user: 提供的汇编代码用C语言表示会是什么样子：

```asm
<byte_isequal>:
  endbr64
  test   %rsi,%rsi
  jle    L1
  mov    %rdi,%rcx
  mov    %rdx,%r10
  mov    %rsi,%r9
  cmp    $0xf,%rsi
  jle    L121
  mov    %rsi,%rdx
  xor    %eax,%eax
  pxor   %xmm0,%xmm0
  and    $0xfffffffffffffff0,%rdx
  nopl   (%rax)
L43:
  movdqu (%rcx,%rax,1),%xmm1
  movdqu (%r10,%rax,1),%xmm2
  add    $0x10,%rax
  pxor   %xmm2,%xmm1
  por    %xmm1,%xmm0
  cmp    %rdx,%rax
  jne    L43
  movdqa %xmm0,%xmm1
  mov    %rsi,%r11
  psrldq $0x8,%xmm1
  and    $0xfffffffffffffff0,%r11
  por    %xmm1,%xmm0
  lea    (%rcx,%r11,1),%r8
  lea    (%r10,%r11,1),%rdi
  sub    %r11,%rsi
  movdqa %xmm0,%xmm1
  psrldq $0x4,%xmm1
  por    %xmm1,%xmm0
  movdqa %xmm0,%xmm1
  psrldq $0x2,%xmm1
  por    %xmm1,%xmm0
  movdqa %xmm0,%xmm1
  psrldq $0x1,%xmm1
  por    %xmm1,%xmm0
  movd   %xmm0,%eax
  cmp    %r11,%r9
  je     L160
L178:
  sub    %r11,%r9
  lea    -0x1(%r9),%rdx
  cmp    $0x6,%rdx
  jbe    L42
  push   %rbx
  movq   (%rcx,%r11,1),%xmm1
  movq   (%r10,%r11,1),%xmm0
  pxor   %xmm0,%xmm1
  movq   %xmm1,%rcx
  movzbl %ch,%ebx
  mov    %ecx,%edx
  or     %ebx,%edx
  movq   %xmm1,%rbx
  or     %edx,%eax
  movq   %xmm1,%rdx
  shr    $0x38,%rbx
  shr    $0x10,%rdx
  or     %edx,%eax
  movq   %xmm1,%rdx
  shr    $0x18,%rdx
  or     %edx,%eax
  movq   %xmm1,%rdx
  shr    $0x20,%rdx
  or     %edx,%eax
  movq   %xmm1,%rdx
  shr    $0x28,%rdx
  or     %edx,%eax
  movq   %xmm1,%rdx
  shr    $0x30,%rdx
  or     %edx,%eax
  mov    %r9,%rdx
  and    $0xfffffffffffffff8,%rdx
  or     %ebx,%eax
  sub    %rdx,%rsi
  add    %rdx,%r8
  add    %rdx,%rdi
  cmp    %rdx,%r9
  je     L7
  movzbl (%r8),%edx
  xor    (%rdi),%dl
  or     %edx,%eax
  cmp    $0x1,%rsi
  je     L7
  movzbl 0x1(%rdi),%edx
  xor    0x1(%r8),%dl
  or     %edx,%eax
  cmp    $0x2,%rsi
  je     L7
  movzbl 0x2(%r8),%edx
  xor    0x2(%rdi),%dl
  or     %edx,%eax
  cmp    $0x3,%rsi
  je     L7
  movzbl 0x3(%r8),%edx
  xor    0x3(%rdi),%dl
  or     %edx,%eax
  cmp    $0x4,%rsi
  je     L7
  movzbl 0x4(%r8),%edx
  xor    0x4(%rdi),%dl
  or     %edx,%eax
  cmp    $0x5,%rsi
  je     L7
  movzbl 0x5(%r8),%edx
  xor    0x5(%rdi),%dl
  or     %edx,%eax
  cmp    $0x6,%rsi
  je     L7
  movzbl 0x6(%r8),%edx
  xor    0x6(%rdi),%dl
  or     %edx,%eax
L7:
  movzbl %al,%edx
  mov    $0x100,%eax
  pop    %rbx
  sub    %edx,%eax
  shr    $0x8,%eax
  ret
  nopl   (%rax)
L1:
  mov    $0x1,%eax
  ret
L42:
  movzbl (%r8),%edx
  xor    (%rdi),%dl
  or     %edx,%eax
  cmp    $0x1,%rsi
  je     L160
  movzbl 0x1(%rdi),%edx
  xor    0x1(%r8),%dl
  or     %edx,%eax
  cmp    $0x2,%rsi
  je     L160
  movzbl 0x2(%r8),%edx
  xor    0x2(%rdi),%dl
  or     %edx,%eax
  cmp    $0x3,%rsi
  je     L160
  movzbl 0x3(%r8),%edx
  xor    0x3(%rdi),%dl
  or     %edx,%eax
  cmp    $0x4,%rsi
  je     L160
  movzbl 0x4(%r8),%edx
  xor    0x4(%rdi),%dl
  or     %edx,%eax
  cmp    $0x5,%rsi
  je     L160
  movzbl 0x5(%r8),%edx
  xor    0x5(%rdi),%dl
  or     %edx,%eax
  cmp    $0x6,%rsi
  je     L160
  movzbl 0x6(%r8),%edx
  xor    0x6(%rdi),%dl
  or     %edx,%eax
L160:
  movzbl %al,%edx
  mov    $0x100,%eax
  sub    %edx,%eax
  shr    $0x8,%eax
  ret
L121:
  mov    %rdx,%rdi
  mov    %rcx,%r8
  xor    %r11d,%r11d
  xor    %eax,%eax
  jmp    L178
```

assistant: ```c
int byte_isequal(const void *yv, long long ylen, const void *xv) {
  const unsigned char *y = yv;
  const unsigned char *x = xv;
  unsigned char diff = 0;
  while (ylen > 0) {
    diff |= (*y++ ^ *x++);
    --ylen;
  }
  return (256 - (unsigned int)diff) >> 8;
}
```