user: 请将这段汇编代码片段转换成等效的C代码:

```asm
<com_urlDecode>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %rbx
  sub    $0x48,%rsp
  mov    %rdi,-0x48(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x18(%rbp)
  xor    %eax,%eax
  mov    %rsp,%rax
  mov    %rax,%rbx
  mov    D2(%rip),%rax
  mov    (%rax),%eax
  movslq %eax,%rdx
  sub    $0x1,%rdx
  mov    %rdx,-0x30(%rbp)
  movslq %eax,%rdx
  mov    %rdx,%r10
  mov    $0x0,%r11d
  movslq %eax,%rdx
  mov    %rdx,%r8
  mov    $0x0,%r9d
  cltq
  mov    $0x10,%edx
  sub    $0x1,%rdx
  add    %rdx,%rax
  mov    $0x10,%esi
  mov    $0x0,%edx
  div    %rsi
  imul   $0x10,%rax,%rax
  mov    %rax,%rcx
  and    $0xfffffffffffff000,%rcx
  mov    %rsp,%rdx
  sub    %rcx,%rdx
L115:
  cmp    %rdx,%rsp
  je     L127
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  jmp    L115
L127:
  mov    %rax,%rdx
  and    $0xfff,%edx
  sub    %rdx,%rsp
  mov    %rax,%rdx
  and    $0xfff,%edx
  test   %rdx,%rdx
  je     L5
  and    $0xfff,%eax
  sub    $0x8,%rax
  add    %rsp,%rax
  orq    $0x0,(%rax)
L5:
  mov    %rsp,%rax
  add    $0x0,%rax
  mov    %rax,-0x28(%rbp)
  mov    -0x48(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %rax,-0x20(%rbp)
  movl   $0x0,-0x38(%rbp)
  movl   $0x0,-0x34(%rbp)
  jmp    L42
L77:
  mov    -0x38(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  cmp    $0x2b,%al
  jne    L104
  mov    -0x28(%rbp),%rdx
  mov    -0x34(%rbp),%eax
  cltq
  movb   $0x20,(%rdx,%rax,1)
  jmp    L35
L104:
  mov    -0x38(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  cmp    $0x25,%al
  jne    L135
  addl   $0x1,-0x38(%rbp)
  mov    -0x38(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  cmp    $0x40,%al
  jbe    L108
  mov    -0x38(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  sub    $0x37,%eax
  mov    %al,-0x39(%rbp)
  jmp    L80
L108:
  mov    -0x38(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  sub    $0x30,%eax
  mov    %al,-0x39(%rbp)
L80:
  shlb   $0x4,-0x39(%rbp)
  addl   $0x1,-0x38(%rbp)
  mov    -0x38(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  cmp    $0x40,%al
  jbe    L128
  mov    -0x38(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%edx
  movzbl -0x39(%rbp),%eax
  add    %edx,%eax
  sub    $0x37,%eax
  mov    %al,-0x39(%rbp)
  jmp    L92
L128:
  mov    -0x38(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%edx
  movzbl -0x39(%rbp),%eax
  add    %edx,%eax
  sub    $0x30,%eax
  mov    %al,-0x39(%rbp)
L92:
  mov    -0x28(%rbp),%rdx
  mov    -0x34(%rbp),%eax
  cltq
  movzbl -0x39(%rbp),%ecx
  mov    %cl,(%rdx,%rax,1)
  jmp    L35
L135:
  mov    -0x38(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%ecx
  mov    -0x28(%rbp),%rdx
  mov    -0x34(%rbp),%eax
  cltq
  mov    %cl,(%rdx,%rax,1)
L35:
  addl   $0x1,-0x38(%rbp)
  addl   $0x1,-0x34(%rbp)
L42:
  mov    -0x38(%rbp),%eax
  cltq
  cmp    %rax,-0x20(%rbp)
  ja     L77
  mov    -0x28(%rbp),%rdx
  mov    -0x34(%rbp),%eax
  cltq
  movb   $0x0,(%rdx,%rax,1)
  mov    -0x28(%rbp),%rdx
  mov    -0x48(%rbp),%rax
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcpy@plt>
  mov    %rbx,%rsp
  nop
  mov    -0x18(%rbp),%rax
  sub    %fs:0x28,%rax
  je     L62
  call   <__stack_chk_fail@plt>
L62:
  mov    -0x8(%rbp),%rbx
  leave
  ret
```

assistant: ```c
void com_urlDecode(unsigned char *src) {
  int i, j;
  size_t length;
  unsigned char dst[BUFSIZ];
  unsigned char calc;
  length = strlen(src);
  for (i = 0, j = 0; i < length; i++, j++) {
    if (src[i] == '+')
      dst[j] = ' ';
    else if (src[i] == '%') {
      i++;
      if (src[i] >= 'A')
        calc = src[i] - 'A' + 10;
      else
        calc = src[i] - '0';
      calc = calc << 4;
      i++;
      if (src[i] >= 'A')
        calc += src[i] - 'A' + 10;
      else
        calc += src[i] - '0';
      dst[j] = calc;
    } else {
      dst[j] = src[i];
    }
  }
  dst[j] = '\0';
  strcpy(src, dst);
}
```