user: 请显示与下面列出的汇编代码相匹配的C语言实现：

```asm
<btff_memmove>:
  endbr64
  mov    %rdi,%rcx
  mov    %rdi,%rax
  or     %rsi,%rcx
  and    $0x3,%ecx
  je     L124
L157:
  cmp    %rsi,%rax
  jae    L141
L129:
  mov    %edx,%edi
  sub    $0x1,%edi
  js     L297
  lea    0x1(%rsi),%r8
  mov    %rax,%rcx
  mov    %edx,%r9d
  mov    %edi,%r10d
  sub    %r8,%rcx
  cmp    $0xe,%rcx
  jbe    L152
  cmp    $0x6,%edi
  jbe    L152
  push   %rbx
  cmp    $0xe,%edi
  jbe    L179
  mov    %edx,%r8d
  xor    %ecx,%ecx
  shr    $0x4,%r8d
  shl    $0x4,%r8
  nopl   0x0(%rax)
L169:
  movdqu (%rsi,%rcx,1),%xmm0
  movups %xmm0,(%rax,%rcx,1)
  add    $0x10,%rcx
  cmp    %rcx,%r8
  jne    L169
  mov    %edx,%ebx
  and    $0xfffffff0,%ebx
  mov    %ebx,%r11d
  sub    %ebx,%edi
  lea    (%rax,%r11,1),%rcx
  lea    (%rsi,%r11,1),%r8
  cmp    %ebx,%edx
  je     L294
  sub    %ebx,%edx
  mov    %edx,%r9d
  lea    -0x1(%rdx),%edx
  cmp    $0x6,%edx
  jbe    L242
L194:
  mov    (%rsi,%r11,1),%rdx
  mov    %rdx,(%rax,%r11,1)
  mov    %r9d,%edx
  and    $0xfffffff8,%edx
  mov    %edx,%esi
  sub    %edx,%edi
  add    %rsi,%rcx
  add    %rsi,%r8
  cmp    %edx,%r9d
  je     L294
L242:
  movzbl (%r8),%edx
  mov    %dl,(%rcx)
  test   %edi,%edi
  je     L294
  movzbl 0x1(%r8),%edx
  mov    %dl,0x1(%rcx)
  cmp    $0x1,%edi
  je     L294
  movzbl 0x2(%r8),%edx
  mov    %dl,0x2(%rcx)
  cmp    $0x2,%edi
  je     L294
  movzbl 0x3(%r8),%edx
  mov    %dl,0x3(%rcx)
  cmp    $0x3,%edi
  je     L294
  movzbl 0x4(%r8),%edx
  mov    %dl,0x4(%rcx)
  cmp    $0x4,%edi
  je     L294
  movzbl 0x5(%r8),%edx
  mov    %dl,0x5(%rcx)
  cmp    $0x5,%edi
  je     L294
  movzbl 0x6(%r8),%edx
  mov    %dl,0x6(%rcx)
L294:
  mov    %r10d,%r10d
  pop    %rbx
  lea    0x1(%rax,%r10,1),%rax
  ret
  nopw   0x0(%rax,%rax,1)
L141:
  movslq %edx,%rcx
  add    %rsi,%rcx
  cmp    %rcx,%rax
  jae    L129
  cmp    %rsi,%rax
  jbe    L297
  sub    $0x1,%edx
  js     L297
  movslq %edx,%rdx
L7:
  movzbl (%rsi,%rdx,1),%ecx
  mov    %cl,(%rax,%rdx,1)
  sub    $0x1,%rdx
  test   %edx,%edx
  jns    L7
  ret
L124:
  test   $0x3,%dl
  jne    L157
  cmp    %rsi,%rdi
  jb     L204
  movslq %edx,%rdi
  add    %rsi,%rdi
  cmp    %rdi,%rax
  jae    L204
  cmp    %rsi,%rax
  jbe    L297
  sub    $0x4,%edx
  js     L297
  movslq %edx,%rdx
  cs nopw 0x0(%rax,%rax,1)
L165:
  mov    (%rsi,%rdx,1),%rcx
  mov    %rcx,(%rax,%rdx,1)
  sub    $0x4,%rdx
  test   %edx,%edx
  jns    L165
  ret
  nopl   0x0(%rax)
L152:
  mov    %edi,%edx
  xor    %ecx,%ecx
  nopl   0x0(%rax)
L24:
  movzbl (%rsi,%rcx,1),%edi
  mov    %dil,(%rax,%rcx,1)
  mov    %rcx,%rdi
  add    $0x1,%rcx
  cmp    %rdx,%rdi
  jne    L24
  mov    %r10d,%r10d
  lea    0x1(%rax,%r10,1),%rax
L297:
  ret
  nopl   (%rax)
L204:
  cmp    $0x3,%edx
  jle    L297
  lea    -0x4(%rdx),%edi
  shr    $0x2,%edi
  lea    0x1(%rdi),%edi
  shl    $0x2,%rdi
  nopw   0x0(%rax,%rax,1)
L18:
  mov    (%rsi,%rcx,1),%rdx
  mov    %rdx,(%rax,%rcx,1)
  add    $0x4,%rcx
  cmp    %rdi,%rcx
  jne    L18
  add    %rcx,%rax
  ret
L179:
  mov    %rsi,%r8
  mov    %rax,%rcx
  xor    %r11d,%r11d
  jmp    L194
```

assistant: ```c
void *btff_memmove(register void *dest, register void *src, register int n) {
  if ((0x03 & (unsigned long)dest) || (0x03 & (unsigned long)src) || (0x03 & n)) {
    if (dest < src || src + n <= dest)
      for (n--; n >= 0; n--, dest++, src++)
        (*(unsigned char *)dest) = (*(unsigned char *)src);
    else if (src < dest)
      for (n--; n >= 0; n--)
        (*(unsigned char *)(dest + n)) = (*(unsigned char *)(src + n));
  } else {
    if (dest < src || src + n <= dest)
      for (n -= 4; n >= 0; n -= 4, dest += 4, src += 4)
        (*(unsigned long *)dest) = (*(unsigned long *)src);
    else if (src < dest)
      for (n -= 4; n >= 0; n -= 4)
        (*(unsigned long *)(dest + n)) = (*(unsigned long *)(src + n));
  }
  return dest;
}
```