1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
|
/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA */
/*
get_ptr_compare(len) returns a pointer to a optimal byte-compare function
for a array of stringpointer where all strings have size len.
The bytes are compare as unsigned chars.
*/
#include "mysys_priv.h"
static int ptr_compare(uint *compare_length, uchar **a, uchar **b);
static int ptr_compare_0(uint *compare_length, uchar **a, uchar **b);
static int ptr_compare_1(uint *compare_length, uchar **a, uchar **b);
static int ptr_compare_2(uint *compare_length, uchar **a, uchar **b);
static int ptr_compare_3(uint *compare_length, uchar **a, uchar **b);
/* Get a pointer to a optimal byte-compare function for a given size */
qsort2_cmp get_ptr_compare (uint size)
{
if (size < 4)
return (qsort2_cmp) ptr_compare;
switch (size & 3) {
case 0: return (qsort2_cmp) ptr_compare_0;
case 1: return (qsort2_cmp) ptr_compare_1;
case 2: return (qsort2_cmp) ptr_compare_2;
case 3: return (qsort2_cmp) ptr_compare_3;
}
return 0; /* Impossible */
}
/*
Compare to keys to see witch is smaller.
Loop unrolled to make it quick !!
*/
#define cmp(N) if (first[N] != last[N]) return (int) first[N] - (int) last[N]
static int ptr_compare(uint *compare_length, uchar **a, uchar **b)
{
reg3 int length= *compare_length;
reg1 uchar *first,*last;
first= *a; last= *b;
while (--length)
{
if (*first++ != *last++)
return (int) first[-1] - (int) last[-1];
}
return (int) first[0] - (int) last[0];
}
static int ptr_compare_0(uint *compare_length,uchar **a, uchar **b)
{
reg3 int length= *compare_length;
reg1 uchar *first,*last;
first= *a; last= *b;
loop:
cmp(0);
cmp(1);
cmp(2);
cmp(3);
if ((length-=4))
{
first+=4;
last+=4;
goto loop;
}
return (0);
}
static int ptr_compare_1(uint *compare_length,uchar **a, uchar **b)
{
reg3 int length= *compare_length-1;
reg1 uchar *first,*last;
first= *a+1; last= *b+1;
cmp(-1);
loop:
cmp(0);
cmp(1);
cmp(2);
cmp(3);
if ((length-=4))
{
first+=4;
last+=4;
goto loop;
}
return (0);
}
static int ptr_compare_2(uint *compare_length,uchar **a, uchar **b)
{
reg3 int length= *compare_length-2;
reg1 uchar *first,*last;
first= *a +2 ; last= *b +2;
cmp(-2);
cmp(-1);
loop:
cmp(0);
cmp(1);
cmp(2);
cmp(3);
if ((length-=4))
{
first+=4;
last+=4;
goto loop;
}
return (0);
}
static int ptr_compare_3(uint *compare_length,uchar **a, uchar **b)
{
reg3 int length= *compare_length-3;
reg1 uchar *first,*last;
first= *a +3 ; last= *b +3;
cmp(-3);
cmp(-2);
cmp(-1);
loop:
cmp(0);
cmp(1);
cmp(2);
cmp(3);
if ((length-=4))
{
first+=4;
last+=4;
goto loop;
}
return (0);
}
|
