user: Demonstrate the C code that generates the assembly output below:

```asm
<qword_get>:
  endbr64
  push   %r15
  push   %r14
  mov    %edx,%r14d
  push   %r13
  push   %r12
  mov    %rdi,%r12
  push   %rbp
  mov    %rsi,%rbp
  push   %rbx
  sub    $0x8,%rsp
  mov    (%rdi),%rbx
  movzbl (%rbx),%eax
  cmp    $0x20,%al
  jne    L22
  nopl   (%rax)
L109:
  movzbl 0x1(%rbx),%eax
  add    $0x1,%rbx
  cmp    $0x20,%al
  je     L109
L22:
  cmp    $0x5c,%al
  je     L76
  test   $0xdf,%al
  je     L133
  cmp    $0xa,%al
  je     L133
L27:
  sub    $0x1,%r14d
  xor    %r13d,%r13d
  test   %r14d,%r14d
  jg     L213
  jmp    L201
  nopl   (%rax)
L85:
  add    $0x1,%rbx
L167:
  mov    %al,-0x1(%rbp)
  movzbl (%rbx),%eax
  test   $0xdf,%al
  je     L293
  cmp    $0xa,%al
  je     L293
  cmp    %r13d,%r14d
  je     L201
L213:
  add    $0x1,%rbp
  add    $0x1,%r13d
  cmp    $0x5c,%al
  jne    L85
  movsbl 0x1(%rbx),%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L138
  cmpb   $0x33,0x1(%rbx)
  jle    L154
L138:
  movzbl (%rbx),%eax
  jmp    L85
  nopl   0x0(%rax)
L328:
  movzbl (%rbx),%eax
  test   $0xdf,%al
  je     L293
  cmp    $0xa,%al
  jne    L201
L293:
  cmp    $0x20,%al
  jne    L39
  nopl   0x0(%rax,%rax,1)
L232:
  add    $0x1,%rbx
  cmpb   $0x20,(%rbx)
  je     L232
L39:
  mov    %rbx,(%r12)
  movb   $0x0,0x0(%rbp)
L116:
  add    $0x8,%rsp
  mov    %r13d,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax,%rax,1)
L76:
  cmpb   $0x78,0x1(%rbx)
  jne    L27
  add    $0x2,%rbx
  xor    %r13d,%r13d
  jmp    L244
  nopl   0x0(%rax,%rax,1)
L178:
  movsbl (%rbx),%r15d
  sub    $0x30,%r15d
L266:
  movsbl 0x1(%rbx),%edi
  shl    $0x4,%r15d
  call   <isdigit@plt>
  test   %rax,%rax
  je     L71
  movsbl 0x1(%rbx),%eax
  sub    $0x30,%eax
L239:
  add    $0x1,%rbp
  or     %r15d,%eax
  add    $0x2,%rbx
  add    $0x1,%r13d
  mov    %al,-0x1(%rbp)
L244:
  movsbl (%rbx),%edi
  call   <isxdigit@plt>
  test   %rax,%rax
  je     L328
  movsbl 0x1(%rbx),%edi
  call   <isxdigit@plt>
  cmp    %r14d,%r13d
  jge    L328
  test   %rax,%rax
  je     L328
  movsbl (%rbx),%edi
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L178
  movsbl (%rbx),%edi
  call   <toupper@plt>
  movsbl %al,%r15d
  sub    $0x37,%r15d
  jmp    L266
  xchg   %ax,%ax
L71:
  movsbl 0x1(%rbx),%edi
  call   <toupper@plt>
  movsbl %al,%eax
  sub    $0x37,%eax
  jmp    L239
  nopl   0x0(%rax)
L154:
  movsbl 0x2(%rbx),%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L138
  cmpb   $0x37,0x2(%rbx)
  jg     L138
  movsbl 0x3(%rbx),%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L138
  movzbl 0x3(%rbx),%eax
  cmp    $0x37,%al
  jg     L138
  movsbl 0x1(%rbx),%edx
  sub    $0x30,%eax
  add    $0x4,%rbx
  lea    -0x180(,%rdx,8),%ecx
  movsbl -0x2(%rbx),%edx
  sub    $0x30,%edx
  or     %ecx,%edx
  shl    $0x3,%edx
  or     %edx,%eax
  jmp    L167
  nopw   0x0(%rax,%rax,1)
L133:
  xor    %r13d,%r13d
  jmp    L39
  nopl   0x0(%rax,%rax,1)
L201:
  mov    $0xffffffff,%r13d
  jmp    L116
```

assistant: ```c
int qword_get(char **bpp, char *dest, int bufsize) {
  char *bp = *bpp;
  int len = 0;
  while (*bp == ' ')
    bp++;
  if (bp[0] == '\\' && bp[1] == 'x') {
    bp += 2;
    while (isxdigit(bp[0]) && isxdigit(bp[1]) && len < bufsize) {
      int byte = isdigit(*bp) ? *bp - '0' : toupper(*bp) - 'A' + 10;
      bp++;
      byte <<= 4;
      byte |= isdigit(*bp) ? *bp - '0' : toupper(*bp) - 'A' + 10;
      *dest++ = byte;
      bp++;
      len++;
    }
  } else {
    while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize - 1) {
      if (*bp == '\\' && (isdigit(bp[1]) && bp[1] <= '7') && (bp[1] <= '3') && (isdigit(bp[2]) && bp[2] <= '7') && (isdigit(bp[3]) && bp[3] <= '7')) {
        int byte = (*++bp - '0');
        bp++;
        byte = (byte << 3) | (*bp++ - '0');
        byte = (byte << 3) | (*bp++ - '0');
        *dest++ = byte;
        len++;
      } else {
        *dest++ = *bp++;
        len++;
      }
    }
  }
  if (*bp != ' ' && *bp != '\n' && *bp != '\0')
    return -1;
  while (*bp == ' ')
    bp++;
  *bpp = bp;
  *dest = '\0';
  return len;
}
```