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 // SPDX-License-Identifier: MIT
 // Copyright (c) 2025, Advanced Micro Devices, Inc. All rights reserved.
  
 #include "ck_tile/core/config.hpp"
 #include "ck_tile/core/numeric/half.hpp"
 #include "ck_tile/core/numeric/integral_constant.hpp"
 #include "ck_tile/core/numeric/math.hpp"
 #include "ck_tile/core/numeric/numeric.hpp"
 #include "ck_tile/core/utility/bit_cast.hpp"
 #include "ck_tile/core/utility/random.hpp"
 #include <stdint.h>
 #include <type_traits>
 #include "ck_tile/core/numeric/int8.hpp"
  
 #pragma once
  
 namespace ck_tile {
  
 // Packed 2xint4
 struct pk_int4_t
 {
     using type = int8_t;
     type data;
     CK_TILE_HOST_DEVICE constexpr pk_int4_t() : data{type{}} {}
     CK_TILE_HOST_DEVICE constexpr pk_int4_t(type init) : data{init} {}
 };
  
 // limits
 template <class T>
 struct numeric;
  
 template <>
 struct numeric<pk_int4_t>
 {
     // minimum finite value, or minimum positive normalized value for float
     CK_TILE_HOST_DEVICE static constexpr pk_int4_t min()
     {
         constexpr uint8_t val = 0b10001000;
         return pk_int4_t(bit_cast<int8_t>(val));
     }
  
     // minumum finite value
     CK_TILE_HOST_DEVICE static constexpr pk_int4_t lowest()
     {
         constexpr uint8_t val = 0b10001000;
         return pk_int4_t(bit_cast<int8_t>(val));
     }
  
     // maximum finite value
     CK_TILE_HOST_DEVICE static constexpr pk_int4_t max()
     {
         constexpr uint8_t val = 0b01110111;
         return pk_int4_t(bit_cast<int8_t>(val));
     }
  
     // difference between 1.0 and next value representable by float
     CK_TILE_HOST_DEVICE static constexpr pk_int4_t epsilon()
     {
         return 1; // not used
     }
  
     CK_TILE_HOST_DEVICE static constexpr pk_int4_t round_error()
     {
         return 1; // not used
     }
  
     // positive infinity value
     CK_TILE_HOST_DEVICE static constexpr pk_int4_t infinity()
     {
         return 1; // not used
     }
  
     // quiet NaN
     CK_TILE_HOST_DEVICE static constexpr pk_int4_t quiet_NaN()
     {
         return 1; // not used
     }
  
     // signaling NaN
     CK_TILE_HOST_DEVICE static constexpr pk_int4_t signaling_NaN()
     {
         return 1; // not used
     }
  
     // smallest positive subnormal value
     CK_TILE_HOST_DEVICE static constexpr pk_int4_t denorm_min()
     {
         return 1; // not used
     }
  
     CK_TILE_HOST_DEVICE static constexpr pk_int4_t zero() { return 0; }
 };
  
 template <>
 struct numeric_traits<pk_int4_t>
 {
     static constexpr int PackedSize = 2;
 };
  
 using fp32x2_t = float __attribute__((ext_vector_type(2)));
 using fp16x2_t = _Float16 __attribute__((ext_vector_type(2)));
 using bf16x2_t = bf16_raw_t __attribute__((ext_vector_type(2)));
  
 CK_TILE_HOST_DEVICE fp32x2_t pk_int4_t_to_fp32x2_t(const pk_int4_t& x)
 {
     uint8_t x_u8 = ck_tile::bit_cast<uint8_t>(x);
  
     float x_l = ((x_u8 & 0x0f) >> 0) - 8.f;
     float x_h = ((x_u8 & 0xf0) >> 4) - 8.f;
  
 #ifdef CK_TILE_USE_PK4_LAYOUT_SHUFFLE
     fp32x2_t res = {x_h, x_l};
 #elif
     fp32x2_t res = {x_l, x_h};
 #endif
     return res;
 }
  
 CK_TILE_HOST_DEVICE fp16x2_t pk_int4_t_to_halfx2_t(const pk_int4_t& x)
 {
     uint8_t x_u8 = ck_tile::bit_cast<uint8_t>(x);
 #ifdef CK_TILE_USE_PK4_LAYOUT_SHUFFLE
     uint32_t i4s = ((x_u8 & 0x0f) << 16) | ((x_u8 & 0xf0) >> 4);
 #elif
     uint32_t i4s = ((x_u8 & 0xf0) << 12) | (x_u8 & 0xf);
 #endif
     const int EX  = 0x64006400;
     const int SUB = 0xE408E408; //-8
  
     int lo = i4s | EX;
  
     return pk_add_f16(bit_cast<fp16x2_t>(lo), bit_cast<fp16x2_t>(SUB));
 }
  
 CK_TILE_HOST_DEVICE bf16x2_t pk_int4_t_to_bfloat16x2_t(const pk_int4_t& x)
 {
     uint8_t x_u8 = ck_tile::bit_cast<uint8_t>(x);
  
     float x_l = ((x_u8 & 0x0f) >> 0) - 8.f;
     float x_h = ((x_u8 & 0xf0) >> 4) - 8.f;
  
 #ifdef CK_TILE_USE_PK4_LAYOUT_SHUFFLE
     bf16x2_t res = {type_convert<bf16_t>(x_h), type_convert<bf16_t>(x_l)};
 #elif
     bf16x2_t res = {type_convert<bf16_t>(x_l), type_convert<bf16_t>(x_h)};
 #endif
     return res;
 }
  
 } // namespace ck_tile