Rev 1905 | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 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 | } |