user: 请将以下的汇编代码转换成C语言代码:

```asm
<vpx_post_proc_down_and_across_mb_row_c>:
  endbr64
  push   %r15
  mov    %edx,%eax
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x88,%rsp
  mov    %r8d,0x3c(%rsp)
  mov    %r9,0x40(%rsp)
  mov    %fs:0x28,%rdx
  mov    %rdx,0x78(%rsp)
  xor    %edx,%edx
  mov    0xc0(%rsp),%edx
  test   %edx,%edx
  jle    L18
  movslq %eax,%r10
  movslq %r8d,%rdx
  movslq %ecx,%rcx
  mov    %rsi,%rbx
  lea    (%rax,%rax,1),%esi
  neg    %eax
  mov    %rcx,0x50(%rsp)
  mov    %rdx,%rcx
  mov    %rdx,0x10(%rsp)
  cltq
  sub    $0x1,%rdx
  add    %rdi,%rax
  mov    %rdx,0x60(%rsp)
  mov    %esi,%edx
  mov    %rax,0x28(%rsp)
  neg    %edx
  lea    (%rdi,%r10,1),%rax
  mov    %rax,0x20(%rsp)
  movslq %edx,%rdx
  movslq %esi,%rax
  add    %rdi,%rdx
  mov    %rax,0x58(%rsp)
  add    %rax,%rdi
  lea    -0x2(%rcx),%eax
  mov    %r10,0x48(%rsp)
  mov    %rdx,0x8(%rsp)
  mov    %rdi,0x18(%rsp)
  movl   $0x0,0x68(%rsp)
  mov    %eax,0x6c(%rsp)
  nopl   (%rax)
L214:
  mov    0x58(%rsp),%rax
  add    0x8(%rsp),%rax
  xor    %r15d,%r15d
  mov    %rax,0x30(%rsp)
  mov    0x3c(%rsp),%eax
  mov    0x40(%rsp),%r12
  test   %eax,%eax
  jg     L67
  jmp    L144
  nopl   0x0(%rax)
L71:
  mov    %r14b,(%rbx,%r15,1)
  add    $0x1,%r15
  cmp    %r15,0x10(%rsp)
  je     L113
L67:
  mov    0x8(%rsp),%rax
  movzbl (%rax,%r15,1),%ebp
  mov    0x28(%rsp),%rax
  movzbl (%rax,%r15,1),%r13d
  mov    0x20(%rsp),%rax
  movzbl (%rax,%r15,1),%eax
  mov    %al,0x3a(%rsp)
  mov    0x18(%rsp),%rax
  movzbl (%rax,%r15,1),%eax
  mov    %al,0x3b(%rsp)
  mov    0x30(%rsp),%rax
  movzbl (%rax,%r15,1),%r14d
  mov    %r14d,%edi
  sub    %ebp,%edi
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    (%r12,%r15,1),%al
  jae    L71
  mov    %r14d,%edi
  sub    %r13d,%edi
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    (%r12,%r15,1),%al
  jae    L71
  mov    %r14d,%edi
  sub    0x3a(%rsp),%dil
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    (%r12,%r15,1),%al
  jae    L71
  mov    %r14d,%edi
  sub    0x3b(%rsp),%dil
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    (%r12,%r15,1),%al
  jae    L71
  movzbl 0x3b(%rsp),%edx
  movzbl 0x3a(%rsp),%eax
  lea    0x1(%rbp,%r13,1),%esi
  movzbl %r14b,%ecx
  sar    %esi
  lea    0x1(%rdx,%rax,1),%eax
  sar    %eax
  lea    0x1(%rsi,%rax,1),%eax
  sar    %eax
  lea    0x1(%rax,%rcx,1),%ecx
  sar    %ecx
  mov    %ecx,%r14d
  mov    %r14b,(%rbx,%r15,1)
  add    $0x1,%r15
  cmp    %r15,0x10(%rsp)
  jne    L67
  nopl   0x0(%rax)
L113:
  movzbl (%rbx),%eax
  mov    0x10(%rsp),%rcx
  mov    %rbx,%r15
  mov    0x40(%rsp),%r12
  mov    %al,-0x1(%rbx)
  mov    %al,-0x2(%rbx)
  movzbl -0x1(%rbx,%rcx,1),%eax
  mov    %r12,%r14
  mov    %al,0x1(%rbx,%rcx,1)
  mov    %al,(%rbx,%rcx,1)
  mov    0x3c(%rsp),%eax
  lea    -0x1(%rax),%esi
  mov    $0x1,%eax
  test   %esi,%esi
  cmovle %esi,%eax
  xor    %ebp,%ebp
  mov    %eax,%r12d
  jmp    L186
  nopl   (%rax)
L245:
  movslq %ebp,%rax
  add    $0x1,%r15
  add    $0x1,%r14
  mov    %r13b,0x74(%rsp,%rax,1)
  lea    0x1(%rbp),%eax
  mov    $0x1,%ebp
  cmp    %eax,%r12d
  jl     L249
L186:
  movzbl (%r15),%r13d
  mov    %r13d,%edi
  sub    -0x2(%r15),%dil
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    (%r14),%al
  jae    L245
  mov    %r13d,%edi
  sub    -0x1(%r15),%dil
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    (%r14),%al
  jae    L245
  mov    %r13d,%edi
  sub    0x1(%r15),%dil
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    (%r14),%al
  jae    L245
  mov    %r13d,%edi
  sub    0x2(%r15),%dil
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    (%r14),%al
  jae    L245
  movzbl -0x1(%r15),%eax
  movzbl -0x2(%r15),%edx
  movzbl 0x2(%r15),%ecx
  lea    0x1(%rdx,%rax,1),%edx
  movzbl 0x1(%r15),%eax
  sar    %edx
  lea    0x1(%rcx,%rax,1),%eax
  sar    %eax
  lea    0x1(%rdx,%rax,1),%eax
  sar    %eax
  lea    0x1(%rax,%r13,1),%r13d
  sar    %r13d
  jmp    L245
  nopl   0x0(%rax)
L249:
  mov    %eax,%r14d
  cmp    %eax,0x3c(%rsp)
  jle    L197
  movslq %r14d,%r12
  mov    0x3c(%rsp),%r15d
  lea    (%rbx,%r12,1),%rbp
  add    0x40(%rsp),%r12
  jmp    L38
  nopl   0x0(%rax,%rax,1)
L246:
  mov    %r14d,%eax
  add    $0x1,%rbp
  add    $0x1,%r12
  and    $0x3,%eax
  mov    %r13b,0x74(%rsp,%rax,1)
  lea    -0x2(%r14),%eax
  add    $0x1,%r14d
  and    $0x3,%eax
  movzbl 0x74(%rsp,%rax,1),%eax
  mov    %al,-0x3(%rbp)
  cmp    %r14d,%r15d
  je     L197
L38:
  movzbl 0x0(%rbp),%r13d
  mov    %r13d,%edi
  sub    -0x2(%rbp),%dil
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    %al,(%r12)
  jbe    L246
  mov    %r13d,%edi
  sub    -0x1(%rbp),%dil
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    %al,(%r12)
  jbe    L246
  mov    %r13d,%edi
  sub    0x1(%rbp),%dil
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    %al,(%r12)
  jbe    L246
  mov    %r13d,%edi
  sub    0x2(%rbp),%dil
  movzbl %dil,%edi
  call   <abs@plt>
  cmp    %al,(%r12)
  jbe    L246
  movzbl 0x2(%rbp),%eax
  movzbl 0x1(%rbp),%edx
  movzbl -0x1(%rbp),%ecx
  lea    0x1(%rdx,%rax,1),%edx
  movzbl -0x2(%rbp),%eax
  sar    %edx
  lea    0x1(%rcx,%rax,1),%eax
  sar    %eax
  lea    0x1(%rdx,%rax,1),%eax
  sar    %eax
  lea    0x1(%rax,%r13,1),%r13d
  sar    %r13d
  jmp    L246
  nop
L197:
  mov    0x10(%rsp),%rcx
  mov    0x6c(%rsp),%eax
  lea    -0x2(%rcx),%rdx
  mov    0x60(%rsp),%rcx
  and    $0x3,%eax
L33:
  cltq
  addl   $0x1,0x68(%rsp)
  mov    0x68(%rsp),%esi
  movzbl 0x74(%rsp,%rax,1),%eax
  mov    %al,(%rbx,%rdx,1)
  mov    0x48(%rsp),%rax
  mov    %r13b,(%rbx,%rcx,1)
  add    0x50(%rsp),%rbx
  add    %rax,0x8(%rsp)
  add    %rax,0x28(%rsp)
  add    %rax,0x20(%rsp)
  add    %rax,0x18(%rsp)
  cmp    %esi,0xc0(%rsp)
  jne    L214
L18:
  mov    0x78(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L7
  add    $0x88,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax)
L144:
  movzbl (%rbx),%eax
  mov    0x10(%rsp),%rdx
  mov    $0xffffffffffffffff,%rcx
  movzbl 0x77(%rsp),%r13d
  mov    %al,-0x1(%rbx)
  mov    %al,-0x2(%rbx)
  movzbl -0x1(%rbx,%rdx,1),%eax
  mov    %al,0x1(%rbx,%rdx,1)
  mov    %al,(%rbx,%rdx,1)
  mov    $0xfffffffffffffffe,%rdx
  mov    $0x2,%eax
  jmp    L33
L7:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void vpx_post_proc_down_and_across_mb_row_c(unsigned char *src_ptr, unsigned char *dst_ptr, int src_pixels_per_line, int dst_pixels_per_line, int cols, unsigned char *f, int size) {
  unsigned char *p_src, *p_dst;
  int row;
  int col;
  unsigned char v;
  unsigned char d[4];
  for (row = 0; row < size; row++) {
    p_src = src_ptr;
    p_dst = dst_ptr;
    for (col = 0; col < cols; col++) {
      unsigned char p_above2 = p_src[col - 2 * src_pixels_per_line];
      unsigned char p_above1 = p_src[col - src_pixels_per_line];
      unsigned char p_below1 = p_src[col + src_pixels_per_line];
      unsigned char p_below2 = p_src[col + 2 * src_pixels_per_line];
      v = p_src[col];
      if ((abs(v - p_above2) < f[col]) && (abs(v - p_above1) < f[col]) && (abs(v - p_below1) < f[col]) && (abs(v - p_below2) < f[col])) {
        unsigned char k1, k2, k3;
        k1 = (p_above2 + p_above1 + 1) >> 1;
        k2 = (p_below2 + p_below1 + 1) >> 1;
        k3 = (k1 + k2 + 1) >> 1;
        v = (k3 + v + 1) >> 1;
      }
      p_dst[col] = v;
    }
    p_src = dst_ptr;
    p_dst = dst_ptr;
    p_src[-2] = p_src[-1] = p_src[0];
    p_src[cols] = p_src[cols + 1] = p_src[cols - 1];
    for (col = 0; col < cols; col++) {
      v = p_src[col];
      if ((abs(v - p_src[col - 2]) < f[col]) && (abs(v - p_src[col - 1]) < f[col]) && (abs(v - p_src[col + 1]) < f[col]) && (abs(v - p_src[col + 2]) < f[col])) {
        unsigned char k1, k2, k3;
        k1 = (p_src[col - 2] + p_src[col - 1] + 1) >> 1;
        k2 = (p_src[col + 2] + p_src[col + 1] + 1) >> 1;
        k3 = (k1 + k2 + 1) >> 1;
        v = (k3 + v + 1) >> 1;
      }
      d[col & 3] = v;
      if (col >= 2)
        p_dst[col - 2] = d[(col - 2) & 3];
    }
    p_dst[col - 2] = d[(col - 2) & 3];
    p_dst[col - 1] = d[(col - 1) & 3];
    src_ptr += src_pixels_per_line;
    dst_ptr += dst_pixels_per_line;
  }
}
```