--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/decoders/libmpg123/index.c	Fri Jan 30 02:44:47 2009 -0500
@@ -0,0 +1,114 @@
+/*
+	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 %zu", fi->size);
+	fi->fill = 0;
+	fi->step = 1;
+	fi->next = fi_next(fi);
+}