Initial work on Vulkan:

-Added VulkanContext
-Added an X11 implementation
-Added a rendering device abstraction
-added a Vulkan rendering device abstraction
-Engine does not work, only shows Godot logo (run it from bin/)

1 files changed, 1078 insertions, 0 deletions

diff --git a/thirdparty/glslang/SPIRV/hex_float.h b/thirdparty/glslang/SPIRV/hex_float.h
new file mode 100644
index 0000000000..905b21a45a
--- /dev/null
+++ b/thirdparty/glslang/SPIRV/hex_float.h
@@ -0,0 +1,1078 @@
+// Copyright (c) 2015-2016 The Khronos Group Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef LIBSPIRV_UTIL_HEX_FLOAT_H_
+#define LIBSPIRV_UTIL_HEX_FLOAT_H_
+
+#include <cassert>
+#include <cctype>
+#include <cmath>
+#include <cstdint>
+#include <iomanip>
+#include <limits>
+#include <sstream>
+
+#if defined(_MSC_VER) && _MSC_VER < 1800
+namespace std {
+bool isnan(double f)
+{
+  return ::_isnan(f) != 0;
+}
+bool isinf(double f)
+{
+  return ::_finite(f) == 0;
+}
+}
+#endif
+
+#include "bitutils.h"
+
+namespace spvutils {
+
+class Float16 {
+ public:
+  Float16(uint16_t v) : val(v) {}
+  Float16() {}
+  static bool isNan(const Float16& val) {
+    return ((val.val & 0x7C00) == 0x7C00) && ((val.val & 0x3FF) != 0);
+  }
+  // Returns true if the given value is any kind of infinity.
+  static bool isInfinity(const Float16& val) {
+    return ((val.val & 0x7C00) == 0x7C00) && ((val.val & 0x3FF) == 0);
+  }
+  Float16(const Float16& other) { val = other.val; }
+  uint16_t get_value() const { return val; }
+
+  // Returns the maximum normal value.
+  static Float16 max() { return Float16(0x7bff); }
+  // Returns the lowest normal value.
+  static Float16 lowest() { return Float16(0xfbff); }
+
+ private:
+  uint16_t val;
+};
+
+// To specialize this type, you must override uint_type to define
+// an unsigned integer that can fit your floating point type.
+// You must also add a isNan function that returns true if
+// a value is Nan.
+template <typename T>
+struct FloatProxyTraits {
+  typedef void uint_type;
+};
+
+template <>
+struct FloatProxyTraits<float> {
+  typedef uint32_t uint_type;
+  static bool isNan(float f) { return std::isnan(f); }
+  // Returns true if the given value is any kind of infinity.
+  static bool isInfinity(float f) { return std::isinf(f); }
+  // Returns the maximum normal value.
+  static float max() { return std::numeric_limits<float>::max(); }
+  // Returns the lowest normal value.
+  static float lowest() { return std::numeric_limits<float>::lowest(); }
+};
+
+template <>
+struct FloatProxyTraits<double> {
+  typedef uint64_t uint_type;
+  static bool isNan(double f) { return std::isnan(f); }
+  // Returns true if the given value is any kind of infinity.
+  static bool isInfinity(double f) { return std::isinf(f); }
+  // Returns the maximum normal value.
+  static double max() { return std::numeric_limits<double>::max(); }
+  // Returns the lowest normal value.
+  static double lowest() { return std::numeric_limits<double>::lowest(); }
+};
+
+template <>
+struct FloatProxyTraits<Float16> {
+  typedef uint16_t uint_type;
+  static bool isNan(Float16 f) { return Float16::isNan(f); }
+  // Returns true if the given value is any kind of infinity.
+  static bool isInfinity(Float16 f) { return Float16::isInfinity(f); }
+  // Returns the maximum normal value.
+  static Float16 max() { return Float16::max(); }
+  // Returns the lowest normal value.
+  static Float16 lowest() { return Float16::lowest(); }
+};
+
+// Since copying a floating point number (especially if it is NaN)
+// does not guarantee that bits are preserved, this class lets us
+// store the type and use it as a float when necessary.
+template <typename T>
+class FloatProxy {
+ public:
+  typedef typename FloatProxyTraits<T>::uint_type uint_type;
+
+  // Since this is to act similar to the normal floats,
+  // do not initialize the data by default.
+  FloatProxy() {}
+
+  // Intentionally non-explicit. This is a proxy type so
+  // implicit conversions allow us to use it more transparently.
+  FloatProxy(T val) { data_ = BitwiseCast<uint_type>(val); }
+
+  // Intentionally non-explicit. This is a proxy type so
+  // implicit conversions allow us to use it more transparently.
+  FloatProxy(uint_type val) { data_ = val; }
+
+  // This is helpful to have and is guaranteed not to stomp bits.
+  FloatProxy<T> operator-() const {
+    return static_cast<uint_type>(data_ ^
+                                  (uint_type(0x1) << (sizeof(T) * 8 - 1)));
+  }
+
+  // Returns the data as a floating point value.
+  T getAsFloat() const { return BitwiseCast<T>(data_); }
+
+  // Returns the raw data.
+  uint_type data() const { return data_; }
+
+  // Returns true if the value represents any type of NaN.
+  bool isNan() { return FloatProxyTraits<T>::isNan(getAsFloat()); }
+  // Returns true if the value represents any type of infinity.
+  bool isInfinity() { return FloatProxyTraits<T>::isInfinity(getAsFloat()); }
+
+  // Returns the maximum normal value.
+  static FloatProxy<T> max() {
+    return FloatProxy<T>(FloatProxyTraits<T>::max());
+  }
+  // Returns the lowest normal value.
+  static FloatProxy<T> lowest() {
+    return FloatProxy<T>(FloatProxyTraits<T>::lowest());
+  }
+
+ private:
+  uint_type data_;
+};
+
+template <typename T>
+bool operator==(const FloatProxy<T>& first, const FloatProxy<T>& second) {
+  return first.data() == second.data();
+}
+
+// Reads a FloatProxy value as a normal float from a stream.
+template <typename T>
+std::istream& operator>>(std::istream& is, FloatProxy<T>& value) {
+  T float_val;
+  is >> float_val;
+  value = FloatProxy<T>(float_val);
+  return is;
+}
+
+// This is an example traits. It is not meant to be used in practice, but will
+// be the default for any non-specialized type.
+template <typename T>
+struct HexFloatTraits {
+  // Integer type that can store this hex-float.
+  typedef void uint_type;
+  // Signed integer type that can store this hex-float.
+  typedef void int_type;
+  // The numerical type that this HexFloat represents.
+  typedef void underlying_type;
+  // The type needed to construct the underlying type.
+  typedef void native_type;
+  // The number of bits that are actually relevant in the uint_type.
+  // This allows us to deal with, for example, 24-bit values in a 32-bit
+  // integer.
+  static const uint32_t num_used_bits = 0;
+  // Number of bits that represent the exponent.
+  static const uint32_t num_exponent_bits = 0;
+  // Number of bits that represent the fractional part.
+  static const uint32_t num_fraction_bits = 0;
+  // The bias of the exponent. (How much we need to subtract from the stored
+  // value to get the correct value.)
+  static const uint32_t exponent_bias = 0;
+};
+
+// Traits for IEEE float.
+// 1 sign bit, 8 exponent bits, 23 fractional bits.
+template <>
+struct HexFloatTraits<FloatProxy<float>> {
+  typedef uint32_t uint_type;
+  typedef int32_t int_type;
+  typedef FloatProxy<float> underlying_type;
+  typedef float native_type;
+  static const uint_type num_used_bits = 32;
+  static const uint_type num_exponent_bits = 8;
+  static const uint_type num_fraction_bits = 23;
+  static const uint_type exponent_bias = 127;
+};
+
+// Traits for IEEE double.
+// 1 sign bit, 11 exponent bits, 52 fractional bits.
+template <>
+struct HexFloatTraits<FloatProxy<double>> {
+  typedef uint64_t uint_type;
+  typedef int64_t int_type;
+  typedef FloatProxy<double> underlying_type;
+  typedef double native_type;
+  static const uint_type num_used_bits = 64;
+  static const uint_type num_exponent_bits = 11;
+  static const uint_type num_fraction_bits = 52;
+  static const uint_type exponent_bias = 1023;
+};
+
+// Traits for IEEE half.
+// 1 sign bit, 5 exponent bits, 10 fractional bits.
+template <>
+struct HexFloatTraits<FloatProxy<Float16>> {
+  typedef uint16_t uint_type;
+  typedef int16_t int_type;
+  typedef uint16_t underlying_type;
+  typedef uint16_t native_type;
+  static const uint_type num_used_bits = 16;
+  static const uint_type num_exponent_bits = 5;
+  static const uint_type num_fraction_bits = 10;
+  static const uint_type exponent_bias = 15;
+};
+
+enum round_direction {
+  kRoundToZero,
+  kRoundToNearestEven,
+  kRoundToPositiveInfinity,
+  kRoundToNegativeInfinity
+};
+
+// Template class that houses a floating pointer number.
+// It exposes a number of constants based on the provided traits to
+// assist in interpreting the bits of the value.
+template <typename T, typename Traits = HexFloatTraits<T>>
+class HexFloat {
+ public:
+  typedef typename Traits::uint_type uint_type;
+  typedef typename Traits::int_type int_type;
+  typedef typename Traits::underlying_type underlying_type;
+  typedef typename Traits::native_type native_type;
+
+  explicit HexFloat(T f) : value_(f) {}
+
+  T value() const { return value_; }
+  void set_value(T f) { value_ = f; }
+
+  // These are all written like this because it is convenient to have
+  // compile-time constants for all of these values.
+
+  // Pass-through values to save typing.
+  static const uint32_t num_used_bits = Traits::num_used_bits;
+  static const uint32_t exponent_bias = Traits::exponent_bias;
+  static const uint32_t num_exponent_bits = Traits::num_exponent_bits;
+  static const uint32_t num_fraction_bits = Traits::num_fraction_bits;
+
+  // Number of bits to shift left to set the highest relevant bit.
+  static const uint32_t top_bit_left_shift = num_used_bits - 1;
+  // How many nibbles (hex characters) the fractional part takes up.
+  static const uint32_t fraction_nibbles = (num_fraction_bits + 3) / 4;
+  // If the fractional part does not fit evenly into a hex character (4-bits)
+  // then we have to left-shift to get rid of leading 0s. This is the amount
+  // we have to shift (might be 0).
+  static const uint32_t num_overflow_bits =
+      fraction_nibbles * 4 - num_fraction_bits;
+
+  // The representation of the fraction, not the actual bits. This
+  // includes the leading bit that is usually implicit.
+  static const uint_type fraction_represent_mask =
+      spvutils::SetBits<uint_type, 0,
+                        num_fraction_bits + num_overflow_bits>::get;
+
+  // The topmost bit in the nibble-aligned fraction.
+  static const uint_type fraction_top_bit =
+      uint_type(1) << (num_fraction_bits + num_overflow_bits - 1);
+
+  // The least significant bit in the exponent, which is also the bit
+  // immediately to the left of the significand.
+  static const uint_type first_exponent_bit = uint_type(1)
+                                              << (num_fraction_bits);
+
+  // The mask for the encoded fraction. It does not include the
+  // implicit bit.
+  static const uint_type fraction_encode_mask =
+      spvutils::SetBits<uint_type, 0, num_fraction_bits>::get;
+
+  // The bit that is used as a sign.
+  static const uint_type sign_mask = uint_type(1) << top_bit_left_shift;
+
+  // The bits that represent the exponent.
+  static const uint_type exponent_mask =
+      spvutils::SetBits<uint_type, num_fraction_bits, num_exponent_bits>::get;
+
+  // How far left the exponent is shifted.
+  static const uint32_t exponent_left_shift = num_fraction_bits;
+
+  // How far from the right edge the fraction is shifted.
+  static const uint32_t fraction_right_shift =
+      static_cast<uint32_t>(sizeof(uint_type) * 8) - num_fraction_bits;
+
+  // The maximum representable unbiased exponent.
+  static const int_type max_exponent =
+      (exponent_mask >> num_fraction_bits) - exponent_bias;
+  // The minimum representable exponent for normalized numbers.
+  static const int_type min_exponent = -static_cast<int_type>(exponent_bias);
+
+  // Returns the bits associated with the value.
+  uint_type getBits() const { return spvutils::BitwiseCast<uint_type>(value_); }
+
+  // Returns the bits associated with the value, without the leading sign bit.
+  uint_type getUnsignedBits() const {
+    return static_cast<uint_type>(spvutils::BitwiseCast<uint_type>(value_) &
+                                  ~sign_mask);
+  }
+
+  // Returns the bits associated with the exponent, shifted to start at the
+  // lsb of the type.
+  const uint_type getExponentBits() const {
+    return static_cast<uint_type>((getBits() & exponent_mask) >>
+                                  num_fraction_bits);
+  }
+
+  // Returns the exponent in unbiased form. This is the exponent in the
+  // human-friendly form.
+  const int_type getUnbiasedExponent() const {
+    return static_cast<int_type>(getExponentBits() - exponent_bias);
+  }
+
+  // Returns just the significand bits from the value.
+  const uint_type getSignificandBits() const {
+    return getBits() & fraction_encode_mask;
+  }
+
+  // If the number was normalized, returns the unbiased exponent.
+  // If the number was denormal, normalize the exponent first.
+  const int_type getUnbiasedNormalizedExponent() const {
+    if ((getBits() & ~sign_mask) == 0) {  // special case if everything is 0
+      return 0;
+    }
+    int_type exp = getUnbiasedExponent();
+    if (exp == min_exponent) {  // We are in denorm land.
+      uint_type significand_bits = getSignificandBits();
+      while ((significand_bits & (first_exponent_bit >> 1)) == 0) {
+        significand_bits = static_cast<uint_type>(significand_bits << 1);
+        exp = static_cast<int_type>(exp - 1);
+      }
+      significand_bits &= fraction_encode_mask;
+    }
+    return exp;
+  }
+
+  // Returns the signficand after it has been normalized.
+  const uint_type getNormalizedSignificand() const {
+    int_type unbiased_exponent = getUnbiasedNormalizedExponent();
+    uint_type significand = getSignificandBits();
+    for (int_type i = unbiased_exponent; i <= min_exponent; ++i) {
+      significand = static_cast<uint_type>(significand << 1);
+    }
+    significand &= fraction_encode_mask;
+    return significand;
+  }
+
+  // Returns true if this number represents a negative value.
+  bool isNegative() const { return (getBits() & sign_mask) != 0; }
+
+  // Sets this HexFloat from the individual components.
+  // Note this assumes EVERY significand is normalized, and has an implicit
+  // leading one. This means that the only way that this method will set 0,
+  // is if you set a number so denormalized that it underflows.
+  // Do not use this method with raw bits extracted from a subnormal number,
+  // since subnormals do not have an implicit leading 1 in the significand.
+  // The significand is also expected to be in the
+  // lowest-most num_fraction_bits of the uint_type.
+  // The exponent is expected to be unbiased, meaning an exponent of
+  // 0 actually means 0.
+  // If underflow_round_up is set, then on underflow, if a number is non-0
+  // and would underflow, we round up to the smallest denorm.
+  void setFromSignUnbiasedExponentAndNormalizedSignificand(
+      bool negative, int_type exponent, uint_type significand,
+      bool round_denorm_up) {
+    bool significand_is_zero = significand == 0;
+
+    if (exponent <= min_exponent) {
+      // If this was denormalized, then we have to shift the bit on, meaning
+      // the significand is not zero.
+      significand_is_zero = false;
+      significand |= first_exponent_bit;
+      significand = static_cast<uint_type>(significand >> 1);
+    }
+
+    while (exponent < min_exponent) {
+      significand = static_cast<uint_type>(significand >> 1);
+      ++exponent;
+    }
+
+    if (exponent == min_exponent) {
+      if (significand == 0 && !significand_is_zero && round_denorm_up) {
+        significand = static_cast<uint_type>(0x1);
+      }
+    }
+
+    uint_type new_value = 0;
+    if (negative) {
+      new_value = static_cast<uint_type>(new_value | sign_mask);
+    }
+    exponent = static_cast<int_type>(exponent + exponent_bias);
+    assert(exponent >= 0);
+
+    // put it all together
+    exponent = static_cast<uint_type>((exponent << exponent_left_shift) &
+                                      exponent_mask);
+    significand = static_cast<uint_type>(significand & fraction_encode_mask);
+    new_value = static_cast<uint_type>(new_value | (exponent | significand));
+    value_ = BitwiseCast<T>(new_value);
+  }
+
+  // Increments the significand of this number by the given amount.
+  // If this would spill the significand into the implicit bit,
+  // carry is set to true and the significand is shifted to fit into
+  // the correct location, otherwise carry is set to false.
+  // All significands and to_increment are assumed to be within the bounds
+  // for a valid significand.
+  static uint_type incrementSignificand(uint_type significand,
+                                        uint_type to_increment, bool* carry) {
+    significand = static_cast<uint_type>(significand + to_increment);
+    *carry = false;
+    if (significand & first_exponent_bit) {
+      *carry = true;
+      // The implicit 1-bit will have carried, so we should zero-out the
+      // top bit and shift back.
+      significand = static_cast<uint_type>(significand & ~first_exponent_bit);
+      significand = static_cast<uint_type>(significand >> 1);
+    }
+    return significand;
+  }
+
+  // These exist because MSVC throws warnings on negative right-shifts
+  // even if they are not going to be executed. Eg:
+  // constant_number < 0? 0: constant_number
+  // These convert the negative left-shifts into right shifts.
+
+  template <typename int_type>
+  uint_type negatable_left_shift(int_type N, uint_type val)
+  {
+    if(N >= 0)
+      return val << N;
+
+    return val >> -N;
+  }
+
+  template <typename int_type>
+  uint_type negatable_right_shift(int_type N, uint_type val)
+  {
+    if(N >= 0)
+      return val >> N;
+
+    return val << -N;
+  }
+
+  // Returns the significand, rounded to fit in a significand in
+  // other_T. This is shifted so that the most significant
+  // bit of the rounded number lines up with the most significant bit
+  // of the returned significand.
+  template <typename other_T>
+  typename other_T::uint_type getRoundedNormalizedSignificand(
+      round_direction dir, bool* carry_bit) {
+    typedef typename other_T::uint_type other_uint_type;
+    static const int_type num_throwaway_bits =
+        static_cast<int_type>(num_fraction_bits) -
+        static_cast<int_type>(other_T::num_fraction_bits);
+
+    static const uint_type last_significant_bit =
+        (num_throwaway_bits < 0)
+            ? 0
+            : negatable_left_shift(num_throwaway_bits, 1u);
+    static const uint_type first_rounded_bit =
+        (num_throwaway_bits < 1)
+            ? 0
+            : negatable_left_shift(num_throwaway_bits - 1, 1u);
+
+    static const uint_type throwaway_mask_bits =
+        num_throwaway_bits > 0 ? num_throwaway_bits : 0;
+    static const uint_type throwaway_mask =
+        spvutils::SetBits<uint_type, 0, throwaway_mask_bits>::get;
+
+    *carry_bit = false;
+    other_uint_type out_val = 0;
+    uint_type significand = getNormalizedSignificand();
+    // If we are up-casting, then we just have to shift to the right location.
+    if (num_throwaway_bits <= 0) {
+      out_val = static_cast<other_uint_type>(significand);
+      uint_type shift_amount = static_cast<uint_type>(-num_throwaway_bits);
+      out_val = static_cast<other_uint_type>(out_val << shift_amount);
+      return out_val;
+    }
+
+    // If every non-representable bit is 0, then we don't have any casting to
+    // do.
+    if ((significand & throwaway_mask) == 0) {
+      return static_cast<other_uint_type>(
+          negatable_right_shift(num_throwaway_bits, significand));
+    }
+
+    bool round_away_from_zero = false;
+    // We actually have to narrow the significand here, so we have to follow the
+    // rounding rules.
+    switch (dir) {
+      case kRoundToZero:
+        break;
+      case kRoundToPositiveInfinity:
+        round_away_from_zero = !isNegative();
+        break;
+      case kRoundToNegativeInfinity:
+        round_away_from_zero = isNegative();
+        break;
+      case kRoundToNearestEven:
+        // Have to round down, round bit is 0
+        if ((first_rounded_bit & significand) == 0) {
+          break;
+        }
+        if (((significand & throwaway_mask) & ~first_rounded_bit) != 0) {
+          // If any subsequent bit of the rounded portion is non-0 then we round
+          // up.
+          round_away_from_zero = true;
+          break;
+        }
+        // We are exactly half-way between 2 numbers, pick even.
+        if ((significand & last_significant_bit) != 0) {
+          // 1 for our last bit, round up.
+          round_away_from_zero = true;
+          break;
+        }
+        break;
+    }
+
+    if (round_away_from_zero) {
+      return static_cast<other_uint_type>(
+          negatable_right_shift(num_throwaway_bits, incrementSignificand(
+              significand, last_significant_bit, carry_bit)));
+    } else {
+      return static_cast<other_uint_type>(
+          negatable_right_shift(num_throwaway_bits, significand));
+    }
+  }
+
+  // Casts this value to another HexFloat. If the cast is widening,
+  // then round_dir is ignored. If the cast is narrowing, then
+  // the result is rounded in the direction specified.
+  // This number will retain Nan and Inf values.
+  // It will also saturate to Inf if the number overflows, and
+  // underflow to (0 or min depending on rounding) if the number underflows.
+  template <typename other_T>
+  void castTo(other_T& other, round_direction round_dir) {
+    other = other_T(static_cast<typename other_T::native_type>(0));
+    bool negate = isNegative();
+    if (getUnsignedBits() == 0) {
+      if (negate) {
+        other.set_value(-other.value());
+      }
+      return;
+    }
+    uint_type significand = getSignificandBits();
+    bool carried = false;
+    typename other_T::uint_type rounded_significand =
+        getRoundedNormalizedSignificand<other_T>(round_dir, &carried);
+
+    int_type exponent = getUnbiasedExponent();
+    if (exponent == min_exponent) {
+      // If we are denormal, normalize the exponent, so that we can encode
+      // easily.
+      exponent = static_cast<int_type>(exponent + 1);
+      for (uint_type check_bit = first_exponent_bit >> 1; check_bit != 0;
+           check_bit = static_cast<uint_type>(check_bit >> 1)) {
+        exponent = static_cast<int_type>(exponent - 1);
+        if (check_bit & significand) break;
+      }
+    }
+
+    bool is_nan =
+        (getBits() & exponent_mask) == exponent_mask && significand != 0;
+    bool is_inf =
+        !is_nan &&
+        ((exponent + carried) > static_cast<int_type>(other_T::exponent_bias) ||
+         (significand == 0 && (getBits() & exponent_mask) == exponent_mask));
+
+    // If we are Nan or Inf we should pass that through.
+    if (is_inf) {
+      other.set_value(BitwiseCast<typename other_T::underlying_type>(
+          static_cast<typename other_T::uint_type>(
+              (negate ? other_T::sign_mask : 0) | other_T::exponent_mask)));
+      return;
+    }
+    if (is_nan) {
+      typename other_T::uint_type shifted_significand;
+      shifted_significand = static_cast<typename other_T::uint_type>(
+          negatable_left_shift(
+              static_cast<int_type>(other_T::num_fraction_bits) -
+              static_cast<int_type>(num_fraction_bits), significand));
+
+      // We are some sort of Nan. We try to keep the bit-pattern of the Nan
+      // as close as possible. If we had to shift off bits so we are 0, then we
+      // just set the last bit.
+      other.set_value(BitwiseCast<typename other_T::underlying_type>(
+          static_cast<typename other_T::uint_type>(
+              (negate ? other_T::sign_mask : 0) | other_T::exponent_mask |
+              (shifted_significand == 0 ? 0x1 : shifted_significand))));
+      return;
+    }
+
+    bool round_underflow_up =
+        isNegative() ? round_dir == kRoundToNegativeInfinity
+                     : round_dir == kRoundToPositiveInfinity;
+    typedef typename other_T::int_type other_int_type;
+    // setFromSignUnbiasedExponentAndNormalizedSignificand will
+    // zero out any underflowing value (but retain the sign).
+    other.setFromSignUnbiasedExponentAndNormalizedSignificand(
+        negate, static_cast<other_int_type>(exponent), rounded_significand,
+        round_underflow_up);
+    return;
+  }
+
+ private:
+  T value_;
+
+  static_assert(num_used_bits ==
+                    Traits::num_exponent_bits + Traits::num_fraction_bits + 1,
+                "The number of bits do not fit");
+  static_assert(sizeof(T) == sizeof(uint_type), "The type sizes do not match");
+};
+
+// Returns 4 bits represented by the hex character.
+inline uint8_t get_nibble_from_character(int character) {
+  const char* dec = "0123456789";
+  const char* lower = "abcdef";
+  const char* upper = "ABCDEF";
+  const char* p = nullptr;
+  if ((p = strchr(dec, character))) {
+    return static_cast<uint8_t>(p - dec);
+  } else if ((p = strchr(lower, character))) {
+    return static_cast<uint8_t>(p - lower + 0xa);
+  } else if ((p = strchr(upper, character))) {
+    return static_cast<uint8_t>(p - upper + 0xa);
+  }
+
+  assert(false && "This was called with a non-hex character");
+  return 0;
+}
+
+// Outputs the given HexFloat to the stream.
+template <typename T, typename Traits>
+std::ostream& operator<<(std::ostream& os, const HexFloat<T, Traits>& value) {
+  typedef HexFloat<T, Traits> HF;
+  typedef typename HF::uint_type uint_type;
+  typedef typename HF::int_type int_type;
+
+  static_assert(HF::num_used_bits != 0,
+                "num_used_bits must be non-zero for a valid float");
+  static_assert(HF::num_exponent_bits != 0,
+                "num_exponent_bits must be non-zero for a valid float");
+  static_assert(HF::num_fraction_bits != 0,
+                "num_fractin_bits must be non-zero for a valid float");
+
+  const uint_type bits = spvutils::BitwiseCast<uint_type>(value.value());
+  const char* const sign = (bits & HF::sign_mask) ? "-" : "";
+  const uint_type exponent = static_cast<uint_type>(
+      (bits & HF::exponent_mask) >> HF::num_fraction_bits);
+
+  uint_type fraction = static_cast<uint_type>((bits & HF::fraction_encode_mask)
+                                              << HF::num_overflow_bits);
+
+  const bool is_zero = exponent == 0 && fraction == 0;
+  const bool is_denorm = exponent == 0 && !is_zero;
+
+  // exponent contains the biased exponent we have to convert it back into
+  // the normal range.
+  int_type int_exponent = static_cast<int_type>(exponent - HF::exponent_bias);
+  // If the number is all zeros, then we actually have to NOT shift the
+  // exponent.
+  int_exponent = is_zero ? 0 : int_exponent;
+
+  // If we are denorm, then start shifting, and decreasing the exponent until
+  // our leading bit is 1.
+
+  if (is_denorm) {
+    while ((fraction & HF::fraction_top_bit) == 0) {
+      fraction = static_cast<uint_type>(fraction << 1);
+      int_exponent = static_cast<int_type>(int_exponent - 1);
+    }
+    // Since this is denormalized, we have to consume the leading 1 since it
+    // will end up being implicit.
+    fraction = static_cast<uint_type>(fraction << 1);  // eat the leading 1
+    fraction &= HF::fraction_represent_mask;
+  }
+
+  uint_type fraction_nibbles = HF::fraction_nibbles;
+  // We do not have to display any trailing 0s, since this represents the
+  // fractional part.
+  while (fraction_nibbles > 0 && (fraction & 0xF) == 0) {
+    // Shift off any trailing values;
+    fraction = static_cast<uint_type>(fraction >> 4);
+    --fraction_nibbles;
+  }
+
+  const auto saved_flags = os.flags();
+  const auto saved_fill = os.fill();
+
+  os << sign << "0x" << (is_zero ? '0' : '1');
+  if (fraction_nibbles) {
+    // Make sure to keep the leading 0s in place, since this is the fractional
+    // part.
+    os << "." << std::setw(static_cast<int>(fraction_nibbles))
+       << std::setfill('0') << std::hex << fraction;
+  }
+  os << "p" << std::dec << (int_exponent >= 0 ? "+" : "") << int_exponent;
+
+  os.flags(saved_flags);
+  os.fill(saved_fill);
+
+  return os;
+}
+
+// Returns true if negate_value is true and the next character on the
+// input stream is a plus or minus sign.  In that case we also set the fail bit
+// on the stream and set the value to the zero value for its type.
+template <typename T, typename Traits>
+inline bool RejectParseDueToLeadingSign(std::istream& is, bool negate_value,
+                                        HexFloat<T, Traits>& value) {
+  if (negate_value) {
+    auto next_char = is.peek();
+    if (next_char == '-' || next_char == '+') {
+      // Fail the parse.  Emulate standard behaviour by setting the value to
+      // the zero value, and set the fail bit on the stream.
+      value = HexFloat<T, Traits>(typename HexFloat<T, Traits>::uint_type(0));
+      is.setstate(std::ios_base::failbit);
+      return true;
+    }
+  }
+  return false;
+}
+
+// Parses a floating point number from the given stream and stores it into the
+// value parameter.
+// If negate_value is true then the number may not have a leading minus or
+// plus, and if it successfully parses, then the number is negated before
+// being stored into the value parameter.
+// If the value cannot be correctly parsed or overflows the target floating
+// point type, then set the fail bit on the stream.
+// TODO(dneto): Promise C++11 standard behavior in how the value is set in
+// the error case, but only after all target platforms implement it correctly.
+// In particular, the Microsoft C++ runtime appears to be out of spec.
+template <typename T, typename Traits>
+inline std::istream& ParseNormalFloat(std::istream& is, bool negate_value,
+                                      HexFloat<T, Traits>& value) {
+  if (RejectParseDueToLeadingSign(is, negate_value, value)) {
+    return is;
+  }
+  T val;
+  is >> val;
+  if (negate_value) {
+    val = -val;
+  }
+  value.set_value(val);
+  // In the failure case, map -0.0 to 0.0.
+  if (is.fail() && value.getUnsignedBits() == 0u) {
+    value = HexFloat<T, Traits>(typename HexFloat<T, Traits>::uint_type(0));
+  }
+  if (val.isInfinity()) {
+    // Fail the parse.  Emulate standard behaviour by setting the value to
+    // the closest normal value, and set the fail bit on the stream.
+    value.set_value((value.isNegative() | negate_value) ? T::lowest()
+                                                        : T::max());
+    is.setstate(std::ios_base::failbit);
+  }
+  return is;
+}
+
+// Specialization of ParseNormalFloat for FloatProxy<Float16> values.
+// This will parse the float as it were a 32-bit floating point number,
+// and then round it down to fit into a Float16 value.
+// The number is rounded towards zero.
+// If negate_value is true then the number may not have a leading minus or
+// plus, and if it successfully parses, then the number is negated before
+// being stored into the value parameter.
+// If the value cannot be correctly parsed or overflows the target floating
+// point type, then set the fail bit on the stream.
+// TODO(dneto): Promise C++11 standard behavior in how the value is set in
+// the error case, but only after all target platforms implement it correctly.
+// In particular, the Microsoft C++ runtime appears to be out of spec.
+template <>
+inline std::istream&
+ParseNormalFloat<FloatProxy<Float16>, HexFloatTraits<FloatProxy<Float16>>>(
+    std::istream& is, bool negate_value,
+    HexFloat<FloatProxy<Float16>, HexFloatTraits<FloatProxy<Float16>>>& value) {
+  // First parse as a 32-bit float.
+  HexFloat<FloatProxy<float>> float_val(0.0f);
+  ParseNormalFloat(is, negate_value, float_val);
+
+  // Then convert to 16-bit float, saturating at infinities, and
+  // rounding toward zero.
+  float_val.castTo(value, kRoundToZero);
+
+  // Overflow on 16-bit behaves the same as for 32- and 64-bit: set the
+  // fail bit and set the lowest or highest value.
+  if (Float16::isInfinity(value.value().getAsFloat())) {
+    value.set_value(value.isNegative() ? Float16::lowest() : Float16::max());
+    is.setstate(std::ios_base::failbit);
+  }
+  return is;
+}
+
+// Reads a HexFloat from the given stream.
+// If the float is not encoded as a hex-float then it will be parsed
+// as a regular float.
+// This may fail if your stream does not support at least one unget.
+// Nan values can be encoded with "0x1.<not zero>p+exponent_bias".
+// This would normally overflow a float and round to
+// infinity but this special pattern is the exact representation for a NaN,
+// and therefore is actually encoded as the correct NaN. To encode inf,
+// either 0x0p+exponent_bias can be specified or any exponent greater than
+// exponent_bias.
+// Examples using IEEE 32-bit float encoding.
+//    0x1.0p+128 (+inf)
+//    -0x1.0p-128 (-inf)
+//
+//    0x1.1p+128 (+Nan)
+//    -0x1.1p+128 (-Nan)
+//
+//    0x1p+129 (+inf)
+//    -0x1p+129 (-inf)
+template <typename T, typename Traits>
+std::istream& operator>>(std::istream& is, HexFloat<T, Traits>& value) {
+  using HF = HexFloat<T, Traits>;
+  using uint_type = typename HF::uint_type;
+  using int_type = typename HF::int_type;
+
+  value.set_value(static_cast<typename HF::native_type>(0.f));
+
+  if (is.flags() & std::ios::skipws) {
+    // If the user wants to skip whitespace , then we should obey that.
+    while (std::isspace(is.peek())) {
+      is.get();
+    }
+  }
+
+  auto next_char = is.peek();
+  bool negate_value = false;
+
+  if (next_char != '-' && next_char != '0') {
+    return ParseNormalFloat(is, negate_value, value);
+  }
+
+  if (next_char == '-') {
+    negate_value = true;
+    is.get();
+    next_char = is.peek();
+  }
+
+  if (next_char == '0') {
+    is.get();  // We may have to unget this.
+    auto maybe_hex_start = is.peek();
+    if (maybe_hex_start != 'x' && maybe_hex_start != 'X') {
+      is.unget();
+      return ParseNormalFloat(is, negate_value, value);
+    } else {
+      is.get();  // Throw away the 'x';
+    }
+  } else {
+    return ParseNormalFloat(is, negate_value, value);
+  }
+
+  // This "looks" like a hex-float so treat it as one.
+  bool seen_p = false;
+  bool seen_dot = false;
+  uint_type fraction_index = 0;
+
+  uint_type fraction = 0;
+  int_type exponent = HF::exponent_bias;
+
+  // Strip off leading zeros so we don't have to special-case them later.
+  while ((next_char = is.peek()) == '0') {
+    is.get();
+  }
+
+  bool is_denorm =
+      true;  // Assume denorm "representation" until we hear otherwise.
+             // NB: This does not mean the value is actually denorm,
+             // it just means that it was written 0.
+  bool bits_written = false;  // Stays false until we write a bit.
+  while (!seen_p && !seen_dot) {
+    // Handle characters that are left of the fractional part.
+    if (next_char == '.') {
+      seen_dot = true;
+    } else if (next_char == 'p') {
+      seen_p = true;
+    } else if (::isxdigit(next_char)) {
+      // We know this is not denormalized since we have stripped all leading
+      // zeroes and we are not a ".".
+      is_denorm = false;
+      int number = get_nibble_from_character(next_char);
+      for (int i = 0; i < 4; ++i, number <<= 1) {
+        uint_type write_bit = (number & 0x8) ? 0x1 : 0x0;
+        if (bits_written) {
+          // If we are here the bits represented belong in the fractional
+          // part of the float, and we have to adjust the exponent accordingly.
+          fraction = static_cast<uint_type>(
+              fraction |
+              static_cast<uint_type>(
+                  write_bit << (HF::top_bit_left_shift - fraction_index++)));
+          exponent = static_cast<int_type>(exponent + 1);
+        }
+        bits_written |= write_bit != 0;
+      }
+    } else {
+      // We have not found our exponent yet, so we have to fail.
+      is.setstate(std::ios::failbit);
+      return is;
+    }
+    is.get();
+    next_char = is.peek();
+  }
+  bits_written = false;
+  while (seen_dot && !seen_p) {
+    // Handle only fractional parts now.
+    if (next_char == 'p') {
+      seen_p = true;
+    } else if (::isxdigit(next_char)) {
+      int number = get_nibble_from_character(next_char);
+      for (int i = 0; i < 4; ++i, number <<= 1) {
+        uint_type write_bit = (number & 0x8) ? 0x01 : 0x00;
+        bits_written |= write_bit != 0;
+        if (is_denorm && !bits_written) {
+          // Handle modifying the exponent here this way we can handle
+          // an arbitrary number of hex values without overflowing our
+          // integer.
+          exponent = static_cast<int_type>(exponent - 1);
+        } else {
+          fraction = static_cast<uint_type>(
+              fraction |
+              static_cast<uint_type>(
+                  write_bit << (HF::top_bit_left_shift - fraction_index++)));
+        }
+      }
+    } else {
+      // We still have not found our 'p' exponent yet, so this is not a valid
+      // hex-float.
+      is.setstate(std::ios::failbit);
+      return is;
+    }
+    is.get();
+    next_char = is.peek();
+  }
+
+  bool seen_sign = false;
+  int8_t exponent_sign = 1;
+  int_type written_exponent = 0;
+  while (true) {
+    if ((next_char == '-' || next_char == '+')) {
+      if (seen_sign) {
+        is.setstate(std::ios::failbit);
+        return is;
+      }
+      seen_sign = true;
+      exponent_sign = (next_char == '-') ? -1 : 1;
+    } else if (::isdigit(next_char)) {
+      // Hex-floats express their exponent as decimal.
+      written_exponent = static_cast<int_type>(written_exponent * 10);
+      written_exponent =
+          static_cast<int_type>(written_exponent + (next_char - '0'));
+    } else {
+      break;
+    }
+    is.get();
+    next_char = is.peek();
+  }
+
+  written_exponent = static_cast<int_type>(written_exponent * exponent_sign);
+  exponent = static_cast<int_type>(exponent + written_exponent);
+
+  bool is_zero = is_denorm && (fraction == 0);
+  if (is_denorm && !is_zero) {
+    fraction = static_cast<uint_type>(fraction << 1);
+    exponent = static_cast<int_type>(exponent - 1);
+  } else if (is_zero) {
+    exponent = 0;
+  }
+
+  if (exponent <= 0 && !is_zero) {
+    fraction = static_cast<uint_type>(fraction >> 1);
+    fraction |= static_cast<uint_type>(1) << HF::top_bit_left_shift;
+  }
+
+  fraction = (fraction >> HF::fraction_right_shift) & HF::fraction_encode_mask;
+
+  const int_type max_exponent =
+      SetBits<uint_type, 0, HF::num_exponent_bits>::get;
+
+  // Handle actual denorm numbers
+  while (exponent < 0 && !is_zero) {
+    fraction = static_cast<uint_type>(fraction >> 1);
+    exponent = static_cast<int_type>(exponent + 1);
+
+    fraction &= HF::fraction_encode_mask;
+    if (fraction == 0) {
+      // We have underflowed our fraction. We should clamp to zero.
+      is_zero = true;
+      exponent = 0;
+    }
+  }
+
+  // We have overflowed so we should be inf/-inf.
+  if (exponent > max_exponent) {
+    exponent = max_exponent;
+    fraction = 0;
+  }
+
+  uint_type output_bits = static_cast<uint_type>(
+      static_cast<uint_type>(negate_value ? 1 : 0) << HF::top_bit_left_shift);
+  output_bits |= fraction;
+
+  uint_type shifted_exponent = static_cast<uint_type>(
+      static_cast<uint_type>(exponent << HF::exponent_left_shift) &
+      HF::exponent_mask);
+  output_bits |= shifted_exponent;
+
+  T output_float = spvutils::BitwiseCast<T>(output_bits);
+  value.set_value(output_float);
+
+  return is;
+}
+
+// Writes a FloatProxy value to a stream.
+// Zero and normal numbers are printed in the usual notation, but with
+// enough digits to fully reproduce the value.  Other values (subnormal,
+// NaN, and infinity) are printed as a hex float.
+template <typename T>
+std::ostream& operator<<(std::ostream& os, const FloatProxy<T>& value) {
+  auto float_val = value.getAsFloat();
+  switch (std::fpclassify(float_val)) {
+    case FP_ZERO:
+    case FP_NORMAL: {
+      auto saved_precision = os.precision();
+      os.precision(std::numeric_limits<T>::digits10);
+      os << float_val;
+      os.precision(saved_precision);
+    } break;
+    default:
+      os << HexFloat<FloatProxy<T>>(value);
+      break;
+  }
+  return os;
+}
+
+template <>
+inline std::ostream& operator<<<Float16>(std::ostream& os,
+                                         const FloatProxy<Float16>& value) {
+  os << HexFloat<FloatProxy<Float16>>(value);
+  return os;
+}
+}
+
+#endif  // LIBSPIRV_UTIL_HEX_FLOAT_H_