BitConverter.h

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#pragma once
 
#include <cstdint>
#include <limits>
#include <vector>
#include <cstring>
 
#ifdef _MSC_VER
#define BSWAP16 _byteswap_ushort 
#define BSWAP32 _byteswap_ulong  
#define BSWAP64 _byteswap_uint64 
#else
#define BSWAP16 __builtin_bswap16 
#define BSWAP32 __builtin_bswap32 
#define BSWAP64 __builtin_bswap64 
#endif
 
enum class Endianness {
    Little = 0, 
    Big = 1,    
 
#if (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)) || defined(__BIG_ENDIAN__)
    Native = Big, 
#else
    Native = Little, 
#endif
};
 
class BitConverter {
  public:
    static inline int8_t ToInt8BE(const uint8_t* data, int32_t offset) {
        return (uint8_t)data[offset + 0];
    }
 
    static inline int8_t ToInt8BE(const std::vector<uint8_t>& data, int32_t offset) {
        return (uint8_t)data[offset + 0];
    }
 
    static inline uint8_t ToUInt8BE(const uint8_t* data, int32_t offset) {
        return (uint8_t)data[offset + 0];
    }
 
    static inline uint8_t ToUInt8BE(const std::vector<uint8_t>& data, int32_t offset) {
        return (uint8_t)data[offset + 0];
    }
 
    static inline int16_t ToInt16BE(const uint8_t* data, int32_t offset) {
        return ((uint16_t)data[offset + 0] << 8) + (uint16_t)data[offset + 1];
    }
 
    static inline int16_t ToInt16BE(const std::vector<uint8_t>& data, int32_t offset) {
        return ((uint16_t)data[offset + 0] << 8) + (uint16_t)data[offset + 1];
    }
 
    static inline uint16_t ToUInt16BE(const uint8_t* data, int32_t offset) {
        return ((uint16_t)data[offset + 0] << 8) + (uint16_t)data[offset + 1];
    }
 
    static inline uint16_t ToUInt16BE(const std::vector<uint8_t>& data, int32_t offset) {
        return ((uint16_t)data[offset + 0] << 8) + (uint16_t)data[offset + 1];
    }
 
    static inline int32_t ToInt32BE(const uint8_t* data, int32_t offset) {
        return ((uint32_t)data[offset + 0] << 24) + ((uint32_t)data[offset + 1] << 16) +
               ((uint32_t)data[offset + 2] << 8) + (uint32_t)data[offset + 3];
    }
 
    static inline int32_t ToInt32BE(const std::vector<uint8_t>& data, int32_t offset) {
        return ((uint32_t)data[offset + 0] << 24) + ((uint32_t)data[offset + 1] << 16) +
               ((uint32_t)data[offset + 2] << 8) + (uint32_t)data[offset + 3];
    }
 
    static inline uint32_t ToUInt32BE(const uint8_t* data, int32_t offset) {
        return ((uint32_t)data[offset + 0] << 24) + ((uint32_t)data[offset + 1] << 16) +
               ((uint32_t)data[offset + 2] << 8) + (uint32_t)data[offset + 3];
    }
 
    static inline uint32_t ToUInt32BE(const std::vector<uint8_t>& data, int32_t offset) {
        return ((uint32_t)data[offset + 0] << 24) + ((uint32_t)data[offset + 1] << 16) +
               ((uint32_t)data[offset + 2] << 8) + (uint32_t)data[offset + 3];
    }
 
    static inline int64_t ToInt64BE(const uint8_t* data, int32_t offset) {
        return ((uint64_t)data[offset + 0] << 56) + ((uint64_t)data[offset + 1] << 48) +
               ((uint64_t)data[offset + 2] << 40) + ((uint64_t)data[offset + 3] << 32) +
               ((uint64_t)data[offset + 4] << 24) + ((uint64_t)data[offset + 5] << 16) +
               ((uint64_t)data[offset + 6] << 8) + ((uint64_t)data[offset + 7]);
    }
 
    static inline int64_t ToInt64BE(const std::vector<uint8_t>& data, int32_t offset) {
        return ((uint64_t)data[offset + 0] << 56) + ((uint64_t)data[offset + 1] << 48) +
               ((uint64_t)data[offset + 2] << 40) + ((uint64_t)data[offset + 3] << 32) +
               ((uint64_t)data[offset + 4] << 24) + ((uint64_t)data[offset + 5] << 16) +
               ((uint64_t)data[offset + 6] << 8) + ((uint64_t)data[offset + 7]);
    }
 
    static inline uint64_t ToUInt64BE(const uint8_t* data, int32_t offset) {
        return ((uint64_t)data[offset + 0] << 56) + ((uint64_t)data[offset + 1] << 48) +
               ((uint64_t)data[offset + 2] << 40) + ((uint64_t)data[offset + 3] << 32) +
               ((uint64_t)data[offset + 4] << 24) + ((uint64_t)data[offset + 5] << 16) +
               ((uint64_t)data[offset + 6] << 8) + ((uint64_t)data[offset + 7]);
    }
 
    static inline uint64_t ToUInt64BE(const std::vector<uint8_t>& data, int32_t offset) {
        return ((uint64_t)data[offset + 0] << 56) + ((uint64_t)data[offset + 1] << 48) +
               ((uint64_t)data[offset + 2] << 40) + ((uint64_t)data[offset + 3] << 32) +
               ((uint64_t)data[offset + 4] << 24) + ((uint64_t)data[offset + 5] << 16) +
               ((uint64_t)data[offset + 6] << 8) + ((uint64_t)data[offset + 7]);
    }
 
    static inline float ToFloatBE(const uint8_t* data, int32_t offset) {
        float value;
        uint32_t floatData = ((uint32_t)data[offset + 0] << 24) + ((uint32_t)data[offset + 1] << 16) +
                             ((uint32_t)data[offset + 2] << 8) + (uint32_t)data[offset + 3];
        static_assert(sizeof(uint32_t) == sizeof(float), "expected 32-bit float");
        std::memcpy(&value, &floatData, sizeof(value));
        return value;
    }
 
    static inline float ToFloatBE(const std::vector<uint8_t>& data, int32_t offset) {
        float value;
        uint32_t floatData = ((uint32_t)data[offset + 0] << 24) + ((uint32_t)data[offset + 1] << 16) +
                             ((uint32_t)data[offset + 2] << 8) + (uint32_t)data[offset + 3];
        static_assert(sizeof(uint32_t) == sizeof(float), "expected 32-bit float");
        std::memcpy(&value, &floatData, sizeof(value));
        return value;
    }
 
    static inline double ToDoubleBE(const uint8_t* data, int32_t offset) {
        double value;
        uint64_t floatData = ((uint64_t)data[offset + 0] << 56) + ((uint64_t)data[offset + 1] << 48) +
                             ((uint64_t)data[offset + 2] << 40) + ((uint64_t)data[offset + 3] << 32) +
                             ((uint64_t)data[offset + 4] << 24) + ((uint64_t)data[offset + 5] << 16) +
                             ((uint64_t)data[offset + 6] << 8) + ((uint64_t)data[offset + 7]);
        static_assert(sizeof(uint64_t) == sizeof(double), "expected 64-bit double");
        // Checks if the float format on the platform the ZAPD binary is running on supports the
        // same float format as the object file.
        static_assert(std::numeric_limits<float>::is_iec559, "expected IEC559 floats on host machine");
        std::memcpy(&value, &floatData, sizeof(value));
        return value;
    }
 
    static inline double ToDoubleBE(const std::vector<uint8_t>& data, int32_t offset) {
        double value;
        uint64_t floatData = ((uint64_t)data[offset + 0] << 56) + ((uint64_t)data[offset + 1] << 48) +
                             ((uint64_t)data[offset + 2] << 40) + ((uint64_t)data[offset + 3] << 32) +
                             ((uint64_t)data[offset + 4] << 24) + ((uint64_t)data[offset + 5] << 16) +
                             ((uint64_t)data[offset + 6] << 8) + ((uint64_t)data[offset + 7]);
        static_assert(sizeof(uint64_t) == sizeof(double), "expected 64-bit double");
        // Checks if the float format on the platform the ZAPD binary is running on supports the
        // same float format as the object file.
        static_assert(std::numeric_limits<double>::is_iec559, "expected IEC559 doubles on host machine");
        std::memcpy(&value, &floatData, sizeof(value));
        return value;
    }
 
    static inline void RomToBigEndian(uint8_t* rom, size_t romSize) {
        if (romSize <= 0) {
            return;
        }
 
        // Use the first byte to determine byte order
        uint8_t firstByte = rom[0];
 
        switch (firstByte) {
            case 0x37: // v64
                for (size_t pos = 0; pos < (romSize / 2); pos++) {
                    ((uint16_t*)rom)[pos] = ToUInt16BE(rom, pos * 2);
                }
                break;
            case 0x40: // n64
                for (size_t pos = 0; pos < (romSize / 4); pos++) {
                    ((uint32_t*)rom)[pos] = ToUInt32BE(rom, pos * 4);
                }
                break;
            case 0x80: // z64
                break; // Already BE, no need to swap
        }
    }
};