// 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.

#ifndef LIB_JXL_BASE_FLOAT_H_

#define LIB_JXL_BASE_FLOAT_H_

#include <jxl/types.h>

#include <stddef.h>

#include <stdint.h>

#include <string.h>

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

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

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

namespace jxl {

namespace detail {

static JXL_INLINE float LoadFloat16(uint16_t bits16) {

  const uint32_t sign = bits16 >> 15;

  const uint32_t biased_exp = (bits16 >> 10) & 0x1F;

  const uint32_t mantissa = bits16 & 0x3FF;

  // Subnormal or zero

  if (biased_exp == 0) {

    const float subnormal =

        (1.0f / 16384) * (static_cast<float>(mantissa) * (1.0f / 1024));

    return sign ? -subnormal : subnormal;

  }

  // Normalized: convert the representation directly (faster than ldexp/tables).

  const uint32_t biased_exp32 =

      biased_exp == 0b11111 ? 0b11111111 : biased_exp + (127 - 15);

  const uint32_t mantissa32 = mantissa << (23 - 10);

  const uint32_t bits32 = (sign << 31) | (biased_exp32 << 23) | mantissa32;

  float result;

  memcpy(&result, &bits32, 4);

  return result;

}

}  // namespace detail

template <typename SaveFloatAtFn>

static Status JXL_INLINE LoadFloatRow(const uint8_t* src, size_t count,

                                      size_t stride, JxlDataType type,

                                      bool little_endian, float scale,

                                      SaveFloatAtFn callback) {

  switch (type) {

    case JXL_TYPE_FLOAT:

      if (little_endian) {

        for (size_t i = 0; i < count; ++i) {

          callback(i, LoadLEFloat(src + stride * i));

        }

      } else {

        for (size_t i = 0; i < count; ++i) {

          callback(i, LoadBEFloat(src + stride * i));

        }

      }

      return true;

    case JXL_TYPE_UINT8:

      for (size_t i = 0; i < count; ++i) {

        callback(i, src[stride * i] * scale);

      }

      return true;

    case JXL_TYPE_UINT16:

      if (little_endian) {

        for (size_t i = 0; i < count; ++i) {

          callback(i, LoadLE16(src + stride * i) * scale);

        }

      } else {

        for (size_t i = 0; i < count; ++i) {

          callback(i, LoadBE16(src + stride * i) * scale);

        }

      }

      return true;

    case JXL_TYPE_FLOAT16:

      if (little_endian) {

        for (size_t i = 0; i < count; ++i) {

          callback(i, detail::LoadFloat16(LoadLE16(src + stride * i)));

        }

      } else {

        for (size_t i = 0; i < count; ++i) {

          callback(i, detail::LoadFloat16(LoadBE16(src + stride * i)));

        }

      }

      return true;

    default:

      return JXL_FAILURE("Unsupported sample format");

  }

}

}  // namespace jxl

#endif  // LIB_JXL_BASE_FLOAT_H_