// Copyright (c) the JPEG XL Project Authors. All rights reserved.

//

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

#include "lib/jxl/memory_manager_internal.h"

#include <jxl/memory_manager.h>

#include <algorithm>

#include <atomic>

#include <cstddef>

#include <cstdio>

#include <cstdlib>

#include <cstring>     // memcpy

#include <hwy/base.h>  // kMaxVectorSize

#include "lib/jxl/base/common.h"

#include "lib/jxl/base/status.h"

#include "lib/jxl/simd_util.h"

namespace jxl {

namespace {

void* MemoryManagerDefaultAlloc(void* opaque, size_t size) {

  return malloc(size);

}

void MemoryManagerDefaultFree(void* opaque, void* address) { free(address); }

}  // namespace

void* MemoryManagerAlloc(const JxlMemoryManager* memory_manager, size_t size) {

  return memory_manager->alloc(memory_manager->opaque, size);

}

void MemoryManagerFree(const JxlMemoryManager* memory_manager, void* address) {

  memory_manager->free(memory_manager->opaque, address);

}

Status MemoryManagerInit(JxlMemoryManager* self,

                         const JxlMemoryManager* memory_manager) {

  if (memory_manager) {

    *self = *memory_manager;

  } else {

    memset(self, 0, sizeof(*self));

  }

  bool is_default_alloc = (self->alloc == nullptr);

  bool is_default_free = (self->free == nullptr);

  if (is_default_alloc != is_default_free) {

    return false;

  }

  if (is_default_alloc) self->alloc = jxl::MemoryManagerDefaultAlloc;

  if (is_default_free) self->free = jxl::MemoryManagerDefaultFree;

  return true;

}

size_t BytesPerRow(const size_t xsize, const size_t sizeof_t) {

  // Special case: we don't allow any ops -> don't need extra padding/

  if (xsize == 0) {

    return 0;

  }

  const size_t vec_size = MaxVectorSize();

  size_t valid_bytes = xsize * sizeof_t;

  // Allow unaligned accesses starting at the last valid value.

  // Skip for the scalar case because no extra lanes will be loaded.

  if (vec_size != 0) {

    valid_bytes += vec_size - sizeof_t;

  }

  // Round up to vector and cache line size.

  const size_t align = std::max(vec_size, memory_manager_internal::kAlignment);

  size_t bytes_per_row = RoundUpTo(valid_bytes, align);

  // During the lengthy window before writes are committed to memory, CPUs

  // guard against read after write hazards by checking the address, but

  // only the lower 11 bits. We avoid a false dependency between writes to

  // consecutive rows by ensuring their sizes are not multiples of 2 KiB.

  // Avoid2K prevents the same problem for the planes of an Image3.

  if (bytes_per_row % memory_manager_internal::kAlias == 0) {

    bytes_per_row += align;

  }

  JXL_DASSERT(bytes_per_row % align == 0);

  return bytes_per_row;

}

StatusOr<AlignedMemory> AlignedMemory::Create(JxlMemoryManager* memory_manager,

                                              size_t size, size_t pre_padding) {

  JXL_ENSURE(pre_padding <= memory_manager_internal::kAlias);

  size_t allocation_size = size + pre_padding + memory_manager_internal::kAlias;

  if (size > allocation_size) {

    return JXL_FAILURE("Requested allocation is too large");

  }

  JXL_ENSURE(memory_manager);

  void* allocated =

      memory_manager->alloc(memory_manager->opaque, allocation_size);

  if (allocated == nullptr) {

    return JXL_FAILURE("Allocation failed");

  }

  return AlignedMemory(memory_manager, allocated, pre_padding);

}

AlignedMemory::AlignedMemory(JxlMemoryManager* memory_manager, void* allocation,

                             size_t pre_padding)

    : allocation_(allocation), memory_manager_(memory_manager) {

  // Congruence to `offset` (mod kAlias) reduces cache conflicts and load/store

  // stalls, especially with large allocations that would otherwise have similar

  // alignments.

  static std::atomic<uint32_t> next_group{0};

  size_t group =

      static_cast<size_t>(next_group.fetch_add(1, std::memory_order_relaxed));

  group &= (memory_manager_internal::kNumAlignmentGroups - 1);

  size_t offset = memory_manager_internal::kAlignment * group;

  // Actual allocation.

  uintptr_t address = reinterpret_cast<uintptr_t>(allocation) + pre_padding;

  // Aligned address, but might land before allocation (50%/50%) or not have

  // enough pre-padding.

  uintptr_t aligned_address =

      (address & ~(memory_manager_internal::kAlias - 1)) + offset;

  if (aligned_address < address)

    aligned_address += memory_manager_internal::kAlias;

  address_ = reinterpret_cast<void*>(aligned_address);  // NOLINT

}

AlignedMemory::AlignedMemory(AlignedMemory&& other) noexcept {

  allocation_ = other.allocation_;

  memory_manager_ = other.memory_manager_;

  address_ = other.address_;

  other.memory_manager_ = nullptr;

}

AlignedMemory& AlignedMemory::operator=(AlignedMemory&& other) noexcept {

  if (this == &other) return *this;

  if (memory_manager_ && allocation_) {

    memory_manager_->free(memory_manager_->opaque, allocation_);

  }

  allocation_ = other.allocation_;

  memory_manager_ = other.memory_manager_;

  address_ = other.address_;

  other.memory_manager_ = nullptr;

  return *this;

}

AlignedMemory::~AlignedMemory() {

  if (memory_manager_ == nullptr) return;

  memory_manager_->free(memory_manager_->opaque, allocation_);

}

}  // namespace jxl