77 lines
2 KiB
C
77 lines
2 KiB
C
|
#ifndef _ROSE_COMPRESSION_RLE_IMPL_H__
|
||
|
|
#define _ROSE_COMPRESSION_RLE_IMPL_H__
|
||
|
|
|
||
|
|
// Copyright 2007 Google Inc. All Rights Reserved.
|
||
|
|
// Author: sears@google.com (Rusty Sears)
|
||
|
|
|
||
|
|
#include <assert.h>
|
||
|
|
|
||
|
|
#include "rle.h"
|
||
|
|
|
||
|
|
|
||
|
|
namespace rose {
|
||
|
|
/**
|
||
|
|
Store a new value in run length encoding. If this value matches
|
||
|
|
the previous one, increment a counter. Otherwise, create a new
|
||
|
|
triple_t to hold the new value and its count. Most of the
|
||
|
|
complexity comes from dealing with integer overflow, and running
|
||
|
|
out of space.
|
||
|
|
*/
|
||
|
|
template <class TYPE>
|
||
|
|
inline slot_index_t
|
||
|
|
Rle<TYPE>::append(int xid, const TYPE dat,
|
||
|
|
byte_off_t* except, byte * exceptions, //char *exceptional,
|
||
|
|
int *free_bytes) {
|
||
|
|
int64_t ret;
|
||
|
|
|
||
|
|
ret = last_block_ptr()->index + last_block_ptr()->copies;
|
||
|
|
|
||
|
|
if (dat != last_block_ptr()->data ||
|
||
|
|
last_block_ptr()->copies == MAX_COPY_COUNT) {
|
||
|
|
// this key is not the same as the last one, or
|
||
|
|
// the block is full
|
||
|
|
|
||
|
|
*free_bytes -= sizeof(triple_t);
|
||
|
|
|
||
|
|
// Write the changes in our overrun space
|
||
|
|
triple_t *n = new_block_ptr();
|
||
|
|
n->index = ret;
|
||
|
|
n->copies = 1;
|
||
|
|
n->data = dat;
|
||
|
|
|
||
|
|
// Finalize the changes unless we're out of space
|
||
|
|
(*block_count_ptr()) += (*free_bytes >= 0);
|
||
|
|
|
||
|
|
} else if(ret == MAX_INDEX) {
|
||
|
|
// out of address space
|
||
|
|
*free_bytes = -1;
|
||
|
|
ret = NOSPACE;
|
||
|
|
} else {
|
||
|
|
// success; bump number of copies of this item, and return.
|
||
|
|
last_block_ptr()->copies++;
|
||
|
|
}
|
||
|
|
|
||
|
|
return (slot_index_t)ret;
|
||
|
|
}
|
||
|
|
template <class TYPE>
|
||
|
|
inline TYPE *
|
||
|
|
Rle<TYPE>::recordRead(int xid, slot_index_t slot, byte* exceptions,
|
||
|
|
TYPE * scratch) {
|
||
|
|
block_index_t n = nth_block_ptr(last_)->index <= slot ? last_ : 0;
|
||
|
|
// while (n < *block_count_ptr()) {
|
||
|
|
do {
|
||
|
|
triple_t * t = nth_block_ptr(n);
|
||
|
|
if (t->index <= slot && t->index + t->copies > slot) {
|
||
|
|
*scratch = t->data;
|
||
|
|
last_ = n;
|
||
|
|
return scratch;
|
||
|
|
}
|
||
|
|
n++;
|
||
|
|
} while (n < *block_count_ptr());
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
} // namespace rose
|
||
|
|
|
||
|
|
#endif // _ROSE_COMPRESSION_RLE_IMPL_H__
|