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/*
    A toy implementation of the kill command with a few simplifications
        - Passing PID in argv[1]
        - Hard code the signal number to 9 (for SIGKILL)
        - Exit the program with the return value of the kill system call
    Solving https://blog.codingconfessions.com/p/x86-assembly-exercise-1 , but in ARM64 assembly
    Compiles to a 211 byte binary!
    `as -o kill.o kill.S && ld -s -o kk kill.o` to compile. Run strip / sstrip to remove the section headers
 */
.equ SYS_KILL, 129

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// Adapted from http://wiki.osdev.org/QEMU_AArch64_Virt_Bare_Bones and https://krinkinmu.github.io/2020/11/29/PL011.html
// Uses UEFI shell to load the kernel
// Run on qemu using: `qemu-system-aarch64 -machine virt -cpu max -drive if=pflash,format=raw,file=./OVMF.fd -drive format=raw,file=fat:rw:./root -net none -serial telnet:localhost:1234,server -monitor telnet:localhost:1235,server,nowait -serial mon:stdio  -nographic`
.equ UART_ADDR, 0x9000000
  .data
  msg:
  .ascii        "Hello World!\n";
  len = . - msg
  .text
.global _start

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// as -o /tmp/calc.o calc.S && ld -s -o /tmp/calc /tmp/calc.o && strip --strip-section-headers /tmp/calc

.equ SYS_MEMFD_CREATE, 279
.equ SYS_FTRUNCATE, 46
.equ SYS_MMAP, 222
.equ SYS_READ, 63
.equ SYS_WRITE, 64
.equ SYS_EXIT, 93
.equ BUF_SIZE, 64
.equ PAGE_SIZE, 4096

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/*
  Teensy Elf using GNU as and objcopy
  as -o teensy.o teensy.S && objcopy -O binary teensy.o teensy.bin && chmod +x teensy.bin

  References:
  Elf Format details: https://gist.github.com/x0nu11byt3/bcb35c3de461e5fb66173071a2379779
  Build a Teensy Elf (x86) file: https://www.muppetlabs.com/~breadbox/software/tiny/teensy.html
  Adding Elf headers using GNU as: https://stackoverflow.com/q/77244360
  
*/

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.equ BUF_SIZE, 0x1000
    .section .text
    .global _start
_start:
    sub sp, sp, #BUF_SIZE         // Reserve 4096 bytes on the stack
    mov x1, sp                    // x1 -> buffer, also passed to write
    mov x2, #BUF_SIZE             // x2 = total size, also to be passed to write syscall
    movz w3, #0x0A79          // lower 16 bits
    mov x4, #0                // x4 = counter
fill_loop:

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.equ SYS_clone3, 435
.equ SYS_write, 64
.equ SYS_exit, 93
.equ CHILD_STACK_SIZE, 0x4000           // 16 KB per child
.equ CLONE_VM, 0x00000100
.equ CLONE_FS, 0x00000200
.equ CLONE_FILES, 0x00000400
.equ CLONE_SIGHAND, 0x00000800
.equ CLONE_PARENT, 0x00008000
.equ CLONE_THREAD, 0x00010000

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.equ SYS_READ, 63
.equ SYS_WRITE, 64
.equ SYS_EXIT, 93
.equ SYS_SOCKET, 198
.equ SYS_BIND, 200
.equ SYS_LISTEN, 201
.equ SYS_ACCEPT, 202
.equ SYS_CLOSE, 57
.equ SYS_OPENAT, 56
.equ SYS_SENDFILE, 71

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// Snake for Linux terminal
// Fits in a QR code!
// Compile with:
// zig build-exe snek.zig -O ReleaseSmall -target x86_64-linux -fstrip -flto -fsingle-threaded -femit-bin=snek_x64
// zig build-exe snek.zig -O ReleaseSmall -target aarch64-linux -fstrip -flto -fsingle-threaded -femit-bin=snek_aarch64
// Run `sstrip -z` from https://www.muppetlabs.com/~breadbox/software/elfkickers.html to reduce binary size even further
// Currently, snek_x64 is 2616 bytes and snek_aarch64 is 2941 bytes
// Threshold for a binary QR code is 2953 bytes
// Encode using:
// qrencode -8 -r snek_aarch64 -o qr_aarch64.png

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/*
  Compile with one of the following: 
    zig cc -v -s -Os -target aarch64-linux-musl -nostdlib -flto -static shell.c  -o csh
    zig cc -v -s -Os -target aarch64-linux-gnu  -nostdlib -flto -static shell.c  -o csh

	CLANG:
		clang -v -s -Oz -ffreestanding -nostdlib -fno-stack-protector -Wl,--entry=_start -Wl,--gc-sections -Wl,-z,now -flto -static -o csh  shell.c
		musl-clang -v -s -Os -nostdlib -nostartfiles -fno-stack-protector -Wl,--entry=_start -Wl,--gc-sections -Wl,-z,now -flto -nostdinc -static -o csh  shell.c

  GCC (some things DO NOT WORK like `pwd`):

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# %%
import os
os.environ["KMP_DUPLICATE_LIB_OK"] ="TRUE"
import sys
import re
import time
import torch as t
import numpy as np
from pathlib import Path