user: Translate the below assembly code into C programming language:

```asm
<filtblocktag>:
  endbr64
  push   %r15
  mov    $0x2,%edx
  push   %r14
  push   %r13
  mov    %rsi,%r13
  xor    %esi,%esi
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x138,%rsp
  mov    %rdi,0x8(%rsp)
  lea    0x1e(%rsp),%r14
  lea    0x20(%rsp),%rbp
  mov    %r14,%rdi
  mov    %fs:0x28,%rax
  mov    %rax,0x128(%rsp)
  xor    %eax,%eax
  call   <memset@plt>
  mov    $0x100,%edx
  xor    %esi,%esi
  mov    %rbp,%rdi
  call   <memset@plt>
  mov    %r13,%rdi
  call   <fgetc@plt>
  mov    D8(%rip),%r15
  cmp    (%r15),%al
  je     L67
  movl   $0x0,0x4(%rsp)
  xor    %r12d,%r12d
  xor    %ebx,%ebx
  movl   $0x1,(%rsp)
  jmp    L31
  cs nopw 0x0(%rax,%rax,1)
L124:
  cmp    $0x3c,%al
  jne    L40
  test   %ebx,%ebx
  jne    L78
L167:
  mov    %r14,%rsi
  mov    %rbp,%rdi
  mov    $0x1,%ebx
  call   <strcat@plt>
  movl   $0x1,0x4(%rsp)
L81:
  mov    %r13,%rdi
  add    $0x1,%r12d
  call   <fgetc@plt>
  cmp    %al,(%r15)
  je     L146
L31:
  mov    %al,0x1e(%rsp)
  cmp    $0x3e,%al
  je     L65
  jg     L160
  cmp    $0x2f,%al
  jne    L124
  mov    %r14,%rsi
  mov    %rbp,%rdi
  add    $0x1,%ebx
  call   <strcat@plt>
  jmp    L81
  nopl   0x0(%rax,%rax,1)
L160:
  cmp    $0x62,%al
  jne    L40
  xor    %eax,%eax
  cmpl   $0x1,0x4(%rsp)
  cmovne (%rsp),%eax
  mov    %r14,%rsi
  mov    %rbp,%rdi
  add    $0x1,%ebx
  mov    %eax,(%rsp)
  call   <strcat@plt>
  jmp    L81
  nopw   0x0(%rax,%rax,1)
L65:
  mov    %r14,%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  cmpl   $0x1,(%rsp)
  je     L57
L101:
  mov    $0x100,%edx
  xor    %esi,%esi
  mov    %rbp,%rdi
  xor    %ebx,%ebx
  call   <memset@plt>
  movl   $0x0,0x4(%rsp)
  movl   $0x1,(%rsp)
  jmp    L81
  nopw   0x0(%rax,%rax,1)
L40:
  mov    %r14,%rsi
  mov    %rbp,%rdi
  add    $0x1,%ebx
  call   <strcat@plt>
  movl   $0x0,0x4(%rsp)
  jmp    L81
  nopl   0x0(%rax,%rax,1)
L67:
  xor    %r12d,%r12d
  nopl   0x0(%rax,%rax,1)
L146:
  mov    0x128(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L136
  add    $0x138,%rsp
  mov    %r12d,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax,%rax,1)
L78:
  mov    0x8(%rsp),%rsi
  mov    %rbp,%rdi
  call   <fputs@plt>
  mov    $0x100,%edx
  xor    %esi,%esi
  mov    %rbp,%rdi
  call   <memset@plt>
  jmp    L167
  nopl   0x0(%rax)
L57:
  mov    0x8(%rsp),%rsi
  mov    %rbp,%rdi
  call   <fputs@plt>
  jmp    L101
L136:
  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;
}
```