user: What is the c source code of the assembly code below:

```asm
<process_gre_pptp>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x40,%rsp
  mov    %rdi,-0x28(%rbp)
  mov    %rsi,-0x30(%rbp)
  mov    %rdx,-0x38(%rbp)
  mov    %ecx,-0x3c(%rbp)
  mov    -0x38(%rbp),%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x8,%eax
  mov    %eax,%edx
  mov    -0x38(%rbp),%rax
  add    $0x1,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %edx,%eax
  mov    %eax,-0x14(%rbp)
  mov    -0x38(%rbp),%rax
  add    $0x4,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x8,%eax
  mov    %eax,%edx
  mov    -0x38(%rbp),%rax
  add    $0x5,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %edx,%eax
  mov    %eax,-0x10(%rbp)
  mov    -0x38(%rbp),%rax
  add    $0x6,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x8,%eax
  mov    %eax,%edx
  mov    -0x38(%rbp),%rax
  add    $0x7,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %edx,%eax
  mov    %eax,-0xc(%rbp)
  mov    -0x14(%rbp),%eax
  and    $0xe80f,%eax
  cmp    $0x2001,%eax
  je     L29
  mov    -0x14(%rbp),%ecx
  mov    -0x14(%rbp),%edx
  mov    -0x30(%rbp),%rax
  mov    %ecx,%r8d
  mov    %edx,%ecx
  lea    D13(%rip),%rdx
  lea    D29(%rip),%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <FRAMERR@plt>
  jmp    L42
L29:
  movl   $0x8,-0x18(%rbp)
  mov    -0x14(%rbp),%eax
  and    $0x1000,%eax
  test   %eax,%eax
  je     L24
  mov    -0x18(%rbp),%edx
  mov    -0x38(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x18,%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%eax
  lea    0x1(%rax),%rcx
  mov    -0x38(%rbp),%rax
  add    %rcx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x10,%eax
  or     %eax,%edx
  mov    -0x18(%rbp),%eax
  lea    0x2(%rax),%rcx
  mov    -0x38(%rbp),%rax
  add    %rcx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x8,%eax
  or     %eax,%edx
  mov    -0x18(%rbp),%eax
  lea    0x3(%rax),%rcx
  mov    -0x38(%rbp),%rax
  add    %rcx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %edx,%eax
  mov    %eax,-0x8(%rbp)
  addl   $0x4,-0x18(%rbp)
L24:
  mov    -0x14(%rbp),%eax
  and    $0x80,%eax
  test   %eax,%eax
  je     L46
  mov    -0x18(%rbp),%edx
  mov    -0x38(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x18,%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%eax
  lea    0x1(%rax),%rcx
  mov    -0x38(%rbp),%rax
  add    %rcx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x10,%eax
  or     %eax,%edx
  mov    -0x18(%rbp),%eax
  lea    0x2(%rax),%rcx
  mov    -0x38(%rbp),%rax
  add    %rcx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x8,%eax
  or     %eax,%edx
  mov    -0x18(%rbp),%eax
  lea    0x3(%rax),%rcx
  mov    -0x38(%rbp),%rax
  add    %rcx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %edx,%eax
  mov    %eax,-0x4(%rbp)
  addl   $0x4,-0x18(%rbp)
L46:
  mov    -0x18(%rbp),%eax
  cmp    -0x3c(%rbp),%eax
  jb     L35
  mov    -0x30(%rbp),%rax
  lea    D13(%rip),%rdx
  lea    D23(%rip),%rcx
  mov    %rcx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <FRAMERR@plt>
  jmp    L42
L35:
  mov    -0x3c(%rbp),%eax
  sub    -0x18(%rbp),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%ecx
  mov    -0x38(%rbp),%rax
  lea    (%rcx,%rax,1),%rdi
  mov    -0x30(%rbp),%rsi
  mov    -0x28(%rbp),%rax
  mov    %edx,%ecx
  mov    %rdi,%rdx
  mov    %rax,%rdi
  call   <process_pptp@plt>
L42:
  leave
  ret
```

tool_calls: name: read_data
arguments: data_tag: D13
type_infered: string
name: read_data
arguments: data_tag: D29
type_infered: string
name: read_data
arguments: data_tag: D23
type_infered: string

tool: D13: gre

tool: D29: %s: unknown value: 0x%x (%d)


tool: D23: %s: truncated


assistant: ```c
void process_gre_pptp(struct Seaper *seap, struct NetFrame *frame, const unsigned char *px, unsigned length) {
  unsigned flags;
  unsigned offset;
  unsigned payload_length;
  unsigned call_id;
  unsigned sequence_number;
  unsigned acknowledgement_number;
  flags = (*((unsigned char *)(px) + 0) << 8 | *((unsigned char *)(px) + 1) << 0);
  payload_length = (*((unsigned char *)(px + 4) + 0) << 8 | *((unsigned char *)(px + 4) + 1) << 0);
  call_id = (*((unsigned char *)(px + 6) + 0) << 8 | *((unsigned char *)(px + 6) + 1) << 0);
  if ((flags & 0xE80F) != 0x2001) {
    FRAMERR(frame, "%s: unknown value: 0x%x (%d)\n", "gre", flags, flags);
    ;
    return;
  }
  offset = 8;
  if (flags & 0x1000) {
    sequence_number = (*((unsigned char *)(px + offset) + 0) << 24 | *((unsigned char *)(px + offset) + 1) << 16 | *((unsigned char *)(px + offset) + 2) << 8 | *((unsigned char *)(px + offset) + 3) << 0);
    offset += 4;
  }
  if (flags & 0x0080) {
    acknowledgement_number = (*((unsigned char *)(px + offset) + 0) << 24 | *((unsigned char *)(px + offset) + 1) << 16 | *((unsigned char *)(px + offset) + 2) << 8 | *((unsigned char *)(px + offset) + 3) << 0);
    offset += 4;
  }
  if (offset >= length) {
    FRAMERR(frame, "%s: truncated\n", "gre");
    ;
    return;
  }
  process_pptp(seap, frame, px + offset, length - offset);
}
```