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NBT: implement the integer helper functions

BodgeMaster-unfinished
BodgeMaster 2022-06-28 22:04:04 +02:00
parent 12b4a8bb55
commit 7c12a92b2a
2 changed files with 33 additions and 35 deletions
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59
src/lib/nbt.cpp
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@ -21,46 +21,53 @@
#include "error.h++"
// This is just an example for how to find out if the system is big endian
// or little endian. Do not use this.
int endianness_example() {
if constexpr (std::endian::native == std::endian::big)
{
// Big-endian system
return 0;
}
else if constexpr (std::endian::native == std::endian::little)
{
// Little-endian system
return 1;
}
else
{
// Something else
return 2;
// How did we even end up here?
}
}
// or little endian.
//int endianness_example() {
// if constexpr (std::endian::native == std::endian::big)
// {
// // Big-endian system
// return 0;
// }
// else if constexpr (std::endian::native == std::endian::little)
// {
// // Little-endian system
// return 1;
// }
// else
// {
// // Something else
// return 2;
// // How did we even end up here?
// }
//}
// There is supposedly also a function htobe64 and be64toh to deal with
// converting 64 bit integers between host order and big endian.
// Though converting between host order and BE may not be necessary if the
// raw NBT data is to be used as instructions for rebuilding the data in memory.
// Doing the opposite may just be very painful.
namespace NBT {
namespace helper {
ErrorOr<int8_t> readInt8(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
if (dataSize<=currentPosition) return ErrorOr<int8_t>(true, ErrorCodes::RANGE_ERROR);
if (dataSize<currentPosition+1) return ErrorOr<int8_t>(true, ErrorCodes::RANGE_ERROR);
return ErrorOr<int8_t>((int8_t) data[currentPosition]);
}
ErrorOr<int16_t> readInt16(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
//TODO: implement
return ErrorOr<int16_t>((int16_t) 0);
if (dataSize<currentPosition+2) return ErrorOr<int16_t>(true, ErrorCodes::RANGE_ERROR);
return ErrorOr<int16_t>((int16_t) ((static_cast<int16_t>(data[currentPosition]) << 8) | static_cast<int16_t>(data[currentPosition+1])));
}
ErrorOr<int32_t> readInt32(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
//TODO: implement
return ErrorOr<int32_t>((int32_t) 0);
if (dataSize<currentPosition+4) return ErrorOr<int32_t>(true, ErrorCodes::RANGE_ERROR);
return ErrorOr<int32_t>((int32_t) ((static_cast<int32_t>(data[currentPosition]) << 24) | (static_cast<int32_t>(data[currentPosition+1]) << 16) | (static_cast<int32_t>(data[currentPosition+2]) << 8) | static_cast<int32_t>(data[currentPosition+3])));
}
ErrorOr<int64_t> readInt64(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
//TODO: implement
return ErrorOr<int64_t>((int64_t) 0);
if (dataSize<currentPosition+8) return ErrorOr<int64_t>(true, ErrorCodes::RANGE_ERROR);
return ErrorOr<int64_t>((int64_t) ((static_cast<int64_t>(data[currentPosition]) << 56) | (static_cast<int64_t>(data[currentPosition+1]) << 48) | (static_cast<int64_t>(data[currentPosition+2]) << 40) | (static_cast<int64_t>(data[currentPosition+3]) << 32) | (static_cast<int64_t>(data[currentPosition]) << 24) | (static_cast<int64_t>(data[currentPosition+1]) << 16) | (static_cast<int64_t>(data[currentPosition+2]) << 8) | static_cast<int64_t>(data[currentPosition+3])));
}
//FIXME: we just assume that float is a single-precision IEEE754

9
src/lib/nbt.h++
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@ -42,27 +42,18 @@
namespace NBT {
namespace helper {
ErrorOr<int8_t> readInt8(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
ErrorOr<int16_t> readInt16(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
ErrorOr<int32_t> readInt32(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
ErrorOr<int64_t> readInt64(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
//FIXME: we just assume that float is a single-precision IEEE754
// floating point number
ErrorOr<float> readFloat32(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
//FIXME: we just assume that double is a double-precision IEEE754
// floating point number
ErrorOr<double> readFloat64(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
ErrorOr<std::vector<int8_t>> readInt8Array(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
//ErrorOr<> readString(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
ErrorOr<std::vector<int32_t>> readInt32Array(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
ErrorOr<std::vector<int64_t>> readInt64Array(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
}