| /* |
| * Copyright 2017 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can |
| * be found in the LICENSE file. |
| * |
| */ |
| |
| #pragma once |
| |
| // |
| // |
| // |
| |
| #include "skc.h" |
| #include "weakref.h" |
| #include "macros.h" |
| |
| // |
| // WEAKREF |
| // |
| |
| #define SKC_WEAKREF_INDEX_BITS 16 // max bits for a weakref index -- this could/should be 12 bits |
| #define SKC_WEAKREF_INDEX_COUNT (1u << SKC_WEAKREF_INDEX_BITS) |
| |
| #define SKC_WEAKREF_INDEX_MASK SKC_BITS_TO_MASK(SKC_WEAKREF_INDEX_BITS) |
| #define SKC_WEAKREF_EPOCH_MASK SKC_BITS_TO_MASK_AT_64(64-SKC_WEAKREF_INDEX_BITS,SKC_WEAKREF_INDEX_BITS) |
| |
| #define SKC_WEAKREF_EPOCH_INIT 0ul |
| #define SKC_WEAKREF_EPOCH_ONE SKC_BITS_TO_MASK_AT_64(1,SKC_WEAKREF_INDEX_BITS) |
| |
| // |
| // FIXME -- ASSUMES LITTLE-ENDIAN |
| // |
| |
| union skc_weakref |
| { |
| skc_weakref_t u64; // 64-bits containing refutation epoch and an index |
| |
| struct { |
| skc_uint index : SKC_WEAKREF_INDEX_BITS; |
| skc_uint na_lo : 32 - SKC_WEAKREF_INDEX_BITS; |
| skc_uint na_hi; |
| }; |
| |
| struct { |
| skc_ulong : SKC_WEAKREF_INDEX_BITS; |
| skc_ulong epoch : 64 - SKC_WEAKREF_INDEX_BITS; |
| }; |
| }; |
| |
| SKC_STATIC_ASSERT(sizeof(skc_weakref_t) == sizeof(skc_ulong)); |
| SKC_STATIC_ASSERT(sizeof(union skc_weakref) == sizeof(skc_ulong)); |
| |
| // |
| // |
| // |
| |
| void |
| skc_weakref_epoch_init(skc_epoch_t * const epoch) |
| { |
| *epoch = SKC_WEAKREF_EPOCH_INIT; |
| } |
| |
| void |
| skc_weakref_epoch_inc(skc_epoch_t * const epoch) |
| { |
| *epoch += SKC_WEAKREF_EPOCH_ONE; |
| } |
| |
| void |
| skc_weakref_init(skc_weakref_t * const weakref, |
| skc_epoch_t * const epoch, |
| skc_uint const index) |
| { |
| *weakref = *epoch | (index & SKC_WEAKREF_INDEX_MASK); |
| } |
| |
| bool |
| skc_weakref_is_invalid(skc_weakref_t const * const weakref, |
| skc_epoch_t const * const epoch) |
| { |
| return ((*weakref ^ *epoch) & SKC_WEAKREF_EPOCH_MASK) != 0UL; |
| } |
| |
| skc_uint |
| skc_weakref_index(skc_weakref_t const * const weakref) |
| { |
| // truncate to word and mask |
| return (skc_uint)*weakref & SKC_WEAKREF_INDEX_MASK; |
| } |
| |
| // |
| // |
| // |