user: 请将以下的汇编代码转换成C语言代码：

```asm
<deduct>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x18(%rbp)
  mov    %esi,-0x1c(%rbp)
  mov    %rdx,-0x28(%rbp)
  mov    %ecx,-0x20(%rbp)
  mov    -0x1c(%rbp),%eax
  cmp    -0x20(%rbp),%eax
  je     L194
  mov    -0x1c(%rbp),%eax
  mov    %eax,-0xc(%rbp)
  mov    -0x20(%rbp),%eax
  mov    %eax,-0x8(%rbp)
  jmp    L218
L126:
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  mov    -0xc(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x28(%rbp),%rdx
  add    %rcx,%rdx
  movzbl (%rax),%eax
  mov    %al,(%rdx)
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  subl   $0x1,-0xc(%rbp)
  subl   $0x1,-0x8(%rbp)
L218:
  cmpl   $0x0,-0x8(%rbp)
  jns    L126
L194:
  mov    -0x1c(%rbp),%eax
  mov    %eax,-0xc(%rbp)
  jmp    L80
L226:
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%edx
  mov    -0xc(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x28(%rbp),%rax
  add    %rcx,%rax
  movzbl (%rax),%eax
  cmp    %al,%dl
  jb     L95
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%edx
  mov    -0xc(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x28(%rbp),%rax
  add    %rcx,%rax
  movzbl (%rax),%ecx
  mov    -0xc(%rbp),%eax
  movslq %eax,%rsi
  mov    -0x18(%rbp),%rax
  add    %rsi,%rax
  sub    %ecx,%edx
  mov    %dl,(%rax)
  jmp    L40
L95:
  mov    -0xc(%rbp),%eax
  sub    $0x1,%eax
  mov    %eax,-0x8(%rbp)
L22:
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  test   %al,%al
  je     L142
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%edx
  sub    $0x1,%edx
  mov    %dl,(%rax)
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%edx
  mov    -0xc(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x28(%rbp),%rax
  add    %rcx,%rax
  movzbl (%rax),%ecx
  mov    -0xc(%rbp),%eax
  movslq %eax,%rsi
  mov    -0x18(%rbp),%rax
  add    %rsi,%rax
  sub    %ecx,%edx
  mov    %dl,(%rax)
  jmp    L40
L142:
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0xff,(%rax)
  subl   $0x1,-0x8(%rbp)
  jmp    L22
L40:
  subl   $0x1,-0xc(%rbp)
L80:
  cmpl   $0x0,-0xc(%rbp)
  jns    L226
  mov    -0x1c(%rbp),%eax
  cmp    -0x20(%rbp),%eax
  je     L27
  mov    -0x1c(%rbp),%eax
  mov    %eax,-0x20(%rbp)
  movl   $0x0,-0xc(%rbp)
  jmp    L143
L94:
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L200
  movl   $0x0,-0x8(%rbp)
  movl   $0x1,-0x4(%rbp)
  jmp    L19
L37:
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  mov    -0x8(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x28(%rbp),%rdx
  add    %rcx,%rdx
  movzbl (%rax),%eax
  mov    %al,(%rdx)
  addl   $0x1,-0x8(%rbp)
  addl   $0x1,-0x4(%rbp)
L19:
  mov    -0x4(%rbp),%eax
  cmp    -0x20(%rbp),%eax
  jle    L37
  mov    -0x20(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  subl   $0x1,-0x20(%rbp)
  addl   $0x1,-0xc(%rbp)
L143:
  mov    -0xc(%rbp),%eax
  cmp    -0x20(%rbp),%eax
  jle    L94
  jmp    L27
L200:
  nop
L27:
  movl   $0x0,-0xc(%rbp)
  jmp    L179
L11:
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L81
  movl   $0x0,-0x8(%rbp)
  movl   $0x1,-0x4(%rbp)
  jmp    L115
L227:
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    -0x8(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x18(%rbp),%rdx
  add    %rcx,%rdx
  movzbl (%rax),%eax
  mov    %al,(%rdx)
  addl   $0x1,-0x8(%rbp)
  addl   $0x1,-0x4(%rbp)
L115:
  mov    -0x4(%rbp),%eax
  cmp    -0x1c(%rbp),%eax
  jle    L227
  mov    -0x1c(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  subl   $0x1,-0x1c(%rbp)
  addl   $0x1,-0xc(%rbp)
L179:
  mov    -0xc(%rbp),%eax
  cmp    -0x1c(%rbp),%eax
  jle    L11
  jmp    L187
L81:
  nop
L187:
  mov    -0x1c(%rbp),%eax
  pop    %rbp
  ret
```

assistant: ```c
int deduct(unsigned char *a, int a_len, unsigned char *b, int b_len) {
  int i, j, k;
  if (a_len != b_len) {
    for (i = a_len, j = b_len; j >= 0; i--, j--) {
      b[i] = b[j];
      b[j] = 0;
    }
  }
  for (i = a_len; i >= 0; i--) {
    if (a[i] >= b[i])
      a[i] -= b[i];
    else {
      j = i - 1;
      while (1) {
        if (a[j] > 0) {
          a[j]--;
          a[i] += 256 - b[i];
          break;
        } else
          a[j] = 255;
        j--;
      }
    }
  }
  if (a_len != b_len) {
    b_len = a_len;
    for (i = 0; i <= b_len; i++) {
      if (b[i] > 0)
        break;
      else {
        for (j = 0, k = 1; k <= b_len; j++, k++)
          b[j] = b[k];
        b[b_len] = 0;
        b_len--;
      }
    }
  }
  for (i = 0; i <= a_len; i++) {
    if (a[i] > 0)
      break;
    else {
      for (j = 0, k = 1; k <= a_len; j++, k++)
        a[j] = a[k];
      a[a_len] = 0;
      a_len--;
    }
  }
  return a_len;
}
```