How to rebase each element of an array?

[John-K]

Hey folks, I have data that looks like:

Hex View  00 01 02 03 04 05 06 07  08 09 0A 0B 0C 0D 0E 0F
00000040  04 00 00 00 01 00 00 00  02 00 00 00 03 00 00 00  ................
00000050  04 00 00 00 FF FF FF FF  FF FF FF FF FF FF FF FF  ................

Where it gives the number of elements (4) and the block indexes of each of the elements. Specifying a pointer_base function for the array, only rebases based on the 0th element and not for each subsequent one.

struct group_table {
    u32 num_groups;
    // invalid syntax
/*
    group * groups[
    for (u32 i = 0; i < num_groups; i++) {
        std::mem::read_unsigned($,4) * 512;
    }];
*/
    // below only applies pointer_base to the 0th element and is not re-applied for each other element (0th offset is applied to each instead)
    group *groups[num_groups] : u32 [[pointer_base("block_to_byte_offset")]];
};

How can I read in the N pointers, apply the transform (* 512 in this case) and then capture that in the array?

I tried creating a new array using for inside of the array brackets like how while is shown in the documentation, but this isn't valid.

This is a trivial example, there are more complex structs that need the same treatment in this file.

[paxcut]

To create an array of pointers:

/**** First create a struct to represent a pointer ****/
struct Ptr {
   group *groups :  u32 [[pointer_base("block_to_byte_offset")]];
};
/****** Then you can create arrays of them inside other patterns ****/
struct ArrayOfPtrs {
   Ptr ptrs[num_groups];
};

ArrayOfPtrs array@0;


/*******  Or simply create and place the array ******/
Ptr ptrs[num_groups]@0;

what you are creating in your code is a pointer to an array, not an array of pointers

[John-K]

Aha, this makes sense. I will try it

…

On Thu, Jan 30, 2025 at 9:14 PM paxcut ***@***.***> wrote: To create an array of pointers: /**** First create a struct to represent a pointer ****/struct Ptr { group *groups : u32 [[pointer_base("block_to_byte_offset")]]; };/****** Then you can create arrays of them inside other patterns ****/struct ArrayOfPtrs { Ptr ptrs[num_groups]; }; ArrayOfPtrs ***@***.***; /******* Or simply create and place the array ******/Ptr ***@***.***; what you are creating in your code is a pointer to an array, not an array of pointers — Reply to this email directly, view it on GitHub <#2097 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AADCSVRY3OFHICHDG23JOX32NLMBZAVCNFSM6AAAAABWGSSQQ6VHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTEMBRGMZTEMI> . You are receiving this because you authored the thread.Message ID: ***@***.***>