user: Converte this assembly snippet into its equivalent C code:

```asm
<subtractone>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x40,%rsp
  mov    %rdi,-0x38(%rbp)
  cmpq   $0x0,-0x38(%rbp)
  jne    L71
  mov    $0x0,%eax
  jmp    L123
L71:
  mov    -0x38(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %eax,-0x10(%rbp)
  mov    -0x10(%rbp),%eax
  mov    %eax,-0xc(%rbp)
  mov    -0xc(%rbp),%eax
  add    $0x1,%eax
  mov    $0x1,%esi
  mov    %eax,%edi
  call   <calloc@plt>
  mov    %rax,-0x8(%rbp)
  movl   $0x0,-0x24(%rbp)
  movl   $0x0,-0x20(%rbp)
  movl   $0x0,-0x28(%rbp)
  movl   $0x0,-0x1c(%rbp)
  mov    -0xc(%rbp),%eax
  mov    %eax,-0x2c(%rbp)
  jmp    L23
L97:
  mov    -0x10(%rbp),%eax
  sub    -0x28(%rbp),%eax
  test   %eax,%eax
  jns    L146
  movl   $0x0,-0x1c(%rbp)
  jmp    L111
L146:
  mov    -0x10(%rbp),%eax
  sub    -0x28(%rbp),%eax
  cltq
  lea    -0x1(%rax),%rdx
  mov    -0x38(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  sub    $0x30,%eax
  mov    %eax,-0x1c(%rbp)
L111:
  cmpl   $0x0,-0x1c(%rbp)
  jns    L61
  movl   $0x0,-0x1c(%rbp)
L61:
  mov    -0x2c(%rbp),%eax
  cmp    -0xc(%rbp),%eax
  jne    L161
  mov    -0x1c(%rbp),%eax
  add    $0x2f,%eax
  mov    %eax,-0x20(%rbp)
  jmp    L119
L161:
  mov    -0x1c(%rbp),%eax
  add    $0x30,%eax
  mov    %eax,-0x20(%rbp)
L119:
  cmpl   $0x1,-0x24(%rbp)
  jne    L4
  subl   $0x1,-0x20(%rbp)
L4:
  cmpl   $0x2f,-0x20(%rbp)
  jg     L26
  movl   $0x1,-0x24(%rbp)
  addl   $0xa,-0x20(%rbp)
  jmp    L96
L26:
  movl   $0x0,-0x24(%rbp)
L96:
  mov    -0x2c(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  mov    -0x20(%rbp),%edx
  mov    %dl,(%rax)
  addl   $0x1,-0x28(%rbp)
  subl   $0x1,-0x2c(%rbp)
L23:
  cmpl   $0x0,-0x2c(%rbp)
  jns    L97
  mov    -0xc(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  movl   $0x0,-0x18(%rbp)
  jmp    L31
L155:
  addl   $0x1,-0x18(%rbp)
L31:
  mov    -0x18(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  cmp    $0x30,%al
  je     L155
  cmpl   $0x0,-0x18(%rbp)
  jle    L35
  movl   $0x0,-0x14(%rbp)
  jmp    L10
L17:
  mov    -0x14(%rbp),%edx
  mov    -0x18(%rbp),%eax
  add    %edx,%eax
  movslq %eax,%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  mov    -0x14(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x8(%rbp),%rdx
  add    %rcx,%rdx
  movzbl (%rax),%eax
  mov    %al,(%rdx)
  addl   $0x1,-0x14(%rbp)
L10:
  mov    -0x8(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  cmp    %eax,-0x14(%rbp)
  jl     L17
L35:
  mov    -0x8(%rbp),%rax
L123:
  leave
  ret
```

assistant: ```c
char *subtractone(char *num1) {
  int i, j;
  if (num1 == NULL) {
    return NULL;
  }
  int lennum1 = strlen(num1);
  int hook = lennum1;
  char *newnum = calloc(hook + 1, sizeof(char));
  int noted = 0;
  int temp = 0;
  j = 0;
  int currnum1 = 0;
  for (i = hook; i >= 0; i--) {
    if ((lennum1 - j) < 0) {
      currnum1 = 0;
    } else {
      currnum1 = (int)num1[lennum1 - j - 1] - 48;
    }
    if (currnum1 < 0) {
      currnum1 = 0;
    }
    if (i == hook) {
      temp = (currnum1 - 1) + 48;
    } else {
      temp = currnum1 + 48;
    }
    if (noted == 1) {
      temp--;
    }
    if (temp < 48) {
      noted = 1;
      temp = temp + 10;
    } else {
      noted = 0;
    }
    *(newnum + i) = (char)temp;
    j++;
  }
  newnum[hook + 1] = '\0';
  int zerooffset = 0;
  while (newnum[zerooffset] == '0') {
    zerooffset++;
  }
  if (zerooffset > 0) {
    int l;
    for (l = 0; l < strlen(newnum); l++) {
      newnum[l] = newnum[l + zerooffset];
    }
  }
  return newnum;
}
```