user: What is the c source code of the assembly code below:

```asm
<vp8_short_walsh4x4_c>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x48(%rbp)
  mov    %rsi,-0x50(%rbp)
  mov    %edx,-0x54(%rbp)
  mov    -0x48(%rbp),%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x50(%rbp),%rax
  mov    %rax,-0x8(%rbp)
  movl   $0x0,-0x34(%rbp)
  jmp    L11
L13:
  mov    -0x10(%rbp),%rax
  movzwl (%rax),%eax
  movswl %ax,%edx
  mov    -0x10(%rbp),%rax
  add    $0x4,%rax
  movzwl (%rax),%eax
  cwtl
  add    %edx,%eax
  shl    $0x2,%eax
  mov    %eax,-0x30(%rbp)
  mov    -0x10(%rbp),%rax
  add    $0x2,%rax
  movzwl (%rax),%eax
  movswl %ax,%edx
  mov    -0x10(%rbp),%rax
  add    $0x6,%rax
  movzwl (%rax),%eax
  cwtl
  add    %edx,%eax
  shl    $0x2,%eax
  mov    %eax,-0x2c(%rbp)
  mov    -0x10(%rbp),%rax
  add    $0x2,%rax
  movzwl (%rax),%eax
  cwtl
  mov    -0x10(%rbp),%rdx
  add    $0x6,%rdx
  movzwl (%rdx),%edx
  movswl %dx,%edx
  sub    %edx,%eax
  shl    $0x2,%eax
  mov    %eax,-0x28(%rbp)
  mov    -0x10(%rbp),%rax
  movzwl (%rax),%eax
  cwtl
  mov    -0x10(%rbp),%rdx
  add    $0x4,%rdx
  movzwl (%rdx),%edx
  movswl %dx,%edx
  sub    %edx,%eax
  shl    $0x2,%eax
  mov    %eax,-0x24(%rbp)
  mov    -0x30(%rbp),%eax
  mov    %eax,%edx
  mov    -0x2c(%rbp),%eax
  add    %eax,%edx
  cmpl   $0x0,-0x30(%rbp)
  setne  %al
  movzbl %al,%eax
  add    %edx,%eax
  mov    %eax,%edx
  mov    -0x8(%rbp),%rax
  mov    %dx,(%rax)
  mov    -0x24(%rbp),%eax
  mov    %eax,%edx
  mov    -0x28(%rbp),%eax
  add    %eax,%edx
  mov    -0x8(%rbp),%rax
  add    $0x2,%rax
  mov    %dx,(%rax)
  mov    -0x24(%rbp),%eax
  mov    %eax,%edx
  mov    -0x28(%rbp),%eax
  sub    %eax,%edx
  mov    -0x8(%rbp),%rax
  add    $0x4,%rax
  mov    %dx,(%rax)
  mov    -0x30(%rbp),%eax
  mov    %eax,%edx
  mov    -0x2c(%rbp),%eax
  sub    %eax,%edx
  mov    -0x8(%rbp),%rax
  add    $0x6,%rax
  mov    %dx,(%rax)
  mov    -0x54(%rbp),%eax
  mov    %eax,%edx
  shr    $0x1f,%edx
  add    %edx,%eax
  sar    %eax
  cltq
  add    %rax,%rax
  add    %rax,-0x10(%rbp)
  addq   $0x8,-0x8(%rbp)
  addl   $0x1,-0x34(%rbp)
L11:
  cmpl   $0x3,-0x34(%rbp)
  jle    L13
  mov    -0x50(%rbp),%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x50(%rbp),%rax
  mov    %rax,-0x8(%rbp)
  movl   $0x0,-0x34(%rbp)
  jmp    L32
L30:
  mov    -0x10(%rbp),%rax
  movzwl (%rax),%eax
  movswl %ax,%edx
  mov    -0x10(%rbp),%rax
  add    $0x10,%rax
  movzwl (%rax),%eax
  cwtl
  add    %edx,%eax
  mov    %eax,-0x30(%rbp)
  mov    -0x10(%rbp),%rax
  add    $0x8,%rax
  movzwl (%rax),%eax
  movswl %ax,%edx
  mov    -0x10(%rbp),%rax
  add    $0x18,%rax
  movzwl (%rax),%eax
  cwtl
  add    %edx,%eax
  mov    %eax,-0x2c(%rbp)
  mov    -0x10(%rbp),%rax
  add    $0x8,%rax
  movzwl (%rax),%eax
  cwtl
  mov    -0x10(%rbp),%rdx
  add    $0x18,%rdx
  movzwl (%rdx),%edx
  movswl %dx,%edx
  sub    %edx,%eax
  mov    %eax,-0x28(%rbp)
  mov    -0x10(%rbp),%rax
  movzwl (%rax),%eax
  cwtl
  mov    -0x10(%rbp),%rdx
  add    $0x10,%rdx
  movzwl (%rdx),%edx
  movswl %dx,%edx
  sub    %edx,%eax
  mov    %eax,-0x24(%rbp)
  mov    -0x30(%rbp),%edx
  mov    -0x2c(%rbp),%eax
  add    %edx,%eax
  mov    %eax,-0x20(%rbp)
  mov    -0x24(%rbp),%edx
  mov    -0x28(%rbp),%eax
  add    %edx,%eax
  mov    %eax,-0x1c(%rbp)
  mov    -0x24(%rbp),%eax
  sub    -0x28(%rbp),%eax
  mov    %eax,-0x18(%rbp)
  mov    -0x30(%rbp),%eax
  sub    -0x2c(%rbp),%eax
  mov    %eax,-0x14(%rbp)
  mov    -0x20(%rbp),%eax
  shr    $0x1f,%eax
  movzbl %al,%eax
  add    %eax,-0x20(%rbp)
  mov    -0x1c(%rbp),%eax
  shr    $0x1f,%eax
  movzbl %al,%eax
  add    %eax,-0x1c(%rbp)
  mov    -0x18(%rbp),%eax
  shr    $0x1f,%eax
  movzbl %al,%eax
  add    %eax,-0x18(%rbp)
  mov    -0x14(%rbp),%eax
  shr    $0x1f,%eax
  movzbl %al,%eax
  add    %eax,-0x14(%rbp)
  mov    -0x20(%rbp),%eax
  add    $0x3,%eax
  sar    $0x3,%eax
  mov    %eax,%edx
  mov    -0x8(%rbp),%rax
  mov    %dx,(%rax)
  mov    -0x1c(%rbp),%eax
  add    $0x3,%eax
  sar    $0x3,%eax
  mov    %eax,%edx
  mov    -0x8(%rbp),%rax
  add    $0x8,%rax
  mov    %dx,(%rax)
  mov    -0x18(%rbp),%eax
  add    $0x3,%eax
  sar    $0x3,%eax
  mov    %eax,%edx
  mov    -0x8(%rbp),%rax
  add    $0x10,%rax
  mov    %dx,(%rax)
  mov    -0x14(%rbp),%eax
  add    $0x3,%eax
  sar    $0x3,%eax
  mov    %eax,%edx
  mov    -0x8(%rbp),%rax
  add    $0x18,%rax
  mov    %dx,(%rax)
  addq   $0x2,-0x10(%rbp)
  addq   $0x2,-0x8(%rbp)
  addl   $0x1,-0x34(%rbp)
L32:
  cmpl   $0x3,-0x34(%rbp)
  jle    L30
  nop
  nop
  pop    %rbp
  ret
```

assistant: ```c
void vp8_short_walsh4x4_c(short *input, short *output, int pitch) {
  int i;
  int a1, b1, c1, d1;
  int a2, b2, c2, d2;
  short *ip = input;
  short *op = output;
  for (i = 0; i < 4; i++) {
    a1 = ((ip[0] + ip[2]) << 2);
    d1 = ((ip[1] + ip[3]) << 2);
    c1 = ((ip[1] - ip[3]) << 2);
    b1 = ((ip[0] - ip[2]) << 2);
    op[0] = a1 + d1 + (a1 != 0);
    op[1] = b1 + c1;
    op[2] = b1 - c1;
    op[3] = a1 - d1;
    ip += pitch / 2;
    op += 4;
  }
  ip = output;
  op = output;
  for (i = 0; i < 4; i++) {
    a1 = ip[0] + ip[8];
    d1 = ip[4] + ip[12];
    c1 = ip[4] - ip[12];
    b1 = ip[0] - ip[8];
    a2 = a1 + d1;
    b2 = b1 + c1;
    c2 = b1 - c1;
    d2 = a1 - d1;
    a2 += a2 < 0;
    b2 += b2 < 0;
    c2 += c2 < 0;
    d2 += d2 < 0;
    op[0] = (a2 + 3) >> 3;
    op[4] = (b2 + 3) >> 3;
    op[8] = (c2 + 3) >> 3;
    op[12] = (d2 + 3) >> 3;
    ip++;
    op++;
  }
}
```