user: 请从给定的汇编指令推导出C源代码:

```asm
<dist2>:
  endbr64
  mov    %ecx,%r10d
  or     %r8d,%r10d
  jne    L136
  test   %r9d,%r9d
  jle    L39
  movslq %edx,%r8
  xor    %r11d,%r11d
  nopw   0x0(%rax,%rax,1)
L173:
  xor    %edx,%edx
  nopw   0x0(%rax,%rax,1)
L20:
  movzbl (%rdi,%rdx,1),%eax
  movzbl (%rsi,%rdx,1),%ecx
  add    $0x1,%rdx
  sub    %ecx,%eax
  imul   %eax,%eax
  add    %eax,%r10d
  cmp    $0x10,%rdx
  jne    L20
  add    $0x1,%r11d
  add    %r8,%rdi
  add    %r8,%rsi
  cmp    %r11d,%r9d
  jne    L173
L39:
  mov    %r10d,%eax
  ret
L136:
  mov    %ecx,%eax
  test   %ecx,%ecx
  je     L86
  test   %r8d,%r8d
  jne    L86
  test   %r9d,%r9d
  jle    L151
  movslq %edx,%r8
  xor    %r10d,%r10d
  xor    %r11d,%r11d
  nopw   0x0(%rax,%rax,1)
L160:
  xor    %edx,%edx
  nopw   0x0(%rax,%rax,1)
L91:
  movzbl (%rdi,%rdx,1),%ecx
  movzbl 0x1(%rdi,%rdx,1),%eax
  lea    0x1(%rcx,%rax,1),%eax
  movzbl (%rsi,%rdx,1),%ecx
  add    $0x1,%rdx
  shr    %eax
  sub    %ecx,%eax
  imul   %eax,%eax
  add    %eax,%r10d
  cmp    $0x10,%rdx
  jne    L91
  add    $0x1,%r11d
  add    %r8,%rdi
  add    %r8,%rsi
  cmp    %r11d,%r9d
  jne    L160
  mov    %r10d,%eax
  ret
L86:
  movslq %edx,%rcx
  push   %rbx
  xor    %r10d,%r10d
  lea    (%rdi,%rcx,1),%r11
  test   %eax,%eax
  jne    L164
  test   %r8d,%r8d
  je     L164
  test   %r9d,%r9d
  jle    L67
  xor    %ebx,%ebx
  nopl   0x0(%rax,%rax,1)
L54:
  xor    %edx,%edx
  nopw   0x0(%rax,%rax,1)
L29:
  movzbl (%rdi,%rdx,1),%r8d
  movzbl (%r11,%rdx,1),%eax
  lea    0x1(%r8,%rax,1),%eax
  movzbl (%rsi,%rdx,1),%r8d
  add    $0x1,%rdx
  shr    %eax
  sub    %r8d,%eax
  imul   %eax,%eax
  add    %eax,%r10d
  cmp    $0x10,%rdx
  jne    L29
  add    $0x1,%ebx
  add    %rcx,%r11
  add    %rcx,%rsi
  add    %rcx,%rdi
  cmp    %ebx,%r9d
  jne    L54
L67:
  mov    %r10d,%eax
  pop    %rbx
  ret
L164:
  test   %r9d,%r9d
  jle    L67
  xor    %r8d,%r8d
  nopw   0x0(%rax,%rax,1)
L170:
  xor    %edx,%edx
  nopw   0x0(%rax,%rax,1)
L5:
  movzbl 0x1(%rdi,%rdx,1),%ebx
  movzbl (%rdi,%rdx,1),%eax
  add    %ebx,%eax
  movzbl (%r11,%rdx,1),%ebx
  add    %ebx,%eax
  movzbl 0x1(%r11,%rdx,1),%ebx
  lea    0x2(%rax,%rbx,1),%eax
  movzbl (%rsi,%rdx,1),%ebx
  add    $0x1,%rdx
  shr    $0x2,%eax
  sub    %ebx,%eax
  imul   %eax,%eax
  add    %eax,%r10d
  cmp    $0x10,%rdx
  jne    L5
  add    $0x1,%r8d
  add    %rcx,%r11
  add    %rcx,%rsi
  add    %rcx,%rdi
  cmp    %r8d,%r9d
  jne    L170
  mov    %r10d,%eax
  pop    %rbx
  ret
L151:
  xor    %r10d,%r10d
  jmp    L39
```

assistant: ```c
int dist2(blk1, blk2, lx, hx, hy, h)
unsigned char *blk1, *blk2;
int lx, hx, hy, h;
{
  unsigned char *p1, *p1a, *p2;
  int i, j;
  int s, v;
  s = 0;
  p1 = blk1;
  p2 = blk2;
  if (!hx && !hy)
    for (j = 0; j < h; j++) {
      for (i = 0; i < 16; i++) {
        v = p1[i] - p2[i];
        s += v * v;
      }
      p1 += lx;
      p2 += lx;
    }
  else if (hx && !hy)
    for (j = 0; j < h; j++) {
      for (i = 0; i < 16; i++) {
        v = ((unsigned int)(p1[i] + p1[i + 1] + 1) >> 1) - p2[i];
        s += v * v;
      }
      p1 += lx;
      p2 += lx;
    }
  else if (!hx && hy) {
    p1a = p1 + lx;
    for (j = 0; j < h; j++) {
      for (i = 0; i < 16; i++) {
        v = ((unsigned int)(p1[i] + p1a[i] + 1) >> 1) - p2[i];
        s += v * v;
      }
      p1 = p1a;
      p1a += lx;
      p2 += lx;
    }
  } else {
    p1a = p1 + lx;
    for (j = 0; j < h; j++) {
      for (i = 0; i < 16; i++) {
        v = ((unsigned int)(p1[i] + p1[i + 1] + p1a[i] + p1a[i + 1] + 2) >> 2) - p2[i];
        s += v * v;
      }
      p1 = p1a;
      p1a += lx;
      p2 += lx;
    }
  }
  return s;
}
```