user: 请显示与下面列出的汇编代码相匹配的C语言实现：

```asm
<expand>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x18,%rsp
  mov    %rdi,%r12
  mov    %rsi,%r13
  mov    %rdi,%rbx
  mov    $0x0,%ebp
  jmp    L158
L94:
  add    $0x1,%ebp
L158:
  mov    %rbx,%r14
  movsbl (%rbx),%edi
  call   <isspace@plt>
  add    $0x1,%rbx
  test   %rax,%rax
  jne    L94
  cmpb   $0x2d,(%r14)
  jne    L90
  movslq %ebp,%rax
  lea    0x1(%r12,%rax,1),%rcx
  mov    %rcx,%rax
  lea    0x1(%rbp),%edx
  sub    %ecx,%edx
L81:
  lea    (%rdx,%rax,1),%ebp
  mov    %rax,%r14
  add    $0x1,%rax
  cmpb   $0x2d,-0x1(%rax)
  je     L81
L90:
  mov    %r12,%rdi
  call   <strlen@plt>
  lea    -0x1(%rax),%ebx
  movslq %ebx,%rbx
L101:
  mov    %ebx,0xc(%rsp)
  lea    (%r12,%rbx,1),%r15
  movsbl (%r12,%rbx,1),%edi
  call   <isspace@plt>
  mov    %rbx,%rdx
  sub    $0x1,%rbx
  test   %rax,%rax
  jne    L101
  cmpb   $0x2d,(%r15)
  jne    L179
  mov    0xc(%rsp),%eax
  sub    $0x1,%eax
  cltq
L9:
  mov    %rax,%rdx
  sub    $0x1,%rax
  cmpb   $0x2d,0x1(%r12,%rax,1)
  je     L9
L179:
  movb   $0x0,0x1(%r12,%rdx,1)
  add    $0x1,%ebp
  movzbl (%r14),%r14d
  movslq %ebp,%rbx
  add    %r12,%rbx
  movzbl (%rbx),%edi
  test   %dil,%dil
  je     L29
  mov    $0x0,%r15d
  jmp    L106
L86:
  lea    0x1(%rbp),%ebx
  movslq %ebx,%rbx
  add    %r12,%rbx
  movsbl (%rbx),%edi
  call   <isalnum@plt>
  test   %rax,%rax
  je     L15
  movzbl (%rbx),%eax
  cmp    %r14b,%al
  jle    L170
  lea    0x1(%r15),%eax
  cltq
  mov    %r14d,%edx
L113:
  mov    %eax,%r15d
  mov    %dl,-0x1(%r13,%rax,1)
  add    $0x1,%edx
  movzbl (%rbx),%r14d
  add    $0x1,%rax
  cmp    %dl,%r14b
  jg     L113
L152:
  add    $0x2,%ebp
L62:
  movslq %ebp,%rbx
  add    %r12,%rbx
  movzbl (%rbx),%edi
  test   %dil,%dil
  je     L183
L106:
  cmp    $0x2d,%dil
  je     L86
  movsbl %dil,%edi
  call   <isalnum@plt>
  test   %rax,%rax
  je     L91
  movslq %r15d,%rax
  mov    %r14b,0x0(%r13,%rax,1)
  add    $0x1,%ebp
  movzbl (%rbx),%r14d
  lea    0x1(%r15),%r15d
  jmp    L62
L170:
  mov    %eax,%r14d
  jmp    L152
L29:
  mov    $0x0,%r15d
L183:
  movslq %r15d,%rax
  mov    %r14b,0x0(%r13,%rax,1)
  add    $0x1,%r15d
  movslq %r15d,%r15
  movb   $0x0,0x0(%r13,%r15,1)
  mov    $0x0,%eax
L0:
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L15:
  mov    $0xffffffff,%eax
  jmp    L0
L91:
  mov    $0xffffffff,%eax
  jmp    L0
```

assistant: ```c
int expand(char s1[], char s2[]) {
  int i, j;
  char ch;
  i = 0;
  while (isspace(s1[i])) {
    i++;
  }
  while (s1[i] == '-') {
    i++;
  }
  int len = strlen(s1) - 1;
  while (isspace(s1[len])) {
    len--;
  }
  while (s1[len] == '-') {
    len--;
  }
  s1[len + 1] = '\0';
  j = 0;
  char start = s1[i++];
  while (s1[i] != '\0') {
    if (s1[i] == '-') {
      i++;
      if (isalnum(s1[i])) {
        for (ch = start; ch < s1[i]; ch++) {
          s2[j++] = ch;
        }
        start = s1[i++];
      } else {
        return -1;
      }
    } else if (isalnum(s1[i])) {
      s2[j++] = start;
      start = s1[i++];
    } else {
      return -1;
    }
  }
  s2[j++] = start;
  s2[j] = '\0';
  return 0;
}
```