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基于sse2的strstr函數(shù)

Posted on 2008-10-28 21:47 djx_zh 閱讀(2884) 評(píng)論(7) 編輯收藏引用

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昨天實(shí)現(xiàn)了基于int類型的strstr函數(shù)，可以獲得1~2X左右的加速。今天按 lstrstr的流程實(shí)現(xiàn)了基于SSE2的STRSTR函數(shù)。可以得到2~4X左右的加速。

  1 char* lstrstrsse(char* text, char* pattern)
  2 {
  3     __m128i * sseiPtr = (__m128i *) text;
  4     unsigned char * chPtrAligned = (unsigned char*)text;
  5     __m128i sseiWord0 ;//= *sseiPtr ;
  6     __m128i sseiWord1 ;//= *sseiPtr ;
  7     __m128i sseiZero = _mm_set1_epi8(0);
  8     char chara = pattern[0];
  9     char charb = pattern[1];
10     register __m128i byte16a;
11     register __m128i byte16b;
12     char* bytePtr =text;
13     if(pattern ==NULL) return NULL;
14     if(pattern[0] == 0) return NULL;
15     if(pattern[1] == 0) return lstrchr(text,pattern[0]);
16     byte16a = _mm_set1_epi8(chara);
17     byte16b = _mm_set1_epi8(charb);
18 // process the unaligned bytes
19

20 // the aligned bytes
21 alignStart:
22     sseiWord0 = *sseiPtr;
23     sseiWord1 = *(sseiPtr+1);
24     while( haszeroByte(sseiWord0,sseiWord1,sseiZero) ==0)
25     {
26         unsigned int reta ;
27 searcha:
28         reta = hasByteC(sseiWord0,sseiWord1,  byte16a);
29         if(reta!=0 ) {
30             unsigned int retb ;
31 findouta:
32             retb = hasByteC(sseiWord0,sseiWord1,  byte16b);
33 findoutb:
34             if(((reta<<1) & retb)){
35                 // have ab
36                 int i=1;
37                 char * bytePtr0 = (char*) ( sseiPtr );
38                 int j;
39                 //printf("test::%0x,%d\n",reta ,bytePtr0 -text);
40                 bytePtr = (char*) ( sseiPtr );
41                 for(j =0;j<8;j++){
42                     if(reta & 0xff) {
43                         if(bytePtr0[0] == chara){
44                             i =1;
45                             bytePtr = bytePtr0 ;
46                             while((pattern[i] )&&(bytePtr[i] == pattern[i])) i++;
47                             if(pattern[i] == 0) return bytePtr;
48                         }
49                         if(bytePtr0[1] == chara){
50                             i =1;
51                             bytePtr = bytePtr0 + 1;
52                             while((pattern[i] )&&(bytePtr[i] == pattern[i])) i++;
53                             if(pattern[i] == 0) return bytePtr;
54                         }
55                         if(bytePtr0[2] == chara){
56                             i =1;
57                             bytePtr = bytePtr0 + 2;
58                             while((pattern[i] )&&(bytePtr[i] == pattern[i])) i++;
59                             if(pattern[i] == 0) return bytePtr;
60                         }
61                         if(bytePtr0[3] == chara){
62                             i =1;
63                             bytePtr = bytePtr0 + 3;
64                             while((pattern[i] )&&(bytePtr[i] == pattern[i])) i++;
65                             if(pattern[i] == 0) return bytePtr;
66                         }
67                     }
68                     reta = reta >> 4;
69                     bytePtr0 += 4;
70                 }
71             }
72             // search b
73             sseiPtr += 2;
74             sseiWord0 = *sseiPtr;
75             sseiWord1 = *(sseiPtr+1);
76
77             while( haszeroByte(sseiWord0,sseiWord1,sseiZero) ==0){
78                 retb = hasByteC(sseiWord0,sseiWord1,  byte16b);
79                 if(retb !=0){
80                     // findout b
81                     if((*((char*) sseiPtr)) == charb){
82                         //b000
83                         char * bytePtr = ((char*) ( sseiPtr )) -1;
84                         if(bytePtr[0] == chara){
85                             int i=1;
86                             while((pattern[i] )&&(bytePtr[i] == pattern[i])) i++;
87                             if(pattern[i] == 0) return bytePtr;
88                             if(bytePtr[i] == 0) return NULL;
89                         }
90
91                     }
92                     reta = hasByteC(sseiWord0,sseiWord1,  byte16a);
93                     if(reta !=0)
94                         goto findoutb;
95                     else{
96                         goto nextWord;
97                     }
98                 }
99                 sseiPtr += 2;
100                 sseiWord0 = *sseiPtr;
101                 sseiWord1 = *(sseiPtr+1);
102             }
103             // search  from (char*)sseiPtr
104             char * bytePtr = ((char*) ( sseiPtr )) -1;
105             if(bytePtr[0] == chara){
106                 int i=1;
107                 while((pattern[i] )&&(bytePtr[i] == pattern[i])) i++;
108                 if(pattern[i] == 0) return bytePtr;
109             }
110
111             goto prePareForEnd;
112         }
113 nextWord:
114         sseiPtr += 2;
115         sseiWord0 = *sseiPtr;
116         sseiWord1 = *(sseiPtr+1);
117     }
118 prePareForEnd:
119     {
120         unsigned int reta;
121         unsigned int retb;
122         reta =hasByteC(sseiWord0,sseiWord1,  byte16a);
123         retb =hasByteC(sseiWord0,sseiWord1,  byte16b);
124         if(((reta<<1) & retb)){
125             bytePtr = (char*)sseiPtr;
126             while(*bytePtr){
127                 if(*bytePtr == chara) {
128                     int i=1;
129                     while((pattern[i] )&&(bytePtr[i] == pattern[i])) i++;
130                     if(pattern[i] == 0) return bytePtr;
131                     if(bytePtr[i] == 0) return NULL;
132
133                 }
134                 bytePtr++;
135             }
136         }
137     }
138     return NULL;
139 }
140

Feedback

# re: 基于sse2的strstr函數(shù) 回復(fù) 更多評(píng)論

2008-10-30 00:53 by 肥仔

超過了C的strstr?

# re: 基于sse2的strstr函數(shù) 回復(fù) 更多評(píng)論

2008-10-30 09:33 by djxzh

@肥仔
就目前的測(cè)試結(jié)果，是這樣。還沒有測(cè)試最壞情況下會(huì)是什么結(jié)果。

# re: 基于sse2的strstr函數(shù)[未登錄] 回復(fù) 更多評(píng)論

2008-10-30 10:35 by megax

做一個(gè)從后面開始查找的試試？

# re: 基于sse2的strstr函數(shù) 回復(fù) 更多評(píng)論

2008-10-30 10:41 by djxzh

@megax
你是說(shuō)BM之類的算法嗎？那些算法需要對(duì)模式串預(yù)處理。

# re: 基于sse2的strstr函數(shù) 回復(fù) 更多評(píng)論

2008-10-30 10:54 by vczh

用了SSE的指令集就可以同時(shí)計(jì)算一小部分內(nèi)容了。

# re: 基于sse2的strstr函數(shù)[未登錄] 回復(fù) 更多評(píng)論

2008-10-31 12:47 by megax

不是，我說(shuō)的是從一個(gè)字符串后面開始查找想要查找的內(nèi)容。不是說(shuō)具體的算法

# re: 基于sse2的strstr函數(shù) 回復(fù) 更多評(píng)論

2008-11-01 11:02 by 金山詞霸2008

沒想到strstr函數(shù)的設(shè)計(jì)還這么復(fù)雜

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