user: 这段汇编代码用C语言表示是什么样的？

```asm
<pftoa>:
  endbr64
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x18,%rsp
  mov    %rdi,%rbp
  mov    %fs:0x28,%rax
  mov    %rax,0x8(%rsp)
  xor    %eax,%eax
  movd   %xmm0,%eax
  movd   %xmm0,%ecx
  shr    $0x10,%ecx
  and    $0x7f,%ecx
  shr    $0x17,%eax
  sub    $0x7f,%eax
  cmp    $0x12,%al
  jg     L189
  movd   %xmm0,%edx
  cmp    $0xfd,%al
  jl     L151
  movd   %xmm0,%esi
  shr    $0x18,%esi
  mov    $0x0,%r12d
  test   %sil,%sil
  js     L192
L172:
  movzwl %dx,%edx
  movzbl %cl,%ecx
  shl    $0x10,%rcx
  lea    0x800000(%rdx,%rcx,1),%r13
  movsbl %al,%ebx
  movslq %r12d,%rsi
  add    %rbp,%rsi
  mov    $0x17,%ecx
  sub    %ebx,%ecx
  mov    $0xa,%edx
  mov    %r13,%rax
  shr    %cl,%rax
  mov    %rax,%rdi
  call   <itoa@plt>
  mov    $0x0,%eax
L122:
  cmpb   $0x0,0x0(%rbp,%rax,1)
  je     L15
  add    $0x1,%rax
  cmp    $0x8,%rax
  jne    L122
L210:
  lea    0x1(%r12),%edx
  movslq %r12d,%r12
  movb   $0x2e,0x0(%rbp,%r12,1)
  mov    $0x14,%ecx
  sub    %ebx,%ecx
  shr    %cl,%r13
  and    $0x7,%r13d
  lea    D7(%rip),%rcx
  movslq (%rcx,%r13,4),%rax
  add    %rcx,%rax
  notrack jmp *%rax
L189:
  movb   $0x49,(%rdi)
  movb   $0x6e,0x1(%rdi)
  movb   $0x66,0x2(%rdi)
  movb   $0x0,0x3(%rdi)
L89:
  mov    0x8(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L188
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
L151:
  movb   $0x30,(%rdi)
  movb   $0x0,0x1(%rdi)
  jmp    L89
L192:
  movb   $0x2d,(%rdi)
  mov    $0x1,%r12d
  jmp    L172
L15:
  cmp    $0x5,%eax
  jg     L89
  mov    %eax,%r12d
  jmp    L210
  movb   $0x30,0x5(%rsp)
  movb   $0x30,0x6(%rsp)
  movb   $0x30,0x7(%rsp)
L102:
  lea    0x5(%rsp),%rax
  lea    0x8(%rsp),%rcx
  jmp    L17
  movb   $0x31,0x5(%rsp)
  movb   $0x32,0x6(%rsp)
  movb   $0x35,0x7(%rsp)
  jmp    L102
  movb   $0x32,0x5(%rsp)
  movb   $0x35,0x6(%rsp)
  movb   $0x30,0x7(%rsp)
  jmp    L102
  movb   $0x33,0x5(%rsp)
  movb   $0x37,0x6(%rsp)
  movb   $0x35,0x7(%rsp)
  jmp    L102
  movb   $0x35,0x5(%rsp)
  movb   $0x30,0x6(%rsp)
  movb   $0x30,0x7(%rsp)
  jmp    L102
  movb   $0x36,0x5(%rsp)
  movb   $0x32,0x6(%rsp)
  movb   $0x35,0x7(%rsp)
  jmp    L102
  movb   $0x37,0x5(%rsp)
  movb   $0x35,0x6(%rsp)
  movb   $0x30,0x7(%rsp)
  jmp    L102
  movb   $0x38,0x5(%rsp)
  movb   $0x37,0x6(%rsp)
  movb   $0x35,0x7(%rsp)
  jmp    L102
L112:
  add    $0x1,%rax
  cmp    %rax,%rcx
  je     L173
L17:
  cmp    $0x6,%edx
  jg     L112
  movslq %edx,%rsi
  movzbl (%rax),%edi
  mov    %dil,0x0(%rbp,%rsi,1)
  lea    0x1(%rdx),%edx
  jmp    L112
L173:
  movslq %edx,%rdx
  movb   $0x0,0x0(%rbp,%rdx,1)
  jmp    L89
L188:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void pftoa(float value, char *buffer) {
  union {
    float f;
    struct {
      unsigned int mantissa_lo : 16;
      unsigned int mantissa_hi : 7;
      unsigned int exponent : 8;
      unsigned int sign : 1;
    };
  } helper;
  unsigned long mantissa;
  signed char exponent;
  unsigned int int_part;
  char frac_part[3];
  int i, count = 0;
  helper.f = value;
  mantissa = helper.mantissa_lo;
  mantissa += ((unsigned long)helper.mantissa_hi << 16);
  mantissa += 0x00800000;
  exponent = (signed char)helper.exponent - 127;
  if (exponent > 18) {
    buffer[0] = 'I';
    buffer[1] = 'n';
    buffer[2] = 'f';
    buffer[3] = '\0';
    return;
  }
  if (exponent < -3) {
    buffer[0] = '0';
    buffer[1] = '\0';
    return;
  }
  count = 0;
  if (helper.sign) {
    buffer[0] = '-';
    count++;
  }
  int_part = mantissa >> (23 - exponent);
  itoa(int_part, &buffer[count], 10);
  for (i = 0; i < 8; i++)
    if (buffer[i] == '\0') {
      count = i;
      break;
    }
  if (count > 5)
    return;
  buffer[count++] = '.';
  switch (0x7 & (mantissa >> (20 - exponent))) {
  case 0:
    frac_part[0] = '0';
    frac_part[1] = '0';
    frac_part[2] = '0';
    break;
  case 1:
    frac_part[0] = '1';
    frac_part[1] = '2';
    frac_part[2] = '5';
    break;
  case 2:
    frac_part[0] = '2';
    frac_part[1] = '5';
    frac_part[2] = '0';
    break;
  case 3:
    frac_part[0] = '3';
    frac_part[1] = '7';
    frac_part[2] = '5';
    break;
  case 4:
    frac_part[0] = '5';
    frac_part[1] = '0';
    frac_part[2] = '0';
    break;
  case 5:
    frac_part[0] = '6';
    frac_part[1] = '2';
    frac_part[2] = '5';
    break;
  case 6:
    frac_part[0] = '7';
    frac_part[1] = '5';
    frac_part[2] = '0';
    break;
  case 7:
    frac_part[0] = '8';
    frac_part[1] = '7';
    frac_part[2] = '5';
    break;
  }
  for (i = 0; i < 3; i++)
    if (count < 7)
      buffer[count++] = frac_part[i];
  buffer[count] = '\0';
}
```