user: 下面的汇编指令对应的C源代码是什么:

```asm
<base64_encode>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x18(%rbp)
  mov    %rsi,-0x20(%rbp)
  mov    %edx,-0x24(%rbp)
  mov    -0x18(%rbp),%rax
  mov    %rax,-0x8(%rbp)
  movl   $0x13,-0x10(%rbp)
  jmp    L80
L33:
  mov    -0x20(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x20(%rbp)
  movzbl (%rax),%eax
  movsbl %al,%eax
  shl    $0x10,%eax
  mov    %eax,-0xc(%rbp)
  cmpl   $0x1,-0x24(%rbp)
  jbe    L93
  mov    -0x20(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x20(%rbp)
  movzbl (%rax),%eax
  movsbl %al,%eax
  shl    $0x8,%eax
  or     %eax,-0xc(%rbp)
L93:
  cmpl   $0x2,-0x24(%rbp)
  jbe    L89
  mov    -0x20(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x20(%rbp)
  movzbl (%rax),%eax
  movsbl %al,%eax
  or     %eax,-0xc(%rbp)
L89:
  mov    -0xc(%rbp),%eax
  shr    $0x12,%eax
  and    $0x3f,%eax
  mov    %eax,%ecx
  mov    -0x18(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x18(%rbp)
  mov    %ecx,%ecx
  lea    D20(%rip),%rdx
  movzbl (%rcx,%rdx,1),%edx
  mov    %dl,(%rax)
  mov    -0xc(%rbp),%eax
  shr    $0xc,%eax
  and    $0x3f,%eax
  mov    %eax,%ecx
  mov    -0x18(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x18(%rbp)
  mov    %ecx,%ecx
  lea    D20(%rip),%rdx
  movzbl (%rcx,%rdx,1),%edx
  mov    %dl,(%rax)
  cmpl   $0x1,-0x24(%rbp)
  jbe    L32
  mov    -0xc(%rbp),%eax
  shr    $0x6,%eax
  and    $0x3f,%eax
  mov    %eax,%edx
  lea    D20(%rip),%rax
  movzbl (%rdx,%rax,1),%edx
  jmp    L56
L32:
  mov    $0x3d,%edx
L56:
  mov    -0x18(%rbp),%rax
  lea    0x1(%rax),%rcx
  mov    %rcx,-0x18(%rbp)
  mov    %dl,(%rax)
  cmpl   $0x2,-0x24(%rbp)
  jbe    L75
  mov    -0xc(%rbp),%eax
  and    $0x3f,%eax
  mov    %eax,%edx
  lea    D20(%rip),%rax
  movzbl (%rdx,%rax,1),%edx
  jmp    L23
L75:
  mov    $0x3d,%edx
L23:
  mov    -0x18(%rbp),%rax
  lea    0x1(%rax),%rcx
  mov    %rcx,-0x18(%rbp)
  mov    %dl,(%rax)
  cmpl   $0x2,-0x24(%rbp)
  jbe    L59
  subl   $0x1,-0x10(%rbp)
  cmpl   $0x0,-0x10(%rbp)
  jne    L103
  mov    -0x18(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x18(%rbp)
  movb   $0xa,(%rax)
  movl   $0x13,-0x10(%rbp)
L103:
  subl   $0x3,-0x24(%rbp)
L80:
  cmpl   $0x0,-0x24(%rbp)
  jne    L33
  jmp    L55
L59:
  nop
L55:
  mov    -0x18(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x18(%rbp)
  movb   $0xa,(%rax)
  mov    -0x18(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x18(%rbp)
  movb   $0x0,(%rax)
  mov    -0x18(%rbp),%rax
  sub    -0x8(%rbp),%rax
  sub    $0x1,%eax
  pop    %rbp
  ret
```

tool_calls: name: read_data
arguments: data_label: D20
type: string

tool: D20: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/

assistant: ```c
unsigned base64_encode(char *dst, const char *src, unsigned srclen) {
  static const char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  char *start = dst;
  int nline = 19;
  for (; srclen; srclen -= 3) {
    unsigned int buf = *(src++) << 16;
    if (srclen > 1)
      buf |= *(src++) << 8;
    if (srclen > 2)
      buf |= *(src++);
    *(dst++) = alphabet[(buf >> 18) & 0x3f];
    *(dst++) = alphabet[(buf >> 12) & 0x3f];
    *(dst++) = (srclen > 1) ? alphabet[(buf >> 6) & 0x3f] : '=';
    *(dst++) = (srclen > 2) ? alphabet[buf & 0x3f] : '=';
    if (srclen < 3)
      break;
    if (!--nline) {
      *(dst++) = '\n';
      nline = 19;
    }
  }
  *(dst++) = '\n';
  *(dst++) = '\0';
  return (dst - start - 1);
}
```