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https://github.com/thepigeongenerator/mcaselector-lite.git
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58 lines
2.8 KiB
C
58 lines
2.8 KiB
C
/* Copyright (c) 2025 Quinn.
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* This is a file from the project MCA-Selector-Lite and is
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* licensed under the MIT Licence. See the project's LICENSE file for details. */
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#pragma once
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#include <assert.h>
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#include <endian.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include "../types.h"
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#include "../util/atrb.h"
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/* NBT (named binary tag) is a tree data structure. Tags have a numeric type ID, name and a payload.
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* NBT files are a compressed `compound` tag. GZip is the compression used in most cases,
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* in some (rare) cases it's stored uncompressed.
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* A tag is an individual part of the data tree.
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* The first byte is the ID, followed by a `u16`, for the length of the name.
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* Then the name as `UTF-8`. (end tag does not contain name) */
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/* specifies the NBT tag IDs.
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* NOTE: every type is stored as BE (big-endian) in the file. */
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enum nbt_tagid {
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NBT_END = 0x00, // signifies the end of a compound tag
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NBT_I8 = 0x01, // next byte is for an 8 bit signed integer.
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NBT_I16 = 0x02, // next 2 bytes are for a 16 bit signed integer
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NBT_I32 = 0x03, // next 4 bytes are for a 32 bit signed integer
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NBT_I64 = 0x04, // next 8 bytes are for a 64 bit signed integer
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NBT_F32 = 0x05, // next 4 bytes are for a single-precision floating-point
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NBT_F64 = 0x06, // next 8 bytes are for a double-precision floating-point
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NBT_ARR_I8 = 0x07, // starts with a i32, denoting size, followed by the i8 data
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NBT_STR = 0x08, // starts with a u16, denoting size, followed by the UTF-8 data
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NBT_LIST = 0x09, // starts with an ID, followed by a 32 bit signed integer denoting the size
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NBT_COMPOUND = 0x0A, // compound tag, contains tags and is delimited by `NBT_END`
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NBT_ARR_I32 = 0x0B, // starts with a i32, denoting size, followed by the i32 data
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NBT_ARR_I64 = 0x0C, // starts with a i32, denoting size, followed by the u32 data
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};
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struct nbt_array {
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i32 nmemb;
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void *dat;
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};
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/* Acquires the data contained by the named tag.
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* - `buf` points to the start of the tag.
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* - `slen` contains the string length of the name.
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* - `out` points to where the data should be written.
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* if `buf` points to `NBT_I8`, `NBT_I16`, `NBT_I32`, `NBT_I64`, `NBT_F32`, or `NBT_F64`, `*out` is assumed
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* to have the available byte width for one of these types. In the case of `NBT_ARR*` and `NBT_LIST`
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* it must point to a `struct nbt_array*`. Where in the case of `NBT_LIST`, it must be one of the previous static-width types. */
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const u8 *nbt_proctag(const u8 *restrict buf, u16 slen, void *restrict out) NONNULL((1, 3));
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/* searches for the end of a named tag without processing data, the final pointer is returned.
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* `NULL` is returned upon failure, the otherwise returned pointer is not guaranteed to be valid. */
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const u8 *nbt_nexttag(const u8 *restrict buf) NONNULL((1)) PURE;
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