#![no_std]
#![feature(linkage)]

use core::arch::global_asm;

#[cfg(target_arch = "aarch64")]
global_asm!(
    "
.globl _start
_start:
    mov x0, sp
    and sp, x0, #0xfffffffffffffff0 //align sp
    bl relibc_ld_so_start
    # TODO: aarch64
    udf #0
"
);

#[cfg(target_arch = "x86")]
global_asm!(
    "
.globl _start
_start:
    push esp
    call relibc_ld_so_start
    pop esp
    # TODO: x86
    ud2
"
);

#[cfg(target_arch = "x86_64")]
global_asm!(
    "
.globl _start
_start:
    # rsi = _start + 5
    call 2f
2:  pop rsi

    # Save original stack and align stack to 16 bytes
    mov rbp, rsp
    and rsp, 0xFFFFFFFFFFFFFFF0

    # Call ld_so_start(stack, entry)
    mov rdi, rbp
    sub rsi, 5
    call relibc_ld_so_start

    # Restore original stack, clear registers, and jump to new start function
    mov rsp, rbp
    xor rcx, rcx
    xor rdx, rdx
    xor rdi, rdi
    xor rsi, rsi
    xor r8, r8
    xor r9, r9
    xor r10, r10
    xor r11, r11
    fninit
    jmp rax
"
);

#[cfg(target_arch = "riscv64")]
global_asm!(
    "
.globl _start
_start:
    mv a0, sp
    jal relibc_ld_so_start
    unimp
"
);

#[no_mangle]
pub unsafe extern "C" fn main(_argc: isize, _argv: *const *const i8) -> usize {
    // LD
    0x1D
}

#[linkage = "weak"]
#[no_mangle]
extern "C" fn relibc_panic(_pi: &::core::panic::PanicInfo) -> ! {
    loop {}
}

#[panic_handler]
#[linkage = "weak"]
#[no_mangle]
pub unsafe fn rust_begin_unwind(pi: &::core::panic::PanicInfo) -> ! {
    relibc_panic(pi)
}