user: 请将这段汇编代码片段转换成等效的C代码：

```asm
<http_base64decode>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x140,%rsp
  mov    %rdi,-0x128(%rbp)
  mov    %esi,-0x12c(%rbp)
  mov    %rdx,-0x138(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  movl   $0x0,-0x118(%rbp)
  movl   $0x0,-0x114(%rbp)
  movq   $0xffffffffffffffff,-0x110(%rbp)
  movq   $0xffffffffffffffff,-0x108(%rbp)
  movq   $0xffffffffffffffff,-0x100(%rbp)
  movq   $0xffffffffffffffff,-0xf8(%rbp)
  mov    $0xffffffffffffffff,%rax
  movabs $0x3fffffff3effffff,%rdx
  mov    %rax,-0xf0(%rbp)
  mov    %rdx,-0xe8(%rbp)
  movabs $0x3b3a393837363534,%rax
  movabs $0xffff00ffffff3d3c,%rdx
  mov    %rax,-0xe0(%rbp)
  mov    %rdx,-0xd8(%rbp)
  movabs $0x6050403020100ff,%rax
  movabs $0xe0d0c0b0a090807,%rdx
  mov    %rax,-0xd0(%rbp)
  mov    %rdx,-0xc8(%rbp)
  movabs $0x161514131211100f,%rax
  mov    $0xffffffffff191817,%rdx
  mov    %rax,-0xc0(%rbp)
  mov    %rdx,-0xb8(%rbp)
  movabs $0x201f1e1d1c1b1aff,%rax
  movabs $0x2827262524232221,%rdx
  mov    %rax,-0xb0(%rbp)
  mov    %rdx,-0xa8(%rbp)
  movabs $0x302f2e2d2c2b2a29,%rax
  mov    $0xffffffffff333231,%rdx
  mov    %rax,-0xa0(%rbp)
  mov    %rdx,-0x98(%rbp)
  movq   $0xffffffffffffffff,-0x90(%rbp)
  movq   $0xffffffffffffffff,-0x88(%rbp)
  movq   $0xffffffffffffffff,-0x80(%rbp)
  movq   $0xffffffffffffffff,-0x78(%rbp)
  movq   $0xffffffffffffffff,-0x70(%rbp)
  movq   $0xffffffffffffffff,-0x68(%rbp)
  movq   $0xffffffffffffffff,-0x60(%rbp)
  movq   $0xffffffffffffffff,-0x58(%rbp)
  movq   $0xffffffffffffffff,-0x50(%rbp)
  movq   $0xffffffffffffffff,-0x48(%rbp)
  movq   $0xffffffffffffffff,-0x40(%rbp)
  movq   $0xffffffffffffffff,-0x38(%rbp)
  movq   $0xffffffffffffffff,-0x30(%rbp)
  movq   $0xffffffffffffffff,-0x28(%rbp)
  movq   $0xffffffffffffffff,-0x20(%rbp)
  movq   $0xffffffffffffffff,-0x18(%rbp)
  jmp    L5
L21:
  mov    -0x118(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x128(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  cltq
  movzbl -0x110(%rbp,%rax,1),%eax
  movsbl %al,%eax
  shl    $0x2,%eax
  mov    %eax,%ecx
  mov    -0x118(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x128(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  cltq
  movzbl -0x110(%rbp,%rax,1),%eax
  sar    $0x4,%al
  or     %eax,%ecx
  mov    -0x114(%rbp),%eax
  lea    0x1(%rax),%edx
  mov    %edx,-0x114(%rbp)
  movslq %eax,%rdx
  mov    -0x138(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  mov    -0x118(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x128(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  cltq
  movzbl -0x110(%rbp,%rax,1),%eax
  movsbl %al,%eax
  shl    $0x4,%eax
  mov    %eax,%ecx
  mov    -0x118(%rbp),%eax
  cltq
  lea    0x2(%rax),%rdx
  mov    -0x128(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  cltq
  movzbl -0x110(%rbp,%rax,1),%eax
  sar    $0x2,%al
  or     %eax,%ecx
  mov    -0x114(%rbp),%eax
  lea    0x1(%rax),%edx
  mov    %edx,-0x114(%rbp)
  movslq %eax,%rdx
  mov    -0x138(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  mov    -0x118(%rbp),%eax
  cltq
  lea    0x2(%rax),%rdx
  mov    -0x128(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  cltq
  movzbl -0x110(%rbp,%rax,1),%eax
  movsbl %al,%eax
  shl    $0x6,%eax
  mov    %eax,%ecx
  mov    -0x118(%rbp),%eax
  cltq
  lea    0x3(%rax),%rdx
  mov    -0x128(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  cltq
  movzbl -0x110(%rbp,%rax,1),%eax
  or     %eax,%ecx
  mov    -0x114(%rbp),%eax
  lea    0x1(%rax),%edx
  mov    %edx,-0x114(%rbp)
  movslq %eax,%rdx
  mov    -0x138(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  addl   $0x4,-0x118(%rbp)
L5:
  mov    -0x118(%rbp),%eax
  cmp    -0x12c(%rbp),%eax
  jl     L21
  mov    -0x114(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x138(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  mov    -0x114(%rbp),%eax
  mov    -0x8(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L11
  call   <__stack_chk_fail@plt>
L11:
  leave
  ret
```

assistant: ```c
int http_base64decode(unsigned char *src, int src_len, unsigned char *dst) {
  int i = 0, j = 0;
  char base64_decode_map[256] = {255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 255, 0, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255, 255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255};
  for (; i < src_len; i += 4) {
    dst[j++] = (base64_decode_map[src[i]] << 2) | (base64_decode_map[src[i + 1]] >> 4);
    dst[j++] = (base64_decode_map[src[i + 1]] << 4) | (base64_decode_map[src[i + 2]] >> 2);
    dst[j++] = (base64_decode_map[src[i + 2]] << 6) | (base64_decode_map[src[i + 3]]);
  }
  dst[j] = '\0';
  return j;
}
```