user: 下面的汇编指令对应的C源代码是什么：

```asm
<fgen_copy_partial_bitstring>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x18(%rbp)
  mov    %rsi,-0x20(%rbp)
  mov    %edx,-0x24(%rbp)
  mov    %ecx,-0x28(%rbp)
  cmpl   $0x0,-0x28(%rbp)
  je     L45
  mov    -0x24(%rbp),%eax
  lea    0x7(%rax),%edx
  test   %eax,%eax
  cmovs  %edx,%eax
  sar    $0x3,%eax
  mov    %eax,-0x4(%rbp)
  mov    -0x24(%rbp),%eax
  and    $0x7,%eax
  test   %eax,%eax
  je     L43
  mov    -0x24(%rbp),%eax
  and    $0x7,%eax
  mov    %eax,-0x8(%rbp)
  jmp    L55
L135:
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  mov    %eax,%esi
  mov    -0x8(%rbp),%eax
  mov    $0x1,%edx
  mov    %eax,%ecx
  shl    %cl,%edx
  mov    %edx,%eax
  not    %eax
  and    %eax,%esi
  mov    %esi,%ecx
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  mov    %eax,%esi
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  mov    %eax,%edi
  mov    -0x8(%rbp),%eax
  mov    $0x1,%edx
  mov    %eax,%ecx
  shl    %cl,%edx
  mov    %edx,%eax
  and    %edi,%eax
  or     %eax,%esi
  mov    %esi,%ecx
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  subl   $0x1,-0x28(%rbp)
  cmpl   $0x0,-0x28(%rbp)
  je     L95
  addl   $0x1,-0x8(%rbp)
L55:
  cmpl   $0x7,-0x8(%rbp)
  jle    L135
  addl   $0x1,-0x4(%rbp)
  jmp    L43
L159:
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    -0x4(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x20(%rbp),%rdx
  add    %rcx,%rdx
  movzbl (%rax),%eax
  mov    %al,(%rdx)
  subl   $0x8,-0x28(%rbp)
  addl   $0x1,-0x4(%rbp)
L43:
  cmpl   $0x7,-0x28(%rbp)
  jle    L146
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  and    $0x3,%eax
  test   %eax,%eax
  jne    L159
  jmp    L146
L90:
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    -0x4(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x20(%rbp),%rdx
  add    %rcx,%rdx
  mov    (%rax),%eax
  mov    %eax,(%rdx)
  subl   $0x20,-0x28(%rbp)
  addl   $0x4,-0x4(%rbp)
L146:
  cmpl   $0x1f,-0x28(%rbp)
  jg     L90
  jmp    L88
L91:
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    -0x4(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x20(%rbp),%rdx
  add    %rcx,%rdx
  movzbl (%rax),%eax
  mov    %al,(%rdx)
  subl   $0x8,-0x28(%rbp)
  addl   $0x1,-0x4(%rbp)
L88:
  cmpl   $0x7,-0x28(%rbp)
  jg     L91
  movl   $0x0,-0x8(%rbp)
  jmp    L92
L35:
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  mov    %eax,%esi
  mov    -0x8(%rbp),%eax
  mov    $0x1,%edx
  mov    %eax,%ecx
  shl    %cl,%edx
  mov    %edx,%eax
  not    %eax
  and    %eax,%esi
  mov    %esi,%ecx
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  mov    %eax,%esi
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  mov    %eax,%edi
  mov    -0x8(%rbp),%eax
  mov    $0x1,%edx
  mov    %eax,%ecx
  shl    %cl,%edx
  mov    %edx,%eax
  and    %edi,%eax
  or     %eax,%esi
  mov    %esi,%ecx
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  addl   $0x1,-0x8(%rbp)
L92:
  mov    -0x8(%rbp),%eax
  cmp    -0x28(%rbp),%eax
  jl     L35
  jmp    L154
L45:
  nop
  jmp    L154
L95:
  nop
L154:
  pop    %rbp
  ret
```

assistant: ```c
void fgen_copy_partial_bitstring(const unsigned char *src, unsigned char *dest, int bitoffset, int number_of_bits) {
  int i, offset;
  if (number_of_bits == 0)
    return;
  offset = bitoffset / 8;
  if ((bitoffset & 7) != 0) {
    for (i = bitoffset & 7; i < 8; i++) {
      dest[offset] &= ~(1 << i);
      dest[offset] |= src[offset] & (1 << i);
      number_of_bits--;
      if (number_of_bits == 0)
        return;
    }
    offset++;
  }
  while (number_of_bits >= 8 && (((unsigned int)(&dest[offset])) & 3) != 0) {
    dest[offset] = src[offset];
    number_of_bits -= 8;
    offset++;
  }
  while (number_of_bits >= 32) {
    *(unsigned int *)&dest[offset] = *(unsigned int *)&src[offset];
    number_of_bits -= 32;
    offset += 4;
  }
  while (number_of_bits >= 8) {
    dest[offset] = src[offset];
    number_of_bits -= 8;
    offset++;
  }
  for (i = 0; i < number_of_bits; i++) {
    dest[offset] &= ~(1 << i);
    dest[offset] |= src[offset] & (1 << i);
  }
}
```