user: 请将这段汇编代码片段转换成等效的C代码:

```asm
<getvalue>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x2c8,%rsp
  mov    %rdi,%r13
  mov    %rsi,0x8(%rsp)
  mov    %rdx,%r15
  mov    %fs:0x28,%rax
  mov    %rax,0x2b8(%rsp)
  xor    %eax,%eax
  mov    D1(%rip),%rax
  mov    (%rax),%edx
  mov    $0x0,%esi
  call   <fseek@plt>
  lea    0xf0(%rsp),%r14
  lea    0xe8(%rsp),%r12
  jmp    L209
L192:
  add    $0x1,%rbx
L68:
  movsbl (%rbx),%edi
  call   <isspace@plt>
  test   %rax,%rax
  jne    L192
  movzbl (%rbx),%edi
  cmp    $0x23,%dil
  je     L209
  lea    0x10(%rsp),%rbp
  test   %dil,%dil
  jne    L273
L209:
  mov    %r13,%rdx
  mov    $0x1c4,%esi
  mov    %r14,%rdi
  call   <fgets@plt>
  test   %rax,%rax
  je     L198
  lea    0xf0(%rsp),%rbx
  jmp    L68
L213:
  cmp    %r12,%rbp
  je     L53
  add    $0x1,%rbx
  add    $0x1,%rbp
  movzbl -0x1(%rbx),%eax
  mov    %al,-0x1(%rbp)
  movzbl (%rbx),%edi
  test   %dil,%dil
  je     L45
L273:
  cmp    $0x5f,%dil
  je     L213
  movsbl %dil,%edi
  call   <isalnum@plt>
  test   %rax,%rax
  jne    L213
L45:
  movb   $0x0,0x0(%rbp)
  movzbl (%rbx),%eax
  cmp    $0x3d,%al
  je     L83
  test   %al,%al
  je     L83
L16:
  add    $0x1,%rbx
  movzbl (%rbx),%eax
  cmp    $0x3d,%al
  je     L83
  test   %al,%al
  jne    L16
L83:
  test   %al,%al
  je     L209
L204:
  mov    %rbx,%rbp
  add    $0x1,%rbx
  movsbl (%rbx),%edi
  call   <isspace@plt>
  test   %rax,%rax
  jne    L204
  movzbl (%rbx),%eax
  test   %al,%al
  je     L209
  cmp    $0x22,%al
  je     L152
L5:
  lea    0xd8(%rbx),%rcx
  mov    %r15,%rdx
L43:
  add    $0x1,%rbx
  add    $0x1,%rdx
  mov    %al,-0x1(%rdx)
  movzbl (%rbx),%eax
  test   %al,%al
  je     L88
  cmp    $0x22,%al
  je     L88
  cmp    %rcx,%rbx
  jne    L43
  mov    $0xfffffffd,%eax
  jmp    L57
L152:
  lea    0x2(%rbp),%rbx
  movzbl 0x2(%rbp),%eax
  test   %al,%al
  je     L44
  cmp    $0x22,%al
  jne    L5
L44:
  mov    %r15,%rdx
L88:
  movb   $0x0,(%rdx)
  lea    0x10(%rsp),%rsi
  mov    0x8(%rsp),%rdi
  call   <strcmp@plt>
  test   %eax,%eax
  jne    L209
  jmp    L57
L198:
  mov    $0xfffffffe,%eax
  jmp    L57
L53:
  mov    $0xfffffffd,%eax
L57:
  mov    0x2b8(%rsp),%rdx
  sub    %fs:0x28,%rdx
  jne    L171
  add    $0x2c8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L171:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int getvalue(FILE *conf, char const *key, char *value) {
  char readbuff[(2 * 216 + 20)];
  char keybuff[216];
  char *pb, *pkey, *pval;
  fseek(conf, 0L, SEEK_SET);
  while (NULL != fgets(readbuff, (2 * 216 + 20), conf)) {
    pb = readbuff;
    pkey = keybuff;
    pval = value;
    while (isspace(*pb))
      ++pb;
    if ('#' == *pb || '\0' == *pb)
      continue;
    while ('\0' != *pb && ('_' == *pb || isalnum(*pb))) {
      if (pkey >= keybuff + 216)
        return -3;
      *pkey++ = *pb++;
    }
    *pkey = '\0';
    while ('=' != *pb && '\0' != *pb)
      ++pb;
    if ('\0' == *pb)
      continue;
    while (isspace(*++pb))
      ;
    if ('\0' == *pb)
      continue;
    if ('"' == *pb)
      ++pb;
    while ('\0' != *pb && '"' != *pb) {
      if (pval >= value + 216)
        return -3;
      *pval++ = *pb++;
    }
    *pval = '\0';
    if (!strcmp(key, keybuff)) {
      return 0;
    }
  }
  return -2;
}
```