movbu d1,(a0) 114 inc a0 115 lcc 116 117 mov e3,a0 118 ret [d2,d3],8 119 120 memset_end: 121 .size memset, memset_end-memset 122
