Fix build warnings

[noctonca]

Based on the build output the build currently has 29 warnings that we should clean up.

• cast to pointer from integer of different size
• passing NULL to non-pointer argument
• format-truncation (snprintf)
• converting to non-pointer type from NULL
• overflow in conversion
• initialized and declared extern

The most common issue is pointer/integer size mismatch (22 warnings) — these occur because the code was originally written for 32-bit systems where int and pointers were the same size. On 64-bit systems, pointers are 8 bytes while int/U32 are 4 bytes, causing these warnings when casting between them.

[noctonca]

Once ASM validation is done we will look at this