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@@ -1,322 +1,322 b'' | |||||
1 | /* |
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1 | /* | |
2 | bdiff.c - efficient binary diff extension for Mercurial |
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2 | bdiff.c - efficient binary diff extension for Mercurial | |
3 |
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3 | |||
4 | Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> |
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4 | Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> | |
5 |
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5 | |||
6 | This software may be used and distributed according to the terms of |
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6 | This software may be used and distributed according to the terms of | |
7 | the GNU General Public License, incorporated herein by reference. |
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7 | the GNU General Public License, incorporated herein by reference. | |
8 |
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8 | |||
9 | Based roughly on Python difflib |
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9 | Based roughly on Python difflib | |
10 | */ |
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10 | */ | |
11 |
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11 | |||
12 | #include <limits.h> |
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12 | #include <limits.h> | |
13 | #include <stdlib.h> |
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13 | #include <stdlib.h> | |
14 | #include <string.h> |
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14 | #include <string.h> | |
15 |
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15 | |||
16 | #include "bdiff.h" |
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16 | #include "bdiff.h" | |
17 | #include "bitmanipulation.h" |
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17 | #include "bitmanipulation.h" | |
18 | #include "compat.h" |
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18 | #include "compat.h" | |
19 |
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19 | |||
20 | /* Hash implementation from diffutils */ |
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20 | /* Hash implementation from diffutils */ | |
21 | #define ROL(v, n) ((v) << (n) | (v) >> (sizeof(v) * CHAR_BIT - (n))) |
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21 | #define ROL(v, n) ((v) << (n) | (v) >> (sizeof(v) * CHAR_BIT - (n))) | |
22 | #define HASH(h, c) ((c) + ROL(h, 7)) |
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22 | #define HASH(h, c) ((c) + ROL(h, 7)) | |
23 |
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23 | |||
24 | struct pos { |
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24 | struct pos { | |
25 | int pos, len; |
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25 | int pos, len; | |
26 | }; |
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26 | }; | |
27 |
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27 | |||
28 | int bdiff_splitlines(const char *a, ssize_t len, struct bdiff_line **lr) |
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28 | int bdiff_splitlines(const char *a, ssize_t len, struct bdiff_line **lr) | |
29 | { |
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29 | { | |
30 | unsigned hash; |
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30 | unsigned hash; | |
31 | int i; |
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31 | int i; | |
32 | const char *p, *b = a; |
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32 | const char *p, *b = a; | |
33 | const char *const plast = a + len - 1; |
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33 | const char *const plast = a + len - 1; | |
34 | struct bdiff_line *l; |
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34 | struct bdiff_line *l; | |
35 |
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35 | |||
36 | /* count the lines */ |
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36 | /* count the lines */ | |
37 | i = 1; /* extra line for sentinel */ |
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37 | i = 1; /* extra line for sentinel */ | |
38 | for (p = a; p < plast; p++) |
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38 | for (p = a; p < plast; p++) | |
39 | if (*p == '\n') |
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39 | if (*p == '\n') | |
40 | i++; |
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40 | i++; | |
41 | if (p == plast) |
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41 | if (p == plast) | |
42 | i++; |
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42 | i++; | |
43 |
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43 | |||
44 | *lr = l = (struct bdiff_line *)malloc(sizeof(struct bdiff_line) * i); |
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44 | *lr = l = (struct bdiff_line *)malloc(sizeof(struct bdiff_line) * i); | |
45 | if (!l) |
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45 | if (!l) | |
46 | return -1; |
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46 | return -1; | |
47 |
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47 | |||
48 | /* build the line array and calculate hashes */ |
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48 | /* build the line array and calculate hashes */ | |
49 | hash = 0; |
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49 | hash = 0; | |
50 | for (p = a; p < plast; p++) { |
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50 | for (p = a; p < plast; p++) { | |
51 | hash = HASH(hash, *p); |
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51 | hash = HASH(hash, *p); | |
52 |
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52 | |||
53 | if (*p == '\n') { |
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53 | if (*p == '\n') { | |
54 | l->hash = hash; |
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54 | l->hash = hash; | |
55 | hash = 0; |
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55 | hash = 0; | |
56 | l->len = p - b + 1; |
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56 | l->len = p - b + 1; | |
57 | l->l = b; |
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57 | l->l = b; | |
58 | l->n = INT_MAX; |
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58 | l->n = INT_MAX; | |
59 | l++; |
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59 | l++; | |
60 | b = p + 1; |
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60 | b = p + 1; | |
61 | } |
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61 | } | |
62 | } |
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62 | } | |
63 |
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63 | |||
64 | if (p == plast) { |
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64 | if (p == plast) { | |
65 | hash = HASH(hash, *p); |
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65 | hash = HASH(hash, *p); | |
66 | l->hash = hash; |
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66 | l->hash = hash; | |
67 | l->len = p - b + 1; |
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67 | l->len = p - b + 1; | |
68 | l->l = b; |
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68 | l->l = b; | |
69 | l->n = INT_MAX; |
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69 | l->n = INT_MAX; | |
70 | l++; |
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70 | l++; | |
71 | } |
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71 | } | |
72 |
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72 | |||
73 | /* set up a sentinel */ |
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73 | /* set up a sentinel */ | |
74 | l->hash = 0; |
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74 | l->hash = 0; | |
75 | l->len = 0; |
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75 | l->len = 0; | |
76 | l->l = a + len; |
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76 | l->l = a + len; | |
77 | return i - 1; |
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77 | return i - 1; | |
78 | } |
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78 | } | |
79 |
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79 | |||
80 | static inline int cmp(struct bdiff_line *a, struct bdiff_line *b) |
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80 | static inline int cmp(struct bdiff_line *a, struct bdiff_line *b) | |
81 | { |
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81 | { | |
82 | return a->hash != b->hash || a->len != b->len || |
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82 | return a->hash != b->hash || a->len != b->len || | |
83 | memcmp(a->l, b->l, a->len); |
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83 | memcmp(a->l, b->l, a->len); | |
84 | } |
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84 | } | |
85 |
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85 | |||
86 | static int equatelines(struct bdiff_line *a, int an, struct bdiff_line *b, |
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86 | static int equatelines(struct bdiff_line *a, int an, struct bdiff_line *b, | |
87 | int bn) |
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87 | int bn) | |
88 | { |
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88 | { | |
89 | int i, j, buckets = 1, t, scale; |
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89 | int i, j, buckets = 1, t, scale; | |
90 | struct pos *h = NULL; |
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90 | struct pos *h = NULL; | |
91 |
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91 | |||
92 | /* build a hash table of the next highest power of 2 */ |
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92 | /* build a hash table of the next highest power of 2 */ | |
93 | while (buckets < bn + 1) |
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93 | while (buckets < bn + 1) | |
94 | buckets *= 2; |
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94 | buckets *= 2; | |
95 |
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95 | |||
96 | /* try to allocate a large hash table to avoid collisions */ |
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96 | /* try to allocate a large hash table to avoid collisions */ | |
97 | for (scale = 4; scale; scale /= 2) { |
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97 | for (scale = 4; scale; scale /= 2) { | |
98 | h = (struct pos *)malloc(scale * buckets * sizeof(struct pos)); |
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98 | h = (struct pos *)malloc(scale * buckets * sizeof(struct pos)); | |
99 | if (h) |
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99 | if (h) | |
100 | break; |
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100 | break; | |
101 | } |
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101 | } | |
102 |
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102 | |||
103 | if (!h) |
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103 | if (!h) | |
104 | return 0; |
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104 | return 0; | |
105 |
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105 | |||
106 | buckets = buckets * scale - 1; |
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106 | buckets = buckets * scale - 1; | |
107 |
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107 | |||
108 | /* clear the hash table */ |
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108 | /* clear the hash table */ | |
109 | for (i = 0; i <= buckets; i++) { |
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109 | for (i = 0; i <= buckets; i++) { | |
110 | h[i].pos = -1; |
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110 | h[i].pos = -1; | |
111 | h[i].len = 0; |
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111 | h[i].len = 0; | |
112 | } |
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112 | } | |
113 |
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113 | |||
114 | /* add lines to the hash table chains */ |
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114 | /* add lines to the hash table chains */ | |
115 | for (i = 0; i < bn; i++) { |
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115 | for (i = 0; i < bn; i++) { | |
116 | /* find the equivalence class */ |
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116 | /* find the equivalence class */ | |
117 | for (j = b[i].hash & buckets; h[j].pos != -1; |
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117 | for (j = b[i].hash & buckets; h[j].pos != -1; | |
118 | j = (j + 1) & buckets) |
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118 | j = (j + 1) & buckets) | |
119 | if (!cmp(b + i, b + h[j].pos)) |
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119 | if (!cmp(b + i, b + h[j].pos)) | |
120 | break; |
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120 | break; | |
121 |
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121 | |||
122 | /* add to the head of the equivalence class */ |
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122 | /* add to the head of the equivalence class */ | |
123 | b[i].n = h[j].pos; |
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123 | b[i].n = h[j].pos; | |
124 | b[i].e = j; |
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124 | b[i].e = j; | |
125 | h[j].pos = i; |
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125 | h[j].pos = i; | |
126 | h[j].len++; /* keep track of popularity */ |
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126 | h[j].len++; /* keep track of popularity */ | |
127 | } |
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127 | } | |
128 |
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128 | |||
129 | /* compute popularity threshold */ |
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129 | /* compute popularity threshold */ | |
130 | t = (bn >= 31000) ? bn / 1000 : 1000000 / (bn + 1); |
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130 | t = (bn >= 31000) ? bn / 1000 : 1000000 / (bn + 1); | |
131 |
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131 | |||
132 | /* match items in a to their equivalence class in b */ |
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132 | /* match items in a to their equivalence class in b */ | |
133 | for (i = 0; i < an; i++) { |
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133 | for (i = 0; i < an; i++) { | |
134 | /* find the equivalence class */ |
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134 | /* find the equivalence class */ | |
135 | for (j = a[i].hash & buckets; h[j].pos != -1; |
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135 | for (j = a[i].hash & buckets; h[j].pos != -1; | |
136 | j = (j + 1) & buckets) |
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136 | j = (j + 1) & buckets) | |
137 | if (!cmp(a + i, b + h[j].pos)) |
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137 | if (!cmp(a + i, b + h[j].pos)) | |
138 | break; |
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138 | break; | |
139 |
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139 | |||
140 | a[i].e = j; /* use equivalence class for quick compare */ |
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140 | a[i].e = j; /* use equivalence class for quick compare */ | |
141 | if (h[j].len <= t) |
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141 | if (h[j].len <= t) | |
142 | a[i].n = h[j].pos; /* point to head of match list */ |
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142 | a[i].n = h[j].pos; /* point to head of match list */ | |
143 | else |
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143 | else | |
144 | a[i].n = -1; /* too popular */ |
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144 | a[i].n = -1; /* too popular */ | |
145 | } |
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145 | } | |
146 |
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146 | |||
147 | /* discard hash tables */ |
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147 | /* discard hash tables */ | |
148 | free(h); |
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148 | free(h); | |
149 | return 1; |
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149 | return 1; | |
150 | } |
|
150 | } | |
151 |
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151 | |||
152 | static int longest_match(struct bdiff_line *a, struct bdiff_line *b, |
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152 | static int longest_match(struct bdiff_line *a, struct bdiff_line *b, | |
153 | struct pos *pos, |
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153 | struct pos *pos, int a1, int a2, int b1, int b2, | |
154 | int a1, int a2, int b1, int b2, int *omi, int *omj) |
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154 | int *omi, int *omj) | |
155 | { |
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155 | { | |
156 | int mi = a1, mj = b1, mk = 0, i, j, k, half, bhalf; |
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156 | int mi = a1, mj = b1, mk = 0, i, j, k, half, bhalf; | |
157 |
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157 | |||
158 | /* window our search on large regions to better bound |
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158 | /* window our search on large regions to better bound | |
159 | worst-case performance. by choosing a window at the end, we |
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159 | worst-case performance. by choosing a window at the end, we | |
160 | reduce skipping overhead on the b chains. */ |
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160 | reduce skipping overhead on the b chains. */ | |
161 | if (a2 - a1 > 30000) |
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161 | if (a2 - a1 > 30000) | |
162 | a1 = a2 - 30000; |
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162 | a1 = a2 - 30000; | |
163 |
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163 | |||
164 | half = (a1 + a2 - 1) / 2; |
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164 | half = (a1 + a2 - 1) / 2; | |
165 | bhalf = (b1 + b2 - 1) / 2; |
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165 | bhalf = (b1 + b2 - 1) / 2; | |
166 |
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166 | |||
167 | for (i = a1; i < a2; i++) { |
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167 | for (i = a1; i < a2; i++) { | |
168 | /* skip all lines in b after the current block */ |
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168 | /* skip all lines in b after the current block */ | |
169 | for (j = a[i].n; j >= b2; j = b[j].n) |
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169 | for (j = a[i].n; j >= b2; j = b[j].n) | |
170 | ; |
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170 | ; | |
171 |
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171 | |||
172 | /* loop through all lines match a[i] in b */ |
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172 | /* loop through all lines match a[i] in b */ | |
173 | for (; j >= b1; j = b[j].n) { |
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173 | for (; j >= b1; j = b[j].n) { | |
174 | /* does this extend an earlier match? */ |
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174 | /* does this extend an earlier match? */ | |
175 | for (k = 1; j - k >= b1 && i - k >= a1; k++) { |
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175 | for (k = 1; j - k >= b1 && i - k >= a1; k++) { | |
176 | /* reached an earlier match? */ |
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176 | /* reached an earlier match? */ | |
177 | if (pos[j - k].pos == i - k) { |
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177 | if (pos[j - k].pos == i - k) { | |
178 | k += pos[j - k].len; |
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178 | k += pos[j - k].len; | |
179 | break; |
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179 | break; | |
180 | } |
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180 | } | |
181 | /* previous line mismatch? */ |
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181 | /* previous line mismatch? */ | |
182 | if (a[i - k].e != b[j - k].e) |
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182 | if (a[i - k].e != b[j - k].e) | |
183 | break; |
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183 | break; | |
184 | } |
|
184 | } | |
185 |
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185 | |||
186 | pos[j].pos = i; |
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186 | pos[j].pos = i; | |
187 | pos[j].len = k; |
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187 | pos[j].len = k; | |
188 |
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188 | |||
189 | /* best match so far? we prefer matches closer |
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189 | /* best match so far? we prefer matches closer | |
190 | to the middle to balance recursion */ |
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190 | to the middle to balance recursion */ | |
191 | if (k > mk) { |
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191 | if (k > mk) { | |
192 | /* a longer match */ |
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192 | /* a longer match */ | |
193 | mi = i; |
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193 | mi = i; | |
194 | mj = j; |
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194 | mj = j; | |
195 | mk = k; |
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195 | mk = k; | |
196 | } else if (k == mk) { |
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196 | } else if (k == mk) { | |
197 | if (i > mi && i <= half && j > b1) { |
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197 | if (i > mi && i <= half && j > b1) { | |
198 | /* same match but closer to half */ |
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198 | /* same match but closer to half */ | |
199 | mi = i; |
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199 | mi = i; | |
200 | mj = j; |
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200 | mj = j; | |
201 | } else if (i == mi && (mj > bhalf || i == a1)) { |
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201 | } else if (i == mi && (mj > bhalf || i == a1)) { | |
202 | /* same i but best earlier j */ |
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202 | /* same i but best earlier j */ | |
203 | mj = j; |
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203 | mj = j; | |
204 | } |
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204 | } | |
205 | } |
|
205 | } | |
206 | } |
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206 | } | |
207 | } |
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207 | } | |
208 |
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208 | |||
209 | if (mk) { |
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209 | if (mk) { | |
210 | mi = mi - mk + 1; |
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210 | mi = mi - mk + 1; | |
211 | mj = mj - mk + 1; |
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211 | mj = mj - mk + 1; | |
212 | } |
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212 | } | |
213 |
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213 | |||
214 | /* expand match to include subsequent popular lines */ |
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214 | /* expand match to include subsequent popular lines */ | |
215 | while (mi + mk < a2 && mj + mk < b2 && a[mi + mk].e == b[mj + mk].e) |
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215 | while (mi + mk < a2 && mj + mk < b2 && a[mi + mk].e == b[mj + mk].e) | |
216 | mk++; |
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216 | mk++; | |
217 |
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217 | |||
218 | *omi = mi; |
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218 | *omi = mi; | |
219 | *omj = mj; |
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219 | *omj = mj; | |
220 |
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220 | |||
221 | return mk; |
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221 | return mk; | |
222 | } |
|
222 | } | |
223 |
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223 | |||
224 | static struct bdiff_hunk *recurse(struct bdiff_line *a, struct bdiff_line *b, |
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224 | static struct bdiff_hunk *recurse(struct bdiff_line *a, struct bdiff_line *b, | |
225 | struct pos *pos, |
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225 | struct pos *pos, int a1, int a2, int b1, | |
226 |
|
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226 | int b2, struct bdiff_hunk *l) | |
227 | { |
|
227 | { | |
228 | int i, j, k; |
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228 | int i, j, k; | |
229 |
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229 | |||
230 | while (1) { |
|
230 | while (1) { | |
231 | /* find the longest match in this chunk */ |
|
231 | /* find the longest match in this chunk */ | |
232 | k = longest_match(a, b, pos, a1, a2, b1, b2, &i, &j); |
|
232 | k = longest_match(a, b, pos, a1, a2, b1, b2, &i, &j); | |
233 | if (!k) |
|
233 | if (!k) | |
234 | return l; |
|
234 | return l; | |
235 |
|
235 | |||
236 | /* and recurse on the remaining chunks on either side */ |
|
236 | /* and recurse on the remaining chunks on either side */ | |
237 | l = recurse(a, b, pos, a1, i, b1, j, l); |
|
237 | l = recurse(a, b, pos, a1, i, b1, j, l); | |
238 | if (!l) |
|
238 | if (!l) | |
239 | return NULL; |
|
239 | return NULL; | |
240 |
|
240 | |||
241 | l->next = |
|
241 | l->next = | |
242 | (struct bdiff_hunk *)malloc(sizeof(struct bdiff_hunk)); |
|
242 | (struct bdiff_hunk *)malloc(sizeof(struct bdiff_hunk)); | |
243 | if (!l->next) |
|
243 | if (!l->next) | |
244 | return NULL; |
|
244 | return NULL; | |
245 |
|
245 | |||
246 | l = l->next; |
|
246 | l = l->next; | |
247 | l->a1 = i; |
|
247 | l->a1 = i; | |
248 | l->a2 = i + k; |
|
248 | l->a2 = i + k; | |
249 | l->b1 = j; |
|
249 | l->b1 = j; | |
250 | l->b2 = j + k; |
|
250 | l->b2 = j + k; | |
251 | l->next = NULL; |
|
251 | l->next = NULL; | |
252 |
|
252 | |||
253 | /* tail-recursion didn't happen, so do equivalent iteration */ |
|
253 | /* tail-recursion didn't happen, so do equivalent iteration */ | |
254 | a1 = i + k; |
|
254 | a1 = i + k; | |
255 | b1 = j + k; |
|
255 | b1 = j + k; | |
256 | } |
|
256 | } | |
257 | } |
|
257 | } | |
258 |
|
258 | |||
259 | int bdiff_diff(struct bdiff_line *a, int an, struct bdiff_line *b, |
|
259 | int bdiff_diff(struct bdiff_line *a, int an, struct bdiff_line *b, int bn, | |
260 |
|
|
260 | struct bdiff_hunk *base) | |
261 | { |
|
261 | { | |
262 | struct bdiff_hunk *curr; |
|
262 | struct bdiff_hunk *curr; | |
263 | struct pos *pos; |
|
263 | struct pos *pos; | |
264 | int t, count = 0; |
|
264 | int t, count = 0; | |
265 |
|
265 | |||
266 | /* allocate and fill arrays */ |
|
266 | /* allocate and fill arrays */ | |
267 | t = equatelines(a, an, b, bn); |
|
267 | t = equatelines(a, an, b, bn); | |
268 | pos = (struct pos *)calloc(bn ? bn : 1, sizeof(struct pos)); |
|
268 | pos = (struct pos *)calloc(bn ? bn : 1, sizeof(struct pos)); | |
269 |
|
269 | |||
270 | if (pos && t) { |
|
270 | if (pos && t) { | |
271 | /* generate the matching block list */ |
|
271 | /* generate the matching block list */ | |
272 |
|
272 | |||
273 | curr = recurse(a, b, pos, 0, an, 0, bn, base); |
|
273 | curr = recurse(a, b, pos, 0, an, 0, bn, base); | |
274 | if (!curr) |
|
274 | if (!curr) | |
275 | return -1; |
|
275 | return -1; | |
276 |
|
276 | |||
277 | /* sentinel end hunk */ |
|
277 | /* sentinel end hunk */ | |
278 | curr->next = |
|
278 | curr->next = | |
279 | (struct bdiff_hunk *)malloc(sizeof(struct bdiff_hunk)); |
|
279 | (struct bdiff_hunk *)malloc(sizeof(struct bdiff_hunk)); | |
280 | if (!curr->next) |
|
280 | if (!curr->next) | |
281 | return -1; |
|
281 | return -1; | |
282 | curr = curr->next; |
|
282 | curr = curr->next; | |
283 | curr->a1 = curr->a2 = an; |
|
283 | curr->a1 = curr->a2 = an; | |
284 | curr->b1 = curr->b2 = bn; |
|
284 | curr->b1 = curr->b2 = bn; | |
285 | curr->next = NULL; |
|
285 | curr->next = NULL; | |
286 | } |
|
286 | } | |
287 |
|
287 | |||
288 | free(pos); |
|
288 | free(pos); | |
289 |
|
289 | |||
290 | /* normalize the hunk list, try to push each hunk towards the end */ |
|
290 | /* normalize the hunk list, try to push each hunk towards the end */ | |
291 | for (curr = base->next; curr; curr = curr->next) { |
|
291 | for (curr = base->next; curr; curr = curr->next) { | |
292 | struct bdiff_hunk *next = curr->next; |
|
292 | struct bdiff_hunk *next = curr->next; | |
293 |
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293 | |||
294 | if (!next) |
|
294 | if (!next) | |
295 | break; |
|
295 | break; | |
296 |
|
296 | |||
297 | if (curr->a2 == next->a1 || curr->b2 == next->b1) |
|
297 | if (curr->a2 == next->a1 || curr->b2 == next->b1) | |
298 | while (curr->a2 < an && curr->b2 < bn && |
|
298 | while (curr->a2 < an && curr->b2 < bn && | |
299 | next->a1 < next->a2 && next->b1 < next->b2 && |
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299 | next->a1 < next->a2 && next->b1 < next->b2 && | |
300 | !cmp(a + curr->a2, b + curr->b2)) { |
|
300 | !cmp(a + curr->a2, b + curr->b2)) { | |
301 | curr->a2++; |
|
301 | curr->a2++; | |
302 | next->a1++; |
|
302 | next->a1++; | |
303 | curr->b2++; |
|
303 | curr->b2++; | |
304 | next->b1++; |
|
304 | next->b1++; | |
305 | } |
|
305 | } | |
306 | } |
|
306 | } | |
307 |
|
307 | |||
308 | for (curr = base->next; curr; curr = curr->next) |
|
308 | for (curr = base->next; curr; curr = curr->next) | |
309 | count++; |
|
309 | count++; | |
310 | return count; |
|
310 | return count; | |
311 | } |
|
311 | } | |
312 |
|
312 | |||
313 | void bdiff_freehunks(struct bdiff_hunk *l) |
|
313 | void bdiff_freehunks(struct bdiff_hunk *l) | |
314 | { |
|
314 | { | |
315 | struct bdiff_hunk *n; |
|
315 | struct bdiff_hunk *n; | |
316 | for (; l; l = n) { |
|
316 | for (; l; l = n) { | |
317 | n = l->next; |
|
317 | n = l->next; | |
318 | free(l); |
|
318 | free(l); | |
319 | } |
|
319 | } | |
320 | } |
|
320 | } | |
321 |
|
321 | |||
322 |
|
322 |
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