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17357d4672
| Author | SHA1 | Date | |
|---|---|---|---|
| 17357d4672 | |||
| 5644d377de | |||
| 44d2271972 |
101
src/dat/nbt.c
101
src/dat/nbt.c
@@ -98,48 +98,64 @@ const u8 *nbt_nexttag(const u8 *restrict buf) {
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return tag;
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}
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/* processes an array at `buf`, of `nmem` items with a size of `size`
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* returns a malloc'd pointer (which may be `NULL`) to the data.
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* the data is converted from big endian to little endian on little endian systems. */
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MALLOC static void *nbt_procarr(const u8 *restrict buf, i32 nmem, uint size) {
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struct nbt_array *ptr = malloc(sizeof(struct nbt_array) + nmem * size);
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if (!ptr) return NULL;
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memcpy(ptr->dat, buf, nmem * size);
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/* Processes the incoming array data in `buf`. Which contains `nmem` items of `size`.
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* The data shall be converted to little-endian on little-endian systems
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* Outputs the allocated data to `out`, returns where the next pointer would be. */
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static const u8 *procarr(const u8 *restrict buf, i32 nmem, uint size, struct nbt_array *restrict *restrict out) {
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size_t len = nmem * size;
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*out = malloc(sizeof(struct nbt_array) + len);
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if (!*out) return buf + len;
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memcpy((*out)->dat, buf, len);
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(*out)->len = nmem;
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buf += len;
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/* Only include this code for little-endian systems. Since only they require this logic.
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* Producing optimised code for other platforms. */
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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if (size == 1) return ptr;
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ssize_t i = 0;
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while (i < nmem) {
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if (size == 1) return buf;
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size_t i = 0;
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while (i < len) {
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switch (size) {
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case 2: *(u16 *)(ptr->dat + i) = be16toh(*(u16 *)(ptr->dat + i)); break;
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case 4: *(u32 *)(ptr->dat + i) = be32toh(*(u32 *)(ptr->dat + i)); break;
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case 8: *(u64 *)(ptr->dat + i) = be64toh(*(u64 *)(ptr->dat + i)); break;
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case 2: *(u16 *)((*out)->dat + i) = be16toh(*(u16 *)((*out)->dat + i)); break;
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case 4: *(u32 *)((*out)->dat + i) = be32toh(*(u32 *)((*out)->dat + i)); break;
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case 8: *(u64 *)((*out)->dat + i) = be64toh(*(u64 *)((*out)->dat + i)); break;
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default: __builtin_unreachable(); // this should be impossible
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}
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i += size;
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}
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#endif
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return ptr;
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return buf;
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}
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/* processes a `NBT_LIST` tag, and returns a pointer to malloc'd data, or `NULL`, depending on its success */
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MALLOC static void *nbt_proclist(const u8 *restrict buf) {
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/* calls `procarr` for the simple types available. */
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static const u8 *proclist(const u8 *restrict buf, struct nbt_array *restrict *restrict out) {
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uint size;
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*out = NULL;
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switch (*buf) {
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case NBT_I8: return nbt_procarr(buf + 5, (i32)be32toh(*(u32 *)buf + 1), 1);
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case NBT_I16: return nbt_procarr(buf + 5, (i32)be32toh(*(u32 *)buf + 1), 2);
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case NBT_I8: size = 1; break;
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case NBT_I16: size = 2; break;
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case NBT_I32: // fall through
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case NBT_F32: return nbt_procarr(buf + 5, (i32)be32toh(*(u32 *)buf + 1), 4);
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case NBT_F32: size = 4; break;
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case NBT_I64: // fall though
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case NBT_F64: return nbt_procarr(buf + 5, (i32)be32toh(*(u32 *)buf + 1), 8);
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case NBT_F64: size = 8; break;
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default: return NULL;
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}
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buf++;
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i32 len = (i32)be32toh(*(u32 *)buf);
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buf += 4;
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return procarr(buf, len, size, out);
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}
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/* readies the output data for export, returns the new buffer position, or `NULL` upon an error (may be out of bounds) */
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const u8 *nbt_proctag(const u8 *restrict buf, u16 slen, void *restrict out) {
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const u8 *ptr = buf + 3 + slen;
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const u8 *ptr, *tmp;
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ptr = buf + 3 + slen;
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i32 nmem;
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uint size;
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switch (*buf) {
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case NBT_I8: *(u8 *)out = *ptr; return ptr + 1;
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@@ -149,38 +165,17 @@ const u8 *nbt_proctag(const u8 *restrict buf, u16 slen, void *restrict out) {
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case NBT_I64: // fall through
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case NBT_F64: *(u64 *)out = be16toh(*(u64 *)ptr); return ptr + 8;
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case NBT_STR: *(void **)out = nbt_procarr(ptr += 2, be16toh(*(u16 *)buf), 1); break;
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case NBT_ARR_I8: *(void **)out = nbt_procarr(ptr += 4, be32toh(*(u32 *)buf), 1); break;
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case NBT_ARR_I32: *(void **)out = nbt_procarr(ptr += 4, be32toh(*(u32 *)buf), 4); break;
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case NBT_ARR_I64: *(void **)out = nbt_procarr(ptr += 8, be32toh(*(u64 *)buf), 8); break;
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case NBT_LIST: *(void **)out = nbt_proclist(ptr);
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case NBT_STR: nmem = be16toh(*(u16 *)ptr), size = 1, ptr += 2; break;
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case NBT_ARR_I8: nmem = be32toh(*(u32 *)ptr), size = 1, ptr += 4; break;
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case NBT_ARR_I32: nmem = be32toh(*(u32 *)ptr), size = 4, ptr += 4; break;
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case NBT_ARR_I64: nmem = be32toh(*(u32 *)ptr), size = 8, ptr += 4; break;
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default:
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return NULL;
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case NBT_LIST:
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return proclist(ptr, (struct nbt_array **)out);
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return tmp;
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default: return NULL;
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}
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return ptr;
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}
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struct nbt_procdat nbt_initproc(struct nbt_path const *restrict pats, uint npats) {
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i16 mdpt = 0;
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// acquire the maximum depth that we'll need to go (exclusive)
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for (uint i = 0; i < npats; i++) {
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int tmp = pats[i].len - mdpt;
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mdpt += -(tmp > 0) & tmp;
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}
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assert(mdpt > 0);
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// storing the segments of the current path
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const char **cpat = (const char **)calloc(mdpt - 1, sizeof(void *));
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// return the initialised structure.
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return (struct nbt_procdat){
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pats,
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cpat,
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npats,
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0,
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mdpt,
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};
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return procarr(ptr, nmem, size, (struct nbt_array **)out);
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}
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@@ -36,20 +36,6 @@ enum nbt_tagid {
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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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/* TODO: write doc */
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struct nbt_path {
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const char **restrict pat; // specifies the NBT path components as separate elements
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i16 len; // specifies the length of the NBT elements
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};
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/* TODO: write doc */
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struct nbt_procdat {
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const struct nbt_path *pats;
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const char *restrict *cpat;
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u32 npats;
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i16 dpt, mdpt;
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};
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struct nbt_array {
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i32 len;
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u8 dat[];
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@@ -59,15 +45,11 @@ struct nbt_array {
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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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/* Processes the tag entered in `buf`, `buf` is assumed to be the start of a named tag. Where `slen` shall be the string length.
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* The data in `buf` is processed and outputted to `out`. A pointer to the next tag, or `NULL` is returned.
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* On little-endian systems, the data is processed from big-endian to little-endian. So it can be used like normal.
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* - In the case for all basic types, `out` will require to be the width of said type.
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* - In the case of arrays (and lists), a malloc'd pointer shall be written to `out`, pointing to `struct nbt_array`. This might be `NULL`
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* - In the case of lists, the above is valid, as long as the list contains any of the following types:
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* `NBT_I8`, `NBT_I16`, `NBT_I32`, `NBT_I64`, `NBT_F32` or `NBT_F64`. Anything else will result in a `NULL` pointer.
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* Upon failure, like the tag not being able to be processed, `NULL` is returned. */
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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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/* initialises a data structure used whilst processing the tags */
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struct nbt_procdat nbt_initproc(struct nbt_path const *restrict pats, uint npats) NONNULL((1)) PURE;
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