mirror of
https://github.com/FWGS/xash3d-fwgs
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156 lines
3.2 KiB
C
156 lines
3.2 KiB
C
/*
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index.c - compact version of famous library mpg123
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Copyright (C) 2017 Uncle Mike
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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*/
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#include "mpg123.h"
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#include "index.h"
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// the next expected frame offset, one step ahead.
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static mpg_off_t fi_next( frame_index_t *fi )
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{
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return (mpg_off_t)fi->fill*fi->step;
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}
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// shrink down the used index to the half.
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// be careful with size = 1 ... there's no shrinking possible there.
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static void fi_shrink( frame_index_t *fi )
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{
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if( fi->fill < 2 )
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{
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return; // won't shrink below 1.
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}
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else
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{
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size_t c;
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// double the step, half the fill. Should work as well for fill%2 = 1
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fi->step *= 2;
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fi->fill /= 2;
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// move the data down.
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for( c = 0; c < fi->fill; ++c )
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fi->data[c] = fi->data[2*c];
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}
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fi->next = fi_next( fi );
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}
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void fi_init( frame_index_t *fi )
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{
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fi->data = NULL;
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fi->step = 1;
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fi->fill = 0;
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fi->size = 0;
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fi->grow_size = 0;
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fi->next = fi_next( fi );
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}
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void fi_exit( frame_index_t *fi )
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{
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if( fi->size && fi->data != NULL )
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free( fi->data );
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fi_init( fi ); // be prepared for further fun, still.
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}
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int fi_resize( frame_index_t *fi, size_t newsize )
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{
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mpg_off_t *newdata = NULL;
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if( newsize == fi->size )
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return 0;
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if( newsize > 0 && newsize < fi->size )
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{
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// when we reduce buffer size a bit, shrink stuff.
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while( fi->fill > newsize )
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fi_shrink( fi );
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}
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newdata = realloc( fi->data, newsize * sizeof( mpg_off_t ));
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if( newsize == 0 || newdata != NULL )
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{
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fi->data = newdata;
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fi->size = newsize;
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if( fi->fill > fi->size )
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fi->fill = fi->size;
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fi->next = fi_next( fi );
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return 0;
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}
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else
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{
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return -1;
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}
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}
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void fi_add( frame_index_t *fi, mpg_off_t pos )
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{
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if( fi->fill == fi->size )
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{
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mpg_off_t framenum = fi->fill*fi->step;
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// index is full, we need to shrink... or grow.
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// store the current frame number to check later if we still want it.
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// if we want not / cannot grow, we shrink.
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if( !( fi->grow_size && fi_resize( fi, fi->size+fi->grow_size ) == 0 ))
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fi_shrink( fi );
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// now check if we still want to add this frame (could be that not, because of changed step).
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if( fi->next != framenum )
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return;
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}
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// when we are here, we want that frame.
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if( fi->fill < fi->size ) // safeguard for size = 1, or just generally
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{
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fi->data[fi->fill] = pos;
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fi->fill++;
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fi->next = fi_next( fi );
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}
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}
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int fi_set( frame_index_t *fi, mpg_off_t *offsets, mpg_off_t step, size_t fill )
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{
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if( fi_resize( fi, fill ) == -1 )
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return -1;
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fi->step = step;
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if( offsets != NULL )
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{
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memcpy( fi->data, offsets, fill * sizeof( mpg_off_t ));
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fi->fill = fill;
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}
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else
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{
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// allocation only, no entries in index yet
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fi->fill = 0;
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}
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fi->next = fi_next( fi );
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return 0;
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}
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void fi_reset( frame_index_t *fi )
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{
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fi->fill = 0;
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fi->step = 1;
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fi->next = fi_next( fi );
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}
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