mirror of
https://github.com/KolibriOS/kolibrios.git
synced 2024-12-20 22:02:34 +03:00
115 lines
3.1 KiB
C
115 lines
3.1 KiB
C
/*
|
|
index: frame index data structure and functions
|
|
|
|
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 "index.h"
|
|
#include "debug.h"
|
|
|
|
/* The next expected frame offset, one step ahead. */
|
|
static off_t fi_next(struct frame_index *fi)
|
|
{
|
|
return (off_t)fi->fill*fi->step;
|
|
}
|
|
|
|
/* Shrink down the used index to the half.
|
|
Be careful with size = 1 ... there's no shrinking possible there. */
|
|
static void fi_shrink(struct frame_index *fi)
|
|
{
|
|
if(fi->fill < 2) return; /* Won't shrink below 1. */
|
|
else
|
|
{ /* Double the step, half the fill. Should work as well for fill%2 = 1 */
|
|
size_t c;
|
|
debug2("shrink index with fill %lu and step %lu", (unsigned long)fi->fill, (unsigned long)fi->step);
|
|
fi->step *= 2;
|
|
fi->fill /= 2;
|
|
/* Move the data down. */
|
|
for(c = 0; c < fi->fill; ++c)
|
|
fi->data[c] = fi->data[2*c];
|
|
}
|
|
|
|
fi->next = fi_next(fi);
|
|
}
|
|
|
|
void fi_init(struct frame_index *fi)
|
|
{
|
|
fi->data = NULL;
|
|
fi->step = 1;
|
|
fi->fill = 0;
|
|
fi->size = 0;
|
|
fi->grow_size = 0;
|
|
fi->next = fi_next(fi);
|
|
}
|
|
|
|
void fi_exit(struct frame_index *fi)
|
|
{
|
|
debug2("fi_exit: %p and %lu", (void*)fi->data, (unsigned long)fi->size);
|
|
if(fi->size && fi->data != NULL) free(fi->data);
|
|
|
|
fi_init(fi); /* Be prepared for further fun, still. */
|
|
}
|
|
|
|
int fi_resize(struct frame_index *fi, size_t newsize)
|
|
{
|
|
off_t *newdata = NULL;
|
|
if(newsize == fi->size) return 0;
|
|
|
|
if(newsize > 0 && newsize < fi->size)
|
|
{ /* When we reduce buffer size a bit, shrink stuff. */
|
|
while(fi->fill > newsize){ fi_shrink(fi); }
|
|
}
|
|
|
|
newdata = safe_realloc(fi->data, newsize*sizeof(off_t));
|
|
if(newsize == 0 || newdata != NULL)
|
|
{
|
|
fi->data = newdata;
|
|
fi->size = newsize;
|
|
if(fi->fill > fi->size) fi->fill = fi->size;
|
|
|
|
fi->next = fi_next(fi);
|
|
debug2("new index of size %lu at %p", (unsigned long)fi->size, (void*)fi->data);
|
|
return 0;
|
|
}
|
|
else
|
|
{
|
|
error("failed to resize index!");
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
void fi_add(struct frame_index *fi, off_t pos)
|
|
{
|
|
debug3("wanting to add to fill %lu, step %lu, size %lu", (unsigned long)fi->fill, (unsigned long)fi->step, (unsigned long)fi->size);
|
|
if(fi->fill == fi->size)
|
|
{ /* Index is full, we need to shrink... or grow. */
|
|
/* Store the current frame number to check later if we still want it. */
|
|
off_t framenum = fi->fill*fi->step;
|
|
/* If we want not / cannot grow, we shrink. */
|
|
if( !(fi->grow_size && fi_resize(fi, fi->size+fi->grow_size)==0) )
|
|
fi_shrink(fi);
|
|
|
|
/* Now check if we still want to add this frame (could be that not, because of changed step). */
|
|
if(fi->next != framenum) return;
|
|
}
|
|
/* When we are here, we want that frame. */
|
|
if(fi->fill < fi->size) /* safeguard for size=1, or just generally */
|
|
{
|
|
debug1("adding to index at %p", (void*)(fi->data+fi->fill));
|
|
fi->data[fi->fill] = pos;
|
|
++fi->fill;
|
|
fi->next = fi_next(fi);
|
|
debug3("added pos %li to index with fill %lu and step %lu", (long) pos, (unsigned long)fi->fill, (unsigned long)fi->step);
|
|
}
|
|
}
|
|
|
|
void fi_reset(struct frame_index *fi)
|
|
{
|
|
debug1("reset with size %"SIZE_P, (size_p)fi->size);
|
|
fi->fill = 0;
|
|
fi->step = 1;
|
|
fi->next = fi_next(fi);
|
|
}
|