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Rev | Author | Line No. | Line |
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1905 | serge | 1 | /* |
2 | index: frame index data structure and functions |
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3 | |||
4 | copyright 2007-8 by the mpg123 project - free software under the terms of the LGPL 2.1 |
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5 | see COPYING and AUTHORS files in distribution or http://mpg123.org |
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6 | initially written by Thomas Orgis |
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7 | */ |
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8 | |||
9 | #include "index.h" |
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10 | #include "debug.h" |
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11 | |||
12 | /* The next expected frame offset, one step ahead. */ |
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13 | static off_t fi_next(struct frame_index *fi) |
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14 | { |
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15 | return (off_t)fi->fill*fi->step; |
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16 | } |
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17 | |||
18 | /* Shrink down the used index to the half. |
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19 | Be careful with size = 1 ... there's no shrinking possible there. */ |
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20 | static void fi_shrink(struct frame_index *fi) |
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21 | { |
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22 | if(fi->fill < 2) return; /* Won't shrink below 1. */ |
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23 | else |
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24 | { /* Double the step, half the fill. Should work as well for fill%2 = 1 */ |
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25 | size_t c; |
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26 | debug2("shrink index with fill %lu and step %lu", (unsigned long)fi->fill, (unsigned long)fi->step); |
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27 | fi->step *= 2; |
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28 | fi->fill /= 2; |
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29 | /* Move the data down. */ |
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30 | for(c = 0; c < fi->fill; ++c) |
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31 | fi->data[c] = fi->data[2*c]; |
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32 | } |
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33 | |||
34 | fi->next = fi_next(fi); |
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35 | } |
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36 | |||
37 | void fi_init(struct frame_index *fi) |
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38 | { |
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39 | fi->data = NULL; |
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40 | fi->step = 1; |
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41 | fi->fill = 0; |
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42 | fi->size = 0; |
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43 | fi->grow_size = 0; |
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44 | fi->next = fi_next(fi); |
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45 | } |
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46 | |||
47 | void fi_exit(struct frame_index *fi) |
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48 | { |
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49 | debug2("fi_exit: %p and %lu", (void*)fi->data, (unsigned long)fi->size); |
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50 | if(fi->size && fi->data != NULL) free(fi->data); |
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51 | |||
52 | fi_init(fi); /* Be prepared for further fun, still. */ |
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53 | } |
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54 | |||
55 | int fi_resize(struct frame_index *fi, size_t newsize) |
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56 | { |
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57 | off_t *newdata = NULL; |
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58 | if(newsize == fi->size) return 0; |
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59 | |||
60 | if(newsize > 0 && newsize < fi->size) |
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61 | { /* When we reduce buffer size a bit, shrink stuff. */ |
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62 | while(fi->fill > newsize){ fi_shrink(fi); } |
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63 | } |
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64 | |||
65 | newdata = safe_realloc(fi->data, newsize*sizeof(off_t)); |
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66 | if(newsize == 0 || newdata != NULL) |
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67 | { |
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68 | fi->data = newdata; |
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69 | fi->size = newsize; |
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70 | if(fi->fill > fi->size) fi->fill = fi->size; |
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71 | |||
72 | fi->next = fi_next(fi); |
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73 | debug2("new index of size %lu at %p", (unsigned long)fi->size, (void*)fi->data); |
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74 | return 0; |
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75 | } |
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76 | else |
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77 | { |
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78 | error("failed to resize index!"); |
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79 | return -1; |
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80 | } |
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81 | } |
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82 | |||
83 | void fi_add(struct frame_index *fi, off_t pos) |
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84 | { |
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85 | debug3("wanting to add to fill %lu, step %lu, size %lu", (unsigned long)fi->fill, (unsigned long)fi->step, (unsigned long)fi->size); |
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86 | if(fi->fill == fi->size) |
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87 | { /* Index is full, we need to shrink... or grow. */ |
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88 | /* Store the current frame number to check later if we still want it. */ |
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89 | off_t framenum = fi->fill*fi->step; |
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90 | /* If we want not / cannot grow, we shrink. */ |
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91 | if( !(fi->grow_size && fi_resize(fi, fi->size+fi->grow_size)==0) ) |
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92 | fi_shrink(fi); |
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93 | |||
94 | /* Now check if we still want to add this frame (could be that not, because of changed step). */ |
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95 | if(fi->next != framenum) return; |
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96 | } |
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97 | /* When we are here, we want that frame. */ |
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98 | if(fi->fill < fi->size) /* safeguard for size=1, or just generally */ |
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99 | { |
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100 | debug1("adding to index at %p", (void*)(fi->data+fi->fill)); |
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101 | fi->data[fi->fill] = pos; |
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102 | ++fi->fill; |
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103 | fi->next = fi_next(fi); |
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104 | debug3("added pos %li to index with fill %lu and step %lu", (long) pos, (unsigned long)fi->fill, (unsigned long)fi->step); |
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105 | } |
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106 | } |
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107 | |||
3960 | Serge | 108 | int fi_set(struct frame_index *fi, off_t *offsets, off_t step, size_t fill) |
109 | { |
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110 | if(fi_resize(fi, fill) == -1) return -1; |
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111 | fi->step = step; |
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112 | if(offsets != NULL) |
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113 | { |
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114 | memcpy(fi->data, offsets, fill*sizeof(off_t)); |
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115 | fi->fill = fill; |
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116 | } |
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117 | else |
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118 | { |
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119 | /* allocation only, no entries in index yet */ |
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120 | fi->fill = 0; |
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121 | } |
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122 | fi->next = fi_next(fi); |
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123 | debug3("set new index of fill %lu, size %lu at %p", |
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124 | (unsigned long)fi->fill, (unsigned long)fi->size, (void*)fi->data); |
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125 | return 0; |
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126 | } |
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127 | |||
1905 | serge | 128 | void fi_reset(struct frame_index *fi) |
129 | { |
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130 | debug1("reset with size %"SIZE_P, (size_p)fi->size); |
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131 | fi->fill = 0; |
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132 | fi->step = 1; |
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133 | fi->next = fi_next(fi); |
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134 | }>>>> |