ByteArrayParser.hpp

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#pragma once
 
#include <sndfile.hh>
#include <cstddef>
#include <cstring>
 
/*
Handles the conversion of the bytearray, representing
the .wav file where the audio labels are stored, to
a state, where it can be processed by the libsndfile
library
*/
 
struct MemoryData {
    const std::byte* data;
    sf_count_t size;
    sf_count_t pos;
};
 
inline sf_count_t vio_get_filelen(void* user_data) {
    auto* mem = static_cast<MemoryData*>(user_data);
    return mem->size;
}
 
inline sf_count_t vio_seek(sf_count_t offset, int whence, void* user_data) {
    auto* mem = static_cast<MemoryData*>(user_data);
    sf_count_t newpos = mem->pos;
 
    switch (whence) {
        case SEEK_SET: newpos = offset; break;
        case SEEK_CUR: newpos += offset; break;
        case SEEK_END: newpos = mem->size + offset; break;
        default: return -1;
    }
 
    if (newpos < 0 || newpos > mem->size)
        return -1;
 
    mem->pos = newpos;
    return mem->pos;
}
 
inline sf_count_t vio_read(void* ptr, sf_count_t count, void* user_data) {
    auto* mem = static_cast<MemoryData*>(user_data);
    sf_count_t remain = mem->size - mem->pos;
    sf_count_t to_read = (count < remain ? count : remain);
 
    if (to_read > 0) {
        std::memcpy(ptr, mem->data + mem->pos, static_cast<size_t>(to_read));
        mem->pos += to_read;
    }
 
    return to_read;
}
 
inline sf_count_t vio_write(const void* /*unused*/, sf_count_t /*unused*/, void* /*unused*/) {
    return 0;
}
 
inline sf_count_t vio_tell(void* user_data) {
    auto* mem = static_cast<MemoryData*>(user_data);
    return mem->pos;
}