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

```asm
<expand>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x30,%rsp
  mov    %rdi,-0x28(%rbp)
  mov    %rsi,-0x30(%rbp)
  movl   $0x0,-0x10(%rbp)
  mov    -0x10(%rbp),%eax
  mov    %eax,-0x14(%rbp)
  movl   $0x0,-0x8(%rbp)
  movl   $0x0,-0x4(%rbp)
  jmp    L88
L13:
  mov    -0x14(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  cmp    $0x2d,%al
  jne    L25
  cmpl   $0x0,-0x14(%rbp)
  je     L146
  mov    -0x14(%rbp),%eax
  cltq
  lea    -0x1(%rax),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  add    $0x1,%eax
  mov    %eax,-0x8(%rbp)
  jmp    L177
L146:
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L26
  movl   $0x30,-0x8(%rbp)
  jmp    L177
L26:
  mov    -0x4(%rbp),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <islower@plt>
  test   %rax,%rax
  je     L29
  movl   $0x61,-0x8(%rbp)
  jmp    L177
L29:
  movl   $0x41,-0x8(%rbp)
L177:
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  test   %al,%al
  je     L166
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  sub    $0x1,%eax
  mov    %eax,-0x4(%rbp)
  jmp    L90
L166:
  mov    -0x14(%rbp),%eax
  cltq
  lea    -0x1(%rax),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L18
  movl   $0x39,-0x4(%rbp)
  jmp    L90
L18:
  mov    -0x14(%rbp),%eax
  cltq
  lea    -0x1(%rax),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <islower@plt>
  test   %rax,%rax
  je     L122
  movl   $0x7a,-0x4(%rbp)
  jmp    L90
L122:
  movl   $0x5a,-0x4(%rbp)
L90:
  mov    -0x8(%rbp),%eax
  mov    %eax,-0xc(%rbp)
  jmp    L94
L32:
  mov    -0x10(%rbp),%eax
  lea    0x1(%rax),%edx
  mov    %edx,-0x10(%rbp)
  movslq %eax,%rdx
  mov    -0x30(%rbp),%rax
  add    %rdx,%rax
  mov    -0xc(%rbp),%edx
  mov    %dl,(%rax)
  addl   $0x1,-0xc(%rbp)
L94:
  mov    -0xc(%rbp),%eax
  cmp    -0x4(%rbp),%eax
  jle    L32
  jmp    L138
L25:
  mov    -0x14(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x28(%rbp),%rax
  lea    (%rdx,%rax,1),%rcx
  mov    -0x10(%rbp),%eax
  lea    0x1(%rax),%edx
  mov    %edx,-0x10(%rbp)
  movslq %eax,%rdx
  mov    -0x30(%rbp),%rax
  add    %rax,%rdx
  movzbl (%rcx),%eax
  mov    %al,(%rdx)
L138:
  addl   $0x1,-0x14(%rbp)
L88:
  mov    -0x14(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L13
  mov    -0x10(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x30(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  nop
  leave
  ret
```

assistant: ```c
void expand(char *s1, char *s2) {
  int i, j, k;
  i = j = 0;
  int min = 0, max = 0;
  for (; s1[i] != '\0'; i++) {
    if (s1[i] == '-') {
      if (i != 0) {
        min = s1[i - 1] + 1;
      } else {
        max = s1[i + 1];
        if (isdigit(max)) {
          min = '0';
        } else if (islower(max)) {
          min = 'a';
        } else {
          min = 'A';
        }
      }
      if (s1[i + 1] != '\0') {
        max = s1[i + 1] - 1;
      } else {
        if (isdigit(s1[i - 1])) {
          max = '9';
        } else if (islower(s1[i - 1])) {
          max = 'z';
        } else {
          max = 'Z';
        }
      }
      for (k = min; k <= max; k++) {
        s2[j++] = k;
      }
    } else {
      s2[j++] = s1[i];
    }
  }
  s2[j] = '\0';
}
```