user: 请将这段汇编代码片段转换成等效的C代码：

```asm
<main>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x90,%rsp
  mov    %edi,-0x84(%rbp)
  mov    %rsi,-0x90(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  cmpl   $0x2,-0x84(%rbp)
  jne    L37
  mov    -0x90(%rbp),%rax
  add    $0x8,%rax
  mov    (%rax),%rax
  mov    %rax,%rdi
  call   <atoi@plt>
  mov    %eax,-0x74(%rbp)
  lea    D26(%rip),%rax
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <printf@plt>
  lea    -0x70(%rbp),%rax
  mov    %rax,%rsi
  lea    D25(%rip),%rax
  mov    %rax,%rdi
  call   <scanf@plt>
  lea    D14(%rip),%rax
  mov    %rax,%rdi
  call   <puts@plt>
  movl   $0x0,-0x78(%rbp)
  jmp    L64
L57:
  mov    -0x78(%rbp),%eax
  cltq
  movzbl -0x70(%rbp,%rax,1),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isalpha@plt>
  test   %rax,%rax
  je     L30
  mov    -0x78(%rbp),%eax
  cltq
  movzbl -0x70(%rbp,%rax,1),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isupper@plt>
  test   %rax,%rax
  je     L77
  mov    -0x78(%rbp),%eax
  cltq
  movzbl -0x70(%rbp,%rax,1),%eax
  movsbl %al,%eax
  lea    -0x41(%rax),%edx
  mov    -0x74(%rbp),%eax
  add    %eax,%edx
  movslq %edx,%rax
  imul   $0x4ec4ec4f,%rax,%rax
  shr    $0x20,%rax
  sar    $0x3,%eax
  mov    %edx,%ecx
  sar    $0x1f,%ecx
  sub    %ecx,%eax
  imul   $0x1a,%eax,%ecx
  mov    %edx,%eax
  sub    %ecx,%eax
  add    $0x41,%eax
  mov    %eax,%edi
  call   <putchar@plt>
L77:
  mov    -0x78(%rbp),%eax
  cltq
  movzbl -0x70(%rbp,%rax,1),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <islower@plt>
  test   %rax,%rax
  je     L15
  mov    -0x78(%rbp),%eax
  cltq
  movzbl -0x70(%rbp,%rax,1),%eax
  movsbl %al,%eax
  lea    -0x61(%rax),%edx
  mov    -0x74(%rbp),%eax
  add    %eax,%edx
  movslq %edx,%rax
  imul   $0x4ec4ec4f,%rax,%rax
  shr    $0x20,%rax
  sar    $0x3,%eax
  mov    %edx,%ecx
  sar    $0x1f,%ecx
  sub    %ecx,%eax
  imul   $0x1a,%eax,%ecx
  mov    %edx,%eax
  sub    %ecx,%eax
  add    $0x61,%eax
  mov    %eax,%edi
  call   <putchar@plt>
  jmp    L15
L30:
  mov    -0x78(%rbp),%eax
  cltq
  movzbl -0x70(%rbp,%rax,1),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <putchar@plt>
L15:
  addl   $0x1,-0x78(%rbp)
L64:
  lea    -0x70(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  cmp    %eax,-0x78(%rbp)
  jl     L57
  mov    $0xa,%edi
  call   <putchar@plt>
  mov    $0x0,%eax
  jmp    L42
L37:
  lea    D17(%rip),%rax
  mov    %rax,%rdi
  call   <puts@plt>
  mov    $0x1,%eax
L42:
  mov    -0x8(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L14
  call   <__stack_chk_fail@plt>
L14:
  leave
  ret
```

tool_calls: name: parse_data
arguments: data_tag: D26
datatype: string
name: parse_data
arguments: data_tag: D25
datatype: string
name: parse_data
arguments: data_tag: D14
datatype: string
name: parse_data
arguments: data_tag: D17
datatype: string

tool: D26: plaintext: 

tool: D25: %s

tool: D14: ciphertext: 

tool: D17: Invalid key Entered.

assistant: ```c
int main(int argc, char *argv[]) {
  if (argc == 2) {
    int r = atoi(argv[1]);
    printf("plaintext: ");
    char s[100];
    scanf("%s", s);
    printf("ciphertext: \n");
    for (int i = 0; i < strlen(s); i++) {
      if (isalpha(s[i])) {
        if (isupper(s[i])) {
          printf("%c", ((s[i] - 65 + r) % 26) + 65);
        }
        if (islower(s[i])) {
          printf("%c", ((s[i] - 97 + r) % 26) + 97);
        }
      } else
        printf("%c", s[i]);
    }
    printf("\n");
    return 0;
  } else {
    printf("Invalid key Entered.\n");
    return 1;
  }
}
```