user: 下面的汇编指令对应的C源代码是什么：

```asm
<encode4b6b>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x40,%rsp
  mov    %rdi,-0x28(%rbp)
  mov    %esi,-0x2c(%rbp)
  mov    %rdx,-0x38(%rbp)
  mov    %rcx,-0x40(%rbp)
  mov    -0x40(%rbp),%rax
  movl   $0x0,(%rax)
  movl   $0x0,-0xc(%rbp)
  movl   $0x0,-0x10(%rbp)
  movl   $0x0,-0x14(%rbp)
  jmp    L0
L15:
  mov    -0x14(%rbp),%eax
  shr    %eax
  mov    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  add    %eax,%eax
  cmp    %eax,-0x14(%rbp)
  jne    L59
  mov    -0x4(%rbp),%edx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  shr    $0x4,%al
  mov    %al,-0x15(%rbp)
  jmp    L1
L59:
  mov    -0x4(%rbp),%edx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  and    $0xf,%eax
  mov    %al,-0x15(%rbp)
L1:
  movsbl -0x15(%rbp),%eax
  mov    %eax,%edi
  call   <get4b6bsymbol@plt>
  mov    %al,-0x15(%rbp)
  mov    -0x10(%rbp),%eax
  shl    $0x6,%eax
  and    $0xffff,%eax
  mov    %eax,-0x10(%rbp)
  movsbl -0x15(%rbp),%eax
  or     %eax,-0x10(%rbp)
  addl   $0x6,-0xc(%rbp)
  cmpl   $0x7,-0xc(%rbp)
  jle    L28
  mov    -0xc(%rbp),%eax
  sub    $0x8,%eax
  mov    -0x10(%rbp),%edx
  mov    %eax,%ecx
  sar    %cl,%edx
  mov    %edx,%eax
  mov    %al,-0x15(%rbp)
  mov    -0x40(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x38(%rbp),%rax
  add    %rax,%rdx
  movzbl -0x15(%rbp),%eax
  mov    %al,(%rdx)
  mov    -0x40(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x40(%rbp),%rax
  mov    %edx,(%rax)
  subl   $0x8,-0xc(%rbp)
  mov    -0xc(%rbp),%eax
  mov    $0x1,%edx
  mov    %eax,%ecx
  shl    %cl,%edx
  mov    %edx,%eax
  sub    $0x1,%eax
  mov    %eax,-0x8(%rbp)
  mov    -0x8(%rbp),%eax
  and    %eax,-0x10(%rbp)
L28:
  addl   $0x1,-0x14(%rbp)
L0:
  mov    -0x2c(%rbp),%eax
  add    %eax,%eax
  cmp    %eax,-0x14(%rbp)
  jb     L15
  cmpl   $0x0,-0xc(%rbp)
  je     L25
  mov    -0xc(%rbp),%eax
  mov    $0x1,%edx
  mov    %eax,%ecx
  shl    %cl,%edx
  mov    %edx,%eax
  sub    $0x1,%eax
  mov    %eax,-0x8(%rbp)
  mov    -0x8(%rbp),%eax
  and    %eax,-0x10(%rbp)
  mov    $0x8,%eax
  sub    -0xc(%rbp),%eax
  mov    %eax,%ecx
  shll   %cl,-0x10(%rbp)
  mov    -0x10(%rbp),%eax
  mov    %al,-0x15(%rbp)
  mov    -0x40(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x38(%rbp),%rax
  add    %rax,%rdx
  movzbl -0x15(%rbp),%eax
  mov    %al,(%rdx)
  mov    -0x40(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x40(%rbp),%rax
  mov    %edx,(%rax)
L25:
  nop
  leave
  ret
```

assistant: ```c
void encode4b6b(char *messageIn, unsigned int bytesIn, char *messageOut, unsigned int *bytesOut) {
  unsigned int i, j;
  int intBuffer;
  int mask;
  int intBitsAvailable;
  char symbol;
  *bytesOut = 0;
  intBitsAvailable = 0;
  intBuffer = 0;
  for (i = 0; i < bytesIn * 2; i++) {
    j = i >> 1;
    if (j * 2 == i) {
      symbol = (messageIn[j] >> 4) & 0x0F;
    } else {
      symbol = messageIn[j] & 0x0F;
    }
    symbol = get4b6bsymbol(symbol);
    intBuffer = (intBuffer << 6) & 0xFFC0;
    intBuffer = intBuffer | symbol;
    intBitsAvailable += 6;
    if (intBitsAvailable >= 8) {
      symbol = intBuffer >> (intBitsAvailable - 8);
      messageOut[*bytesOut] = symbol;
      (*bytesOut)++;
      intBitsAvailable -= 8;
      mask = (1 << intBitsAvailable) - 1;
      intBuffer = intBuffer & mask;
    }
  }
  if (intBitsAvailable != 0) {
    mask = (1 << intBitsAvailable) - 1;
    intBuffer = intBuffer & mask;
    intBuffer = intBuffer << (8 - intBitsAvailable);
    symbol = intBuffer & 0x00FF;
    messageOut[*bytesOut] = symbol;
    (*bytesOut)++;
  }
}
```