user: 提供的汇编代码用C语言表示会是什么样子：

```asm
<SDL_imageFilterBitOr>:
  endbr64
  push   %r13
  xor    %eax,%eax
  mov    %ecx,%r13d
  push   %r12
  mov    %rsi,%r12
  push   %rbp
  mov    %rdi,%rbp
  push   %rbx
  mov    %rdx,%rbx
  sub    $0x8,%rsp
  call   <SDL_imageFilterMMXdetect@plt>
  test   %rax,%rax
  je     L36
  cmp    $0x7,%r13d
  jg     L176
L36:
  xor    %edx,%edx
L88:
  cmp    %edx,%r13d
  jbe    L3
  lea    0x1(%rbp),%rdi
  mov    %rbx,%rsi
  lea    0x1(%r12),%r8
  mov    %r13d,%ecx
  sub    %rdi,%rsi
  sub    %edx,%ecx
  cmp    $0xe,%rsi
  mov    %rbx,%rsi
  lea    -0x1(%rcx),%eax
  seta   %dil
  sub    %r8,%rsi
  cmp    $0xe,%rsi
  seta   %sil
  test   %sil,%dil
  je     L169
  cmp    $0x6,%eax
  jbe    L169
  cmp    $0xe,%eax
  jbe    L90
  mov    %ecx,%esi
  xor    %eax,%eax
  shr    $0x4,%esi
  shl    $0x4,%rsi
  xchg   %ax,%ax
L45:
  movdqu 0x0(%rbp,%rax,1),%xmm0
  movdqu (%r12,%rax,1),%xmm2
  por    %xmm2,%xmm0
  movups %xmm0,(%rbx,%rax,1)
  add    $0x10,%rax
  cmp    %rsi,%rax
  jne    L45
  mov    %ecx,%r9d
  and    $0xfffffff0,%r9d
  mov    %r9d,%eax
  add    %r9d,%edx
  lea    0x0(%rbp,%rax,1),%r8
  lea    (%r12,%rax,1),%rdi
  lea    (%rbx,%rax,1),%rsi
  cmp    %r9d,%ecx
  je     L3
  sub    %r9d,%ecx
  lea    -0x1(%rcx),%r9d
  cmp    $0x6,%r9d
  jbe    L33
L131:
  movq   0x0(%rbp,%rax,1),%xmm0
  movq   (%r12,%rax,1),%xmm1
  por    %xmm1,%xmm0
  movq   %xmm0,(%rbx,%rax,1)
  mov    %ecx,%eax
  and    $0xfffffff8,%eax
  mov    %eax,%r9d
  add    %eax,%edx
  add    %r9,%r8
  add    %r9,%rdi
  add    %r9,%rsi
  cmp    %eax,%ecx
  je     L3
L33:
  movzbl (%r8),%eax
  or     (%rdi),%al
  mov    %al,(%rsi)
  lea    0x1(%rdx),%eax
  cmp    %eax,%r13d
  jbe    L3
  movzbl 0x1(%r8),%eax
  or     0x1(%rdi),%al
  mov    %al,0x1(%rsi)
  lea    0x2(%rdx),%eax
  cmp    %eax,%r13d
  jbe    L3
  movzbl 0x2(%r8),%eax
  or     0x2(%rdi),%al
  mov    %al,0x2(%rsi)
  lea    0x3(%rdx),%eax
  cmp    %eax,%r13d
  jbe    L3
  movzbl 0x3(%r8),%eax
  or     0x3(%rdi),%al
  mov    %al,0x3(%rsi)
  lea    0x4(%rdx),%eax
  cmp    %eax,%r13d
  jbe    L3
  movzbl 0x4(%r8),%eax
  or     0x4(%rdi),%al
  mov    %al,0x4(%rsi)
  lea    0x5(%rdx),%eax
  cmp    %eax,%r13d
  jbe    L3
  movzbl 0x5(%r8),%eax
  add    $0x6,%edx
  or     0x5(%rdi),%al
  mov    %al,0x5(%rsi)
  cmp    %edx,%r13d
  jbe    L3
  movzbl 0x6(%r8),%eax
  or     0x6(%rdi),%al
  mov    %al,0x6(%rsi)
L3:
  add    $0x8,%rsp
  xor    %eax,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
L176:
  mov    %r13d,%ecx
  mov    %rbx,%rdx
  mov    %r12,%rsi
  mov    %rbp,%rdi
  call   <SDL_imageFilterBitOrMMX@plt>
  test   $0x7,%r13b
  je     L3
  mov    %r13d,%edx
  and    $0xfffffff8,%edx
  mov    %edx,%eax
  add    %rax,%rbp
  add    %rax,%r12
  add    %rax,%rbx
  jmp    L88
  nopl   (%rax)
L169:
  sub    $0x1,%r13d
  xor    %eax,%eax
  sub    %edx,%r13d
  nopl   0x0(%rax)
L97:
  movzbl 0x0(%rbp,%rax,1),%edx
  or     (%r12,%rax,1),%dl
  mov    %dl,(%rbx,%rax,1)
  mov    %rax,%rdx
  add    $0x1,%rax
  cmp    %r13,%rdx
  jne    L97
  add    $0x8,%rsp
  xor    %eax,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
L90:
  mov    %rbx,%rsi
  mov    %r12,%rdi
  mov    %rbp,%r8
  xor    %eax,%eax
  jmp    L131
```

assistant: ```c
int SDL_imageFilterBitOr(unsigned char *Src1, unsigned char *Src2, unsigned char *Dest, int length) {
  unsigned int i, istart;
  unsigned char *cursrc1, *cursrc2, *curdst;
  if ((SDL_imageFilterMMXdetect()) && (length > 7)) {
    SDL_imageFilterBitOrMMX(Src1, Src2, Dest, length);
    if ((length & 7) > 0) {
      istart = length & 0xfffffff8;
      cursrc1 = &Src1[istart];
      cursrc2 = &Src2[istart];
      curdst = &Dest[istart];
    } else {
      return (0);
    }
  } else {
    istart = 0;
    cursrc1 = Src1;
    cursrc2 = Src2;
    curdst = Dest;
  }
  for (i = istart; i < length; i++) {
    *curdst = *cursrc1 | *cursrc2;
    cursrc1++;
    cursrc2++;
    curdst++;
  }
  return (0);
}
```