user: What is the c source code of the assembly code below:

```asm
<RC4>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x870,%rsp
  mov    %rdi,-0x868(%rbp)
  mov    %rsi,-0x870(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  movl   $0x0,-0x858(%rbp)
  jmp    L23
L83:
  mov    -0x858(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x868(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%edx
  mov    -0x858(%rbp),%eax
  cltq
  mov    %edx,-0x850(%rbp,%rax,4)
  addl   $0x1,-0x858(%rbp)
L23:
  cmpl   $0x2,-0x858(%rbp)
  jle    L83
  movl   $0x0,-0x858(%rbp)
  jmp    L76
L63:
  mov    -0x858(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x870(%rbp),%rax
  add    %rdx,%rax
  mov    -0x858(%rbp),%edx
  lea    0x3(%rdx),%ecx
  mov    (%rax),%edx
  movslq %ecx,%rax
  mov    %edx,-0x850(%rbp,%rax,4)
  addl   $0x1,-0x858(%rbp)
L76:
  cmpl   $0xc,-0x858(%rbp)
  jle    L63
  movl   $0x0,-0x858(%rbp)
  jmp    L8
L39:
  mov    -0x858(%rbp),%eax
  cltq
  mov    -0x858(%rbp),%edx
  mov    %edx,-0x410(%rbp,%rax,4)
  mov    -0x858(%rbp),%eax
  cltd
  shr    $0x1c,%edx
  add    %edx,%eax
  and    $0xf,%eax
  sub    %edx,%eax
  cltq
  mov    -0x850(%rbp,%rax,4),%edx
  mov    -0x858(%rbp),%eax
  cltq
  mov    %edx,-0x810(%rbp,%rax,4)
  addl   $0x1,-0x858(%rbp)
L8:
  cmpl   $0xff,-0x858(%rbp)
  jle    L39
  movl   $0x0,-0x85c(%rbp)
  movl   $0x0,-0x860(%rbp)
  jmp    L19
L37:
  mov    -0x860(%rbp),%eax
  cltq
  mov    -0x410(%rbp,%rax,4),%edx
  mov    -0x85c(%rbp),%eax
  add    %eax,%edx
  mov    -0x860(%rbp),%eax
  cltq
  mov    -0x810(%rbp,%rax,4),%eax
  add    %edx,%eax
  cltd
  shr    $0x18,%edx
  add    %edx,%eax
  movzbl %al,%eax
  sub    %edx,%eax
  mov    %eax,-0x85c(%rbp)
  mov    -0x860(%rbp),%eax
  cltq
  mov    -0x410(%rbp,%rax,4),%eax
  mov    %eax,-0x854(%rbp)
  mov    -0x85c(%rbp),%eax
  cltq
  mov    -0x410(%rbp,%rax,4),%edx
  mov    -0x860(%rbp),%eax
  cltq
  mov    %edx,-0x410(%rbp,%rax,4)
  mov    -0x85c(%rbp),%eax
  cltq
  mov    -0x854(%rbp),%edx
  mov    %edx,-0x410(%rbp,%rax,4)
  addl   $0x1,-0x860(%rbp)
L19:
  cmpl   $0xff,-0x860(%rbp)
  jle    L37
  movl   $0x0,-0x860(%rbp)
  movl   $0x0,-0x85c(%rbp)
  addl   $0x1,-0x860(%rbp)
  mov    -0x860(%rbp),%eax
  cltq
  mov    -0x410(%rbp,%rax,4),%eax
  add    %eax,-0x85c(%rbp)
  mov    -0x860(%rbp),%eax
  cltq
  mov    -0x410(%rbp,%rax,4),%eax
  mov    %eax,-0x854(%rbp)
  mov    -0x85c(%rbp),%eax
  cltq
  mov    -0x410(%rbp,%rax,4),%edx
  mov    -0x860(%rbp),%eax
  cltq
  mov    %edx,-0x410(%rbp,%rax,4)
  mov    -0x85c(%rbp),%eax
  cltq
  mov    -0x854(%rbp),%edx
  mov    %edx,-0x410(%rbp,%rax,4)
  mov    -0x860(%rbp),%eax
  cltq
  mov    -0x410(%rbp,%rax,4),%edx
  mov    -0x85c(%rbp),%eax
  cltq
  mov    -0x410(%rbp,%rax,4),%eax
  add    %edx,%eax
  cltd
  shr    $0x18,%edx
  add    %edx,%eax
  movzbl %al,%eax
  sub    %edx,%eax
  mov    %eax,-0x858(%rbp)
  mov    -0x858(%rbp),%eax
  cltq
  mov    -0x410(%rbp,%rax,4),%eax
  mov    -0x8(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L25
  call   <__stack_chk_fail@plt>
L25:
  leave
  ret
```

assistant: ```c
int RC4(int *IV, int *key) {
  int K[256];
  int S[256];
  int seed[16];
  int i, j, k, t;
  for (k = 0; k < 3; k++)
    seed[k] = IV[k];
  for (k = 0; k < 13; k++)
    seed[k + 3] = key[k];
  for (k = 0; k < 256; k++) {
    S[k] = k;
    K[k] = seed[k % 16];
  }
  j = 0;
  for (i = 0; i < 256; i++) {
    j = (j + S[i] + K[i]) % 256;
    t = S[i];
    S[i] = S[j];
    S[j] = t;
  }
  i = 0;
  j = 0;
  i = i + 1;
  j = j + S[i];
  t = S[i];
  S[i] = S[j];
  S[j] = t;
  k = (S[i] + S[j]) % 256;
  return S[k];
}
```