user: 这段汇编代码用C语言表示是什么样的:

```asm
<png_find_best_filter>:
  endbr64
  push   %r15
  mov    %ecx,%r15d
  push   %r14
  push   %r13
  mov    %esi,%r13d
  push   %r12
  mov    %rdi,%r12
  push   %rbp
  push   %rbx
  mov    %edx,%ebx
  sar    $0x3,%ebx
  imul   %ebx,%r13d
  sub    $0xa8,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0x98(%rsp)
  xor    %eax,%eax
  call   <make_num_bits_table@plt>
  test   %r15d,%r15d
  jle    L89
  movl   $0x5,0x1c(%rsp)
  mov    %r13d,%r15d
L1:
  mov    $0x2000,%esi
  mov    $0x1,%edi
  call   <calloc@plt>
  mov    $0x2000,%esi
  mov    $0x1,%edi
  mov    %rax,(%rsp)
  call   <calloc@plt>
  mov    $0x2000,%esi
  mov    $0x1,%edi
  mov    %rax,0x20(%rsp)
  mov    %rax,0x68(%rsp)
  call   <calloc@plt>
  mov    $0x2000,%esi
  mov    $0x1,%edi
  mov    %rax,0x28(%rsp)
  mov    %rax,0x70(%rsp)
  call   <calloc@plt>
  mov    $0x2000,%esi
  mov    $0x1,%edi
  mov    %rax,0x30(%rsp)
  mov    %rax,0x78(%rsp)
  call   <calloc@plt>
  xor    %edi,%edi
  mov    %rax,0x38(%rsp)
  mov    %rax,0x80(%rsp)
  lea    -0x1(%rbx),%eax
  movslq %eax,%rdx
  sub    %r15d,%eax
  movzbl (%r12,%rdx,1),%ebp
  cltq
  xor    %edx,%edx
  movzbl (%r12,%rax,1),%esi
  mov    %ebp,%eax
  mov    %bpl,0x8e(%rsp)
  sub    %esi,%eax
  mov    %bpl,0x8f(%rsp)
  mov    %al,0x90(%rsp)
  mov    %al,0x91(%rsp)
  call   <PaethPredictor@plt>
  mov    %ebp,%ecx
  movl   $0x0,0x50(%rsp)
  movq   $0x0,0x40(%rsp)
  sub    %eax,%ecx
  mov    %cl,0x92(%rsp)
  movq   $0x0,0x48(%rsp)
  cmp    %r13d,%ebx
  jge    L108
  mov    %r15d,%eax
  sub    %ebx,%r13d
  movslq %r15d,%r15
  movslq %ebx,%rbx
  neg    %eax
  lea    -0x1(%r13),%edx
  lea    0x8e(%rsp),%r14
  cltq
  mov    %r14,%r13
  lea    (%r12,%rax,1),%rbp
  lea    0x1(%r12,%rdx,1),%r12
  add    %r12,%rax
  lea    0x93(%rsp),%r12
  mov    %rbp,%r14
  mov    %rax,0x8(%rsp)
  lea    (%rbx,%r15,1),%rax
  mov    %rax,0x10(%rsp)
  mov    %rbx,%rax
  mov    %r12,%rbx
  mov    %rax,%r12
  nopl   0x0(%rax,%rax,1)
L72:
  lea    (%r15,%r14,1),%rax
  movzbl (%r14,%r15,1),%edi
  movzbl (%rax,%r12,1),%ebp
  mov    %ebp,%eax
  mov    %bpl,0x93(%rsp)
  sub    %edi,%eax
  mov    %al,0x94(%rsp)
  mov    0x10(%rsp),%rax
  lea    (%rax,%r14,1),%rdx
  mov    %r15,%rax
  neg    %rax
  movzbl (%rdx,%rax,1),%esi
  mov    %ebp,%eax
  mov    %ebp,%edx
  sub    %esi,%eax
  mov    %al,0x95(%rsp)
  lea    (%rdi,%rsi,1),%eax
  sar    %eax
  sub    %eax,%edx
  mov    %dl,0x96(%rsp)
  movzbl (%r14),%edx
  call   <PaethPredictor@plt>
  mov    %ebp,%ecx
  mov    (%rsp),%rsi
  xor    %edi,%edi
  sub    %eax,%ecx
  mov    $0x1,%r10d
  mov    %cl,0x97(%rsp)
L59:
  movzbl (%rbx,%rdi,1),%eax
  movzbl 0x0(%r13,%rdi,1),%ecx
  mov    %r10d,%edx
  shl    $0x8,%eax
  or     %ecx,%eax
  and    $0x7,%ecx
  sar    $0x3,%eax
  shl    %cl,%edx
  cltq
  add    %rax,%rsi
  xor    %eax,%eax
  cmpb   $0x0,(%rsi)
  sete   %al
  test   %edx,%eax
  je     L38
  addl   $0x1,0x40(%rsp,%rdi,4)
  mov    %dl,(%rsi)
L38:
  add    $0x1,%rdi
  cmp    $0x5,%rdi
  je     L100
  mov    0x60(%rsp,%rdi,8),%rsi
  jmp    L59
  nopw   0x0(%rax,%rax,1)
L100:
  mov    $0x5,%edx
  mov    %rbx,%rsi
  mov    %r13,%rdi
  add    $0x1,%r14
  call   <memcpy@plt>
  cmp    %r14,0x8(%rsp)
  jne    L72
  mov    0x40(%rsp),%edx
L43:
  mov    D2(%rip),%rax
  mov    0x1c(%rsp),%esi
  xor    %r12d,%r12d
  mov    (%rax),%ecx
  xor    %eax,%eax
  cmp    %edx,%ecx
  jle    L8
L103:
  mov    %edx,%ecx
  mov    %eax,%r12d
L8:
  add    $0x1,%rax
  cmp    %eax,%esi
  jle    L126
L125:
  mov    0x40(%rsp,%rax,4),%edx
  cmp    %edx,%ecx
  jg     L103
  add    $0x1,%rax
  cmp    %eax,%esi
  jg     L125
L126:
  mov    (%rsp),%rdi
  call   <free@plt>
  mov    0x20(%rsp),%rdi
  call   <free@plt>
  mov    0x28(%rsp),%rdi
  call   <free@plt>
  mov    0x30(%rsp),%rdi
  call   <free@plt>
  mov    0x38(%rsp),%rdi
  call   <free@plt>
  mov    0x98(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L52
  add    $0xa8,%rsp
  mov    %r12d,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L89:
  movl   $0x2,0x1c(%rsp)
  cmovne %r13d,%r15d
  jmp    L1
L108:
  xor    %edx,%edx
  jmp    L43
L52:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int png_find_best_filter(unsigned char *src, unsigned width, int bpp, int y) {
  make_num_bits_table();
  int num_filters = y > 0 ? 5 : 2;
  int bytes_per_pixel = bpp >> 3;
  int w = width * bytes_per_pixel;
  int back_x = bytes_per_pixel;
  int back_y = y ? width * bytes_per_pixel : 0;
  unsigned char *pairs[5];
  pairs[0] = calloc(1, 8192);
  pairs[1] = calloc(1, 8192);
  pairs[2] = calloc(1, 8192);
  pairs[3] = calloc(1, 8192);
  pairs[4] = calloc(1, 8192);
  unsigned char old[5];
  int l = bytes_per_pixel - 1;
  old[0] = src[l];
  old[1] = src[l];
  old[2] = src[l] - src[l - back_y];
  old[3] = src[l] - src[l - back_y];
  old[4] = src[l] - PaethPredictor(0, src[l - back_y], 0);
  int different_pairs[5] = {0, 0, 0, 0, 0};
  int x;
  for (x = bytes_per_pixel; x < w; x++) {
    unsigned char dest[5];
    dest[0] = src[x];
    dest[1] = src[x] - src[x - back_x];
    dest[2] = src[x] - src[x - back_y];
    dest[3] = src[x] - (src[x - back_x] + src[x - back_y]) / 2;
    dest[4] = src[x] - PaethPredictor(src[x - back_x], src[x - back_y], src[x - back_x - back_y]);
    int i;
    for (i = 0; i < 5; i++) {
      int v = dest[i] << 8 | old[i];
      int p = v >> 3;
      int b = 1 << (v & 7);
      if (!pairs[i][p] & b) {
        pairs[i][p] |= b;
        different_pairs[i]++;
      }
    }
    memcpy(old, dest, sizeof(old));
  }
  int f;
  int best_nr = 0;
  int best_energy = INT_MAX;
  for (f = 0; f < num_filters; f++) {
    int energy = different_pairs[f];
    if (energy < best_energy) {
      best_nr = f;
      best_energy = energy;
    }
  }
  free(pairs[0]);
  free(pairs[1]);
  free(pairs[2]);
  free(pairs[3]);
  free(pairs[4]);
  return best_nr;
}
```