user: What would the C source look like for the assembly code provided here?

```asm
<fftkey>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x78,%rsp
  mov    (%rsi),%r12d
  mov    %rdi,0x8(%rsp)
  mov    %rsi,(%rsp)
  mov    %fs:0x28,%rax
  mov    %rax,0x68(%rsp)
  xor    %eax,%eax
  test   %r12d,%r12d
  jg     L139
  mov    %rdi,%r13
  call   <strlen@plt>
  mov    $0x8,%edx
  cmp    %rdx,%rax
  cmovbe %rax,%rdx
  mov    %rdx,%rbx
  test   %rax,%rax
  je     L7
  xor    %ebp,%ebp
  xor    %r15d,%r15d
  jmp    L62
  xchg   %ax,%ax
L121:
  mov    %edi,%r12d
  mov    %rax,%r15
L62:
  movzbl 0x0(%r13),%eax
  mov    %r13,%r14
  xor    %edi,%edi
  test   %r12d,%r12d
  jne    L45
L167:
  sub    $0x2d,%eax
  cmp    $0x32,%al
  ja     L17
  movabs $0xfffbc000000fe006,%rdx
  bt     %rax,%rdx
  jae    L79
L17:
  cmpb   $0x20,0x0(%r13)
  jne    L51
  mov    $0x1,%ebp
L84:
  lea    0x1(%r15),%rax
  cmp    %rax,%rbx
  jbe    L128
  add    $0x1,%r13
  test   %r12d,%r12d
  je     10e0 <fftkey.cold>
  jmp    L121
  nopl   0x0(%rax,%rax,1)
L79:
  test   %ebp,%ebp
  je     L84
  test   %edi,%edi
  je     L175
L49:
  mov    (%rsp),%rax
  mov    $0xcf,%r12d
  movl   $0xcf,(%rax)
L139:
  mov    0x68(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L189
  add    $0x78,%rsp
  mov    %r12d,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  xchg   %ax,%ax
L45:
  movsbl %al,%edi
  call   <toupper@plt>
  mov    (%rsp),%rcx
  mov    (%rcx),%edi
  jmp    L167
L7:
  mov    %r12d,%edi
  cs nopw 0x0(%rax,%rax,1)
L128:
  mov    %edi,%r12d
  jmp    L139
L175:
  lea    0x10(%rsp),%rbp
  mov    0x8(%rsp),%rcx
  lea    D9(%rip),%rdx
  xor    %eax,%eax
  mov    %rbp,%rdi
  mov    $0x51,%esi
  call   <snprintf@plt>
  mov    %rbp,%rdi
  call   <ffpmsg@plt>
  jmp    L49
L51:
  test   %edi,%edi
  jne    L49
  mov    0x8(%rsp),%r8
  lea    0x10(%rsp),%rbp
  lea    0x1(%r15),%ecx
  xor    %eax,%eax
  lea    D24(%rip),%rdx
  mov    $0x51,%esi
  mov    %rbp,%rdi
  call   <snprintf@plt>
  mov    %rbp,%rdi
  call   <ffpmsg@plt>
  movzbl (%r14),%eax
  test   %al,%al
  je     L146
  cmp    $0x9,%al
  jne    L49
  lea    D22(%rip),%rdi
  call   <ffpmsg@plt>
  jmp    L49
L146:
  lea    D29(%rip),%rdi
  call   <ffpmsg@plt>
  jmp    L49
L189:
  call   <__stack_chk_fail@plt>
```

tool_calls: name: parse_data
arguments: data_label: D9
data_type: string
name: parse_data
arguments: data_label: D24
data_type: string
name: parse_data
arguments: data_label: D22
data_type: string
name: parse_data
arguments: data_label: D29
data_type: string

tool: D9: Keyword name contains embedded space(s): %.8s

tool: D24: Character %d in this keyword is illegal: %.8s

tool: D22:  (This an ASCII TAB (9) character).

tool: D29:  (This a NULL (0) character).

assistant: ```c
int fftkey(const char *keyword, int *status) {
  size_t maxchr, ii;
  int spaces = 0;
  char msg[81], testchar;
  if (*status > 0)
    return (*status);
  maxchr = strlen(keyword);
  if (maxchr > 8)
    maxchr = 8;
  for (ii = 0; ii < maxchr; ii++) {
    if (*status == 0)
      testchar = keyword[ii];
    else
      testchar = toupper(keyword[ii]);
    if ((testchar >= 'A' && testchar <= 'Z') || (testchar >= '0' && testchar <= '9') || testchar == '-' || testchar == '_') {
      if (spaces) {
        if (*status == 0) {
          snprintf(msg, 81, "Keyword name contains embedded space(s): %.8s", keyword);
          ffpmsg(msg);
        }
        return (*status = 207);
      }
    } else if (keyword[ii] == ' ')
      spaces = 1;
    else {
      if (*status == 0) {
        snprintf(msg, 81, "Character %d in this keyword is illegal: %.8s", (int)(ii + 1), keyword);
        ffpmsg(msg);
        if (keyword[ii] == 0)
          ffpmsg(" (This a NULL (0) character).");
        else if (keyword[ii] == 9)
          ffpmsg(" (This an ASCII TAB (9) character).");
      }
      return (*status = 207);
    }
  }
  return (*status);
}
```