Variable number of structures

[s5rockhoppers]

I have a question about how to parse a certain type of file. The file is structured list this:

Top level

• general info
• instrument info
• pitch tables (1-8)
• • pitch table pointers
• layers (1-8)
• • layer pointers
• samples (1-127)
• • sample pointers
• data pointed to by pointers above
• ......

Each of the sections above is a contains pointers to where the data actually is in the file. So, for example, layer1 would contain a pointer to where the layer data was in the file. Some of the pointers will be 0 if that layer/sample isn't used.

So I don't understand how to loop through these to get the data. I can get all the pointers, but how do I use these to go pick off the data for each layer/sample and display it in the pattern data window?

[WerWolv]

Generally all sorts of loops are implemented using arrays. If you need access to the current index, use std::core::array_index()

[ExcaliburZero]

I ran into a similar case where I was trying to parse a file that packaged together multiple files. The package file started with a header that listed each file's name, offset, and size, then stored the contents of each file after the header.

I was able to encode each file as a struct, where the struct had some it its data in the header, but was able to reference the contents of the file later down in the package file.

struct file {
    u8 name_info[0x20];
    u32 offset;
    u32 size;
    // \/ This is the important line
    u8 data[size] @ offset;
};

struct fpk {
    u32 magic;
    u32 num_files;
    file files[num_files];  
};

fpk fpk @ 0x0;

In your case, since some entries may not have data, you could try something like this:

struct file {
    u8 name_info[0x20];
    u32 offset;
    u32 size;
    // \/ These are the important lines
    if (offset != 0x0)
        u8 data[size] @ offset;
};

struct fpk {
    u32 magic;
    u32 num_files;
    file files[num_files];  
};

fpk fpk @ 0x0;