Rust Macro

Rust macro is an interesting topic and it provides a way to generate code on the fly. One of the problem for Rust programmer is the code is not easy to understand, especially for compiler and low level programming. 

The code is located at ttliu2000/rust_macro: Rust macro project to make rust programming easier. which making my assembler / linker project code simpler. My background is C# and I will keep everything private and use accessor methods to access the code, which is heavy boilerplate code. Using the macro make the code more readable. 

Thanks to ChatGPT's help, I quickly start the project and get the feature in. So if you start to create macro, ask GPT first. 

Tao's Fragments: RiscV Linux lib ELF Generation

Today is Jan 1st, 2026. And I will be back with what is meaningful. Years ago, I decide to start a new journey. After working on Rust, Linux OS, ELF file format, RiscV chip/ABI, and assembler and linker, and started C language compiler. Let's see how compiler tech and latest AI can change how technology can make programmer's life easier. 

I feel I can start blog again and share some fragments of my work and ready for open source. 

I've done the ELF executable with dynamic link support, it means that I can use my assembler+linker to generate ELF binary to invoke printf in libc. I've to say the RISCV's PLT/GOT RELA is really a headache, which can be topic for another fragemnt of mine. 😉

Today I finished the .so file generation and it can generate a library can be linked with gcc. Now I know why F# choose to support library after executable is done. And I know why F# library has its own printf. But anyway. 

The .so ELF generation is simple, my test .s file is listed below. Please note that i added my own pseudo instruction for RiscV assembly language. 

.data

.extern printf

tt_fmt: .string "%d\n"

const_float_or_string_value_104:

.string "Array index access test, expected value 42 and actual value: %d\n"

.text 

    .globl  add2               

    .type   add2, @function

add2:

    add     a0, a0, a1

    ret

    .size   add2, .-add2

    exit 42

The .extern will trigger dynamic symbol structure generation. The key here is the add2 function related instruction which is in bold font. 

• globl add2 is to add "add2" to the dynamic symbol (.dynsym) table.
• add2 shows the starting point of add2 function and it will be used to compute the size of the add2 function. 
• .size show the add2's size is equal to current (the small dot) minus add2. 

After these info being added to dynamic symbol table, the readelf -a shows the following:

the riscv64 gcc link can link this shared library with c code and command is listed below:

#include <stdio.h>

int add2(int a, int b);

int main() {

    printf("%d\n", add2(20, 22));

    return 0;

} 

and the exeuction result shows 42 which is 20 + 22 from add2(20, 22). 

Thanks to ChatGPT's which helps me to generate Linux command. Being a long time windows guy, I am still struggle to use correct Linux language, but let's see if this can change when I add more feature.