| 0,0 → 1,56 |
|---|
| #ifndef MPG123_H_INDEX |
| #define MPG123_H_INDEX |
| |
| /* |
| index: frame index data structure and functions |
| |
| This is for keeping track of frame positions for accurate seeking. |
| Now in it's own file, with initial code from frame.c and parse.c . |
| |
| The idea of the index with a certain amount of entries is to cover |
| all yet-encountered frame positions with minimal coarseness. |
| Meaning: At first every frame position is recorded, then, when |
| the index is full, every second position is trown away to make |
| space. Next time it is full, the same happens. And so on. |
| In this manner we maintain a good resolution with the given |
| maximum index size while covering the whole stream. |
| |
| copyright 2007-8 by the mpg123 project - free software under the terms of the LGPL 2.1 |
| see COPYING and AUTHORS files in distribution or http://mpg123.org |
| initially written by Thomas Orgis |
| */ |
| |
| #include "config.h" |
| #include "compat.h" |
| |
| struct frame_index |
| { |
| off_t *data; /* actual data, the frame positions */ |
| off_t step; /* advancement in frame number per index point */ |
| off_t next; /* frame offset supposed to come next into the index */ |
| size_t size; /* total number of possible entries */ |
| size_t fill; /* number of used entries */ |
| size_t grow_size; /* if > 0: index allowed to grow on need with these steps, instead of lowering resolution */ |
| }; |
| |
| /* The condition for a framenum to be appended to the index. |
| if(FI_NEXT(fr->index, fr->num)) fi_add(offset); */ |
| #define FI_NEXT(fi, framenum) ((fi).size && framenum == (fi).next) |
| |
| /* Initialize stuff, set things to zero and NULL... */ |
| void fi_init(struct frame_index *fi); |
| /* Deallocate/zero things. */ |
| void fi_exit(struct frame_index *fi); |
| |
| /* Prepare a given size, preserving current fill, if possible. |
| If the new size is smaller than fill, the entry density is reduced. |
| Return 0 on success. */ |
| int fi_resize(struct frame_index *fi, size_t newsize); |
| |
| /* Append a frame position, reducing index density if needed. */ |
| void fi_add(struct frame_index *fi, off_t pos); |
| |
| /* Empty the index (setting fill=0 and step=1), but keep current size. */ |
| void fi_reset(struct frame_index *fi); |
| |
| #endif |