user: 这段汇编代码用C语言表示是什么样的:

```asm
<rte_memcpy_func>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x8,%rsp
  mov    %rdi,%r15
  mov    %rsi,%rbp
  mov    %rdx,%rbx
  cmp    $0xf,%rdx
  jbe    L121
  cmp    $0x20,%rdx
  jbe    L81
  cmp    $0x40,%rdx
  jbe    L165
  cmp    $0x80,%rdx
  jbe    L109
  mov    %rdx,%r14
  mov    %rsi,%r13
  mov    %rdi,%r12
  cmp    $0xff,%rdx
  jbe    L67
L209:
  mov    %r13,%rsi
  mov    %r12,%rdi
  call   <rte_mov256@plt>
  add    $0x400,%r12
  add    $0x400,%r13
  sub    $0x100,%r14
  cmp    $0xff,%r14
  ja     L209
  lea    -0x100(%rbx),%rax
  shr    $0x8,%rax
  add    $0x1,%rax
  shl    $0xa,%rax
  lea    (%r15,%rax,1),%r12
  add    %rax,%rbp
  movzbl %bl,%ebx
  mov    %rbx,%rdx
  shr    $0x6,%rdx
  mov    $0x3,%eax
  sub    %rdx,%rax
  cmp    $0x1,%rax
  je     L223
  cmp    $0x2,%rax
  je     L83
  test   %rax,%rax
  jne    L128
L110:
  mov    %rbp,%rsi
  mov    %r12,%rdi
  call   <rte_mov64@plt>
  sub    $0x40,%rbx
  add    $0x100,%r12
  add    $0x100,%rbp
L223:
  mov    %rbp,%rsi
  mov    %r12,%rdi
  call   <rte_mov64@plt>
  sub    $0x40,%rbx
  add    $0x100,%r12
  add    $0x100,%rbp
L83:
  mov    %rbp,%rsi
  mov    %r12,%rdi
  call   <rte_mov64@plt>
  sub    $0x40,%rbx
  add    $0x100,%r12
  add    $0x100,%rbp
L128:
  mov    %rbx,%rdx
  shr    $0x4,%rdx
  mov    $0x3,%eax
  sub    %rdx,%rax
  cmp    $0x1,%rax
  je     L224
  cmp    $0x2,%rax
  je     L7
  test   %rax,%rax
  jne    L15
  mov    %rbp,%rsi
  mov    %r12,%rdi
  call   <rte_mov16@plt>
  sub    $0x10,%rbx
  add    $0x40,%r12
  add    $0x40,%rbp
L224:
  mov    %rbp,%rsi
  mov    %r12,%rdi
  call   <rte_mov16@plt>
  sub    $0x10,%rbx
  add    $0x40,%r12
  add    $0x40,%rbp
L7:
  mov    %rbp,%rsi
  mov    %r12,%rdi
  call   <rte_mov16@plt>
  sub    $0x10,%rbx
  add    $0x40,%r12
  add    $0x40,%rbp
L15:
  test   %rbx,%rbx
  jne    L129
L90:
  mov    %r15,%rax
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L121:
  mov    %rdi,%rax
  test   $0x1,%dl
  je     L142
  mov    (%rsi),%eax
  mov    %eax,(%rdi)
  lea    0x4(%rdi),%rax
  add    $0x4,%rbp
L142:
  test   $0x2,%bl
  je     L215
  mov    0x0(%rbp),%edx
  mov    %edx,(%rax)
  add    $0x4,%rax
  add    $0x4,%rbp
L215:
  test   $0x4,%bl
  je     L226
  mov    0x0(%rbp),%edx
  mov    %edx,(%rax)
  add    $0x4,%rax
  add    $0x4,%rbp
L226:
  test   $0x8,%bl
  je     L90
  mov    0x0(%rbp),%edx
  mov    %edx,(%rax)
  jmp    L90
L81:
  call   <rte_mov16@plt>
  lea    -0x40(,%rbx,4),%rdi
  lea    0x0(%rbp,%rdi,1),%rsi
  add    %r15,%rdi
  call   <rte_mov16@plt>
  jmp    L90
L165:
  call   <rte_mov32@plt>
  lea    -0x80(,%rbx,4),%rdi
  lea    0x0(%rbp,%rdi,1),%rsi
  add    %r15,%rdi
  call   <rte_mov32@plt>
  jmp    L90
L109:
  call   <rte_mov64@plt>
  lea    -0x100(,%rbx,4),%rdi
  lea    0x0(%rbp,%rdi,1),%rsi
  add    %r15,%rdi
  call   <rte_mov64@plt>
  jmp    L90
L129:
  lea    -0x40(,%rbx,4),%rdi
  lea    0x0(%rbp,%rdi,1),%rsi
  add    %r12,%rdi
  call   <rte_mov16@plt>
  jmp    L90
L67:
  mov    %rdx,%rax
  shr    $0x6,%rax
  cmp    $0x2,%rax
  jne    L110
  jmp    L223
```

assistant: ```c
void *rte_memcpy_func(void *dst, const void *src, size_t n) {
  void *ret = dst;
  if (n < 16) {
    if (n & 0x01) {
      *(uint8_t *)dst = *(const uint8_t *)src;
      dst = (uint8_t *)dst + 1;
      src = (const uint8_t *)src + 1;
    }
    if (n & 0x02) {
      *(uint16_t *)dst = *(const uint16_t *)src;
      dst = (uint16_t *)dst + 1;
      src = (const uint16_t *)src + 1;
    }
    if (n & 0x04) {
      *(uint32_t *)dst = *(const uint32_t *)src;
      dst = (uint32_t *)dst + 1;
      src = (const uint32_t *)src + 1;
    }
    if (n & 0x08) {
      *(uint64_t *)dst = *(const uint64_t *)src;
    }
    return ret;
  }
  if (n <= 32) {
    rte_mov16((uint8_t *)dst, (const uint8_t *)src);
    rte_mov16((uint8_t *)dst - 16 + n, (const uint8_t *)src - 16 + n);
    return ret;
  }
  if (n <= 64) {
    rte_mov32((uint8_t *)dst, (const uint8_t *)src);
    rte_mov32((uint8_t *)dst - 32 + n, (const uint8_t *)src - 32 + n);
    return ret;
  }
  if (n <= 128) {
    rte_mov64((uint8_t *)dst, (const uint8_t *)src);
    rte_mov64((uint8_t *)dst - 64 + n, (const uint8_t *)src - 64 + n);
    return ret;
  }
  for (; n >= 256; n -= 256) {
    rte_mov256((uint8_t *)dst, (const uint8_t *)src);
    dst = (uint8_t *)dst + 256;
    src = (const uint8_t *)src + 256;
  }
  switch (3 - (n >> 6)) {
  case 0x00:
    rte_mov64((uint8_t *)dst, (const uint8_t *)src);
    n -= 64;
    dst = (uint8_t *)dst + 64;
    src = (const uint8_t *)src + 64;
  case 0x01:
    rte_mov64((uint8_t *)dst, (const uint8_t *)src);
    n -= 64;
    dst = (uint8_t *)dst + 64;
    src = (const uint8_t *)src + 64;
  case 0x02:
    rte_mov64((uint8_t *)dst, (const uint8_t *)src);
    n -= 64;
    dst = (uint8_t *)dst + 64;
    src = (const uint8_t *)src + 64;
  default:;
  }
  switch (3 - (n >> 4)) {
  case 0x00:
    rte_mov16((uint8_t *)dst, (const uint8_t *)src);
    n -= 16;
    dst = (uint8_t *)dst + 16;
    src = (const uint8_t *)src + 16;
  case 0x01:
    rte_mov16((uint8_t *)dst, (const uint8_t *)src);
    n -= 16;
    dst = (uint8_t *)dst + 16;
    src = (const uint8_t *)src + 16;
  case 0x02:
    rte_mov16((uint8_t *)dst, (const uint8_t *)src);
    n -= 16;
    dst = (uint8_t *)dst + 16;
    src = (const uint8_t *)src + 16;
  default:;
  }
  if (n != 0) {
    rte_mov16((uint8_t *)dst - 16 + n, (const uint8_t *)src - 16 + n);
  }
  return ret;
}
```