user: 下面的汇编指令对应的C源代码是什么：

```asm
<filtblocktag>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x138,%rsp
  mov    %rdi,0x8(%rsp)
  mov    %rsi,%r12
  mov    %fs:0x28,%rax
  mov    %rax,0x128(%rsp)
  xor    %eax,%eax
  lea    0x1e(%rsp),%rdi
  mov    $0x2,%edx
  mov    $0x0,%esi
  call   <memset@plt>
  lea    0x20(%rsp),%rdi
  mov    $0x100,%edx
  mov    $0x0,%esi
  call   <memset@plt>
  mov    %r12,%rdi
  call   <fgetc@plt>
  mov    D18(%rip),%rdx
  cmp    (%rdx),%al
  je     L98
  mov    $0x0,%r15d
  mov    $0x1,%r14d
  mov    $0x0,%ebx
  mov    $0x0,%ebp
  lea    0x1e(%rsp),%r13
  jmp    L122
L116:
  cmp    $0x62,%al
  jne    L7
  cmp    $0x1,%r15d
  mov    $0x0,%eax
  cmove  %eax,%r14d
  lea    0x20(%rsp),%rdi
  mov    %r13,%rsi
  call   <strcat@plt>
  add    $0x1,%ebp
  jmp    L91
L45:
  lea    0x20(%rsp),%rdi
  mov    %r13,%rsi
  call   <strcat@plt>
  mov    $0x1,%r15d
  mov    $0x1,%ebp
L91:
  mov    %r12,%rdi
  call   <fgetc@plt>
  add    $0x1,%ebx
  mov    D18(%rip),%rdx
  cmp    %al,(%rdx)
  je     L22
L122:
  mov    %al,0x1e(%rsp)
  cmp    $0x3e,%al
  je     L30
  jg     L116
  cmp    $0x2f,%al
  je     L121
  cmp    $0x3c,%al
  jne    L7
  test   %ebp,%ebp
  je     L45
  lea    0x20(%rsp),%rbp
  mov    0x8(%rsp),%rsi
  mov    %rbp,%rdi
  call   <fputs@plt>
  mov    $0x100,%edx
  mov    $0x0,%esi
  mov    %rbp,%rdi
  call   <memset@plt>
  jmp    L45
L30:
  lea    0x20(%rsp),%rdi
  mov    %r13,%rsi
  call   <strcat@plt>
  cmp    $0x1,%r14d
  je     L149
L90:
  lea    0x20(%rsp),%rdi
  mov    $0x100,%edx
  mov    $0x0,%esi
  call   <memset@plt>
  mov    $0x0,%r15d
  mov    $0x1,%r14d
  mov    $0x0,%ebp
  jmp    L91
L149:
  lea    0x20(%rsp),%rdi
  mov    0x8(%rsp),%rsi
  call   <fputs@plt>
  jmp    L90
L121:
  lea    0x20(%rsp),%rdi
  mov    %r13,%rsi
  call   <strcat@plt>
  add    $0x1,%ebp
  jmp    L91
L7:
  lea    0x20(%rsp),%rdi
  mov    %r13,%rsi
  call   <strcat@plt>
  add    $0x1,%ebp
  mov    $0x0,%r15d
  jmp    L91
L98:
  mov    $0x0,%ebx
L22:
  mov    0x128(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L18
  mov    %ebx,%eax
  add    $0x138,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L18:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int filtblocktag(FILE *destination, FILE *source) {
  char curchar;
  char inputbuf[2];
  char outputbuf[256];
  int buflocation = 0;
  int charcount = 0;
  int intag = 0;
  int endtag = 0;
  int copytag = 1;
  int prevtag = 0;
  memset(inputbuf, 0, 2);
  memset(outputbuf, 0, 256);
  curchar = fgetc(source);
  while (curchar != EOF) {
    inputbuf[0] = curchar;
    switch (inputbuf[0]) {
    case '<':
      intag = 1;
      prevtag = 1;
      if (buflocation != 0) {
        fputs(outputbuf, destination);
        buflocation = 0;
        memset(outputbuf, 0, 256);
      }
      strcat(outputbuf, inputbuf);
      buflocation++;
      break;
    case '>':
      strcat(outputbuf, inputbuf);
      if (copytag == 1)
        fputs(outputbuf, destination);
      memset(outputbuf, 0, 256);
      buflocation = 0;
      intag = 0;
      copytag = 1;
      endtag = 0;
      prevtag = 0;
      break;
    case '/':
      if (intag == 1 && prevtag == 1) {
        endtag = 1;
      }
      strcat(outputbuf, inputbuf);
      buflocation++;
      break;
    case 'b':
      if (prevtag == 1)
        copytag = 0;
      strcat(outputbuf, inputbuf);
      buflocation++;
      break;
    default:
      strcat(outputbuf, inputbuf);
      prevtag = 0;
      buflocation++;
      break;
    }
    curchar = fgetc(source);
    charcount++;
  }
  return charcount;
}
```