PackedArray.h

 
#ifndef POMYANG_KPARENT_INC_PACKEDARRAY_H_
#define POMYANG_KPARENT_INC_PACKEDARRAY_H_
 
#ifdef __cplusplus
extern "C" {
#endif
 
#include <omp.h>
#include <stdint.h>
 
/*
 
PackedArray principle:
  . compact storage of <= 32 bits items
  . items are tightly packed into a buffer of uint32_t integers
 
PackedArray requirements:
  . you must know in advance how many bits are needed to hold a single item
  . you must know in advance how many items you want to store
  . when packing, behavior is undefined if items have more than bitsPerItem bits
 
PackedArray general in memory representation:
  |-------------------------------------------------- - - -
  |       b0       |       b1       |       b2       |
  |-------------------------------------------------- - - -
  | i0 | i1 | i2 | i3 | i4 | i5 | i6 | i7 | i8 | i9 |
  |-------------------------------------------------- - - -
 
  . items are tightly packed together
  . several items end up inside the same buffer cell, e.g. i0, i1, i2
  . some items span two buffer cells, e.g. i3, i6
 
*/
 
typedef struct {
    uint32_t num_locks;
    uint32_t lock_interval;
    omp_lock_t* locks;
} lock_info_t;
 
typedef struct {
    uint32_t bitsPerItem;
    uint64_t count;
    lock_info_t lock_info;
    uint32_t padding[2];
    uint32_t buffer[];
} PackedArray;
 
// creation / destruction
PackedArray* PackedArray_create(uint32_t bitsPerItem, uint64_t count, uint32_t num_locks);
void PackedArray_destroy(PackedArray* a);
uint64_t PackedArray_estimate_heap(uint32_t bitsPerItem, uint64_t count, uint32_t num_locks);
 
// packing / unpacking
// offset is expressed in number of elements
void PackedArray_pack(PackedArray* a, const uint64_t offset, const uint32_t* in, uint64_t count);
void PackedArray_unpack(const PackedArray* a, const uint64_t offset, uint32_t* out, uint64_t count);
 
// single item access
void PackedArray_set(PackedArray* a, const uint64_t offset, const uint32_t in);
uint32_t PackedArray_get(const PackedArray* a, const uint64_t offset);
 
// helpers
uint32_t PackedArray_bufferSize(const PackedArray* a);
uint32_t PackedArray_computeBitsPerItem(const uint32_t* in, uint64_t count);
void PackedArray_unlock_offset(PackedArray* a, const uint64_t offset);
void PackedArray_lock_offset(PackedArray* a, const uint64_t offset);
#ifdef __cplusplus
}
#endif
 
#endif  // POMYANG_KPARENT_INC_PACKEDARRAY_H_