user: 请将以下的汇编代码转换成C语言代码：

```asm
<deduct>:
  endbr64
  push   %r14
  push   %r13
  mov    %rdi,%r13
  mov    %rdx,%rdi
  push   %r12
  push   %rbp
  mov    %esi,%ebp
  push   %rbx
  movslq %ecx,%rbx
  cmp    %ebx,%esi
  je     L202
  test   %ebx,%ebx
  js     L202
  movslq %ebx,%r8
  movslq %esi,%rax
  lea    -0x1(%rdi,%r8,1),%r9
  lea    (%rdx,%r8,1),%rdx
  sub    %r8,%r9
  nopl   0x0(%rax)
L9:
  movzbl (%rdx),%esi
  mov    %rdx,%rcx
  sub    $0x1,%rdx
  sub    %r8,%rcx
  mov    %sil,(%rcx,%rax,1)
  movb   $0x0,0x1(%rdx)
  cmp    %rdx,%r9
  jne    L9
L202:
  mov    %ebp,%r10d
  test   %ebp,%ebp
  js     L114
  movslq %ebp,%rax
  lea    (%rdi,%rax,1),%r9
  lea    -0x1(%r13,%rax,1),%r8
  jmp    L100
  nopl   0x0(%rax,%rax,1)
L60:
  sub    %ecx,%edx
L5:
  mov    %dl,0x1(%r8)
  sub    $0x1,%r9
  sub    $0x1,%r8
  cmp    $0xffffffff,%r10d
  je     L87
L100:
  movzbl 0x1(%r8),%edx
  movzbl (%r9),%ecx
  sub    $0x1,%r10d
  cmp    %cl,%dl
  jae    L60
  movzbl (%r8),%ecx
  test   %cl,%cl
  jne    L41
  movslq %r10d,%rdx
  mov    %r8,%rsi
  lea    -0x1(%r13,%rdx,1),%rdx
  nopl   0x0(%rax)
L208:
  movb   $0xff,(%rsi)
  mov    %rdx,%rsi
  movzbl (%rdx),%ecx
  sub    $0x1,%rdx
  test   %cl,%cl
  je     L208
  sub    $0x1,%ecx
  mov    %cl,(%rsi)
  movzbl 0x1(%r8),%edx
  sub    (%r9),%dl
  jmp    L5
L162:
  movb   $0x0,0x0(%r13,%rbx,1)
  add    $0x1,%r12
  sub    $0x1,%rbx
  sub    $0x1,%ebp
  cmp    %r12d,%ebx
  jge    L157
L114:
  pop    %rbx
  mov    %ebp,%eax
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  ret
  nopl   0x0(%rax)
L87:
  cmp    %ebx,%ebp
  je     L110
  test   %ebp,%ebp
  js     L114
  mov    %rax,%rbx
  xor    %r12d,%r12d
  lea    0x1(%rdi),%r14
  xchg   %ax,%ax
L82:
  cmpb   $0x0,(%rdi,%r12,1)
  jne    L174
  test   %ebx,%ebx
  jle    L24
  lea    -0x1(%rbx),%edx
  mov    %r14,%rsi
  add    $0x1,%rdx
  call   <memmove@plt>
  mov    %rax,%rdi
L24:
  movb   $0x0,(%rdi,%rbx,1)
  add    $0x1,%r12
  sub    $0x1,%rbx
  cmp    %r12d,%ebx
  jge    L82
L174:
  movslq %ebp,%rbx
L98:
  xor    %r12d,%r12d
  lea    0x1(%r13),%r14
  nopl   0x0(%rax,%rax,1)
L157:
  cmpb   $0x0,0x0(%r13,%r12,1)
  mov    %ebx,%ebp
  jne    L114
  test   %ebx,%ebx
  jle    L162
  lea    -0x1(%rbx),%edx
  mov    %r14,%rsi
  mov    %r13,%rdi
  add    $0x1,%r12
  mov    %rdx,%rbp
  add    $0x1,%rdx
  call   <memmove@plt>
  movb   $0x0,0x0(%r13,%rbx,1)
  sub    $0x1,%rbx
  cmp    %r12d,%ebx
  jge    L157
  pop    %rbx
  mov    %ebp,%eax
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  ret
L110:
  test   %ebp,%ebp
  jns    L98
  jmp    L114
  xchg   %ax,%ax
L41:
  mov    %r8,%rsi
  sub    $0x1,%ecx
  mov    %cl,(%rsi)
  movzbl 0x1(%r8),%edx
  sub    (%r9),%dl
  jmp    L5
```

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;
}
```