user: Demonstrate the C code that generates the assembly output below:

```asm
<fill_blank_frame>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x20,%rsp
  mov    %rdi,-0x18(%rbp)
  mov    %esi,-0x1c(%rbp)
  mov    %edx,-0x20(%rbp)
  cmpl   $0x59565955,-0x20(%rbp)
  je     L49
  cmpl   $0x59565955,-0x20(%rbp)
  jg     L8
  cmpl   $0x47504a4d,-0x20(%rbp)
  je     L53
  cmpl   $0x47504a4d,-0x20(%rbp)
  jg     L8
  cmpl   $0x32595559,-0x20(%rbp)
  je     L1
  cmpl   $0x32595559,-0x20(%rbp)
  jg     L8
  cmpl   $0x30323449,-0x20(%rbp)
  je     L33
  cmpl   $0x32315659,-0x20(%rbp)
  jne    L8
  mov    -0x1c(%rbp),%eax
  shl    $0x2,%eax
  movslq %eax,%rdx
  imul   $0x2aaaaaab,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x1f,%eax
  sub    %eax,%edx
  mov    -0x18(%rbp),%rax
  mov    $0x29,%esi
  mov    %rax,%rdi
  call   <memset@plt>
  mov    -0x1c(%rbp),%eax
  movslq %eax,%rdx
  imul   $0x2aaaaaab,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x1f,%eax
  sub    %eax,%edx
  mov    -0x1c(%rbp),%eax
  shl    $0x2,%eax
  movslq %eax,%rcx
  imul   $0x2aaaaaab,%rcx,%rcx
  shr    $0x20,%rcx
  sar    $0x1f,%eax
  mov    %eax,%esi
  mov    %ecx,%eax
  sub    %esi,%eax
  movslq %eax,%rcx
  mov    -0x18(%rbp),%rax
  add    %rcx,%rax
  mov    $0x6e,%esi
  mov    %rax,%rdi
  call   <memset@plt>
  mov    -0x1c(%rbp),%eax
  movslq %eax,%rdx
  imul   $0x2aaaaaab,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x1f,%eax
  sub    %eax,%edx
  mov    -0x1c(%rbp),%ecx
  mov    %ecx,%eax
  shl    $0x2,%eax
  add    %ecx,%eax
  movslq %eax,%rcx
  imul   $0x2aaaaaab,%rcx,%rcx
  shr    $0x20,%rcx
  sar    $0x1f,%eax
  mov    %eax,%esi
  mov    %ecx,%eax
  sub    %esi,%eax
  movslq %eax,%rcx
  mov    -0x18(%rbp),%rax
  add    %rcx,%rax
  mov    $0xf0,%esi
  mov    %rax,%rdi
  call   <memset@plt>
  jmp    L123
L33:
  mov    -0x1c(%rbp),%eax
  shl    $0x2,%eax
  movslq %eax,%rdx
  imul   $0x2aaaaaab,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x1f,%eax
  sub    %eax,%edx
  mov    -0x18(%rbp),%rax
  mov    $0x29,%esi
  mov    %rax,%rdi
  call   <memset@plt>
  mov    -0x1c(%rbp),%eax
  movslq %eax,%rdx
  imul   $0x2aaaaaab,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x1f,%eax
  sub    %eax,%edx
  mov    -0x1c(%rbp),%eax
  shl    $0x2,%eax
  movslq %eax,%rcx
  imul   $0x2aaaaaab,%rcx,%rcx
  shr    $0x20,%rcx
  sar    $0x1f,%eax
  mov    %eax,%esi
  mov    %ecx,%eax
  sub    %esi,%eax
  movslq %eax,%rcx
  mov    -0x18(%rbp),%rax
  add    %rcx,%rax
  mov    $0xf0,%esi
  mov    %rax,%rdi
  call   <memset@plt>
  mov    -0x1c(%rbp),%eax
  movslq %eax,%rdx
  imul   $0x2aaaaaab,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x1f,%eax
  sub    %eax,%edx
  mov    -0x1c(%rbp),%ecx
  mov    %ecx,%eax
  shl    $0x2,%eax
  add    %ecx,%eax
  movslq %eax,%rcx
  imul   $0x2aaaaaab,%rcx,%rcx
  shr    $0x20,%rcx
  sar    $0x1f,%eax
  mov    %eax,%esi
  mov    %ecx,%eax
  sub    %esi,%eax
  movslq %eax,%rcx
  mov    -0x18(%rbp),%rax
  add    %rcx,%rax
  mov    $0x6e,%esi
  mov    %rax,%rdi
  call   <memset@plt>
  jmp    L123
L49:
  movl   $0x0,-0x4(%rbp)
  jmp    L138
L126:
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0xff,(%rax)
  mov    -0x4(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  mov    -0x4(%rbp),%eax
  cltq
  lea    0x2(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  mov    -0x4(%rbp),%eax
  cltq
  lea    0x3(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  addl   $0x4,-0x4(%rbp)
L138:
  mov    -0x4(%rbp),%eax
  cmp    -0x1c(%rbp),%eax
  jl     L126
  jmp    L123
L1:
  movl   $0x0,-0x4(%rbp)
  jmp    L65
L48:
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  mov    -0x4(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0xff,(%rax)
  mov    -0x4(%rbp),%eax
  cltq
  lea    0x2(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  mov    -0x4(%rbp),%eax
  cltq
  lea    0x3(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  addl   $0x4,-0x4(%rbp)
L65:
  mov    -0x4(%rbp),%eax
  cmp    -0x1c(%rbp),%eax
  jl     L48
  jmp    L123
L8:
  mov    -0x1c(%rbp),%edx
  mov    -0x18(%rbp),%rax
  mov    $0xc0,%esi
  mov    %rax,%rdi
  call   <memset@plt>
  jmp    L123
L53:
  nop
L123:
  nop
  leave
  ret
```

assistant: ```c
void fill_blank_frame(char *buffer, int len, int fmt) {
  int i;
  switch (fmt) {
  case (('Y') | (('V') << 8) | (('1') << 16) | ((unsigned)('2') << 24)):
    memset(buffer, 41, 4 * len / 6);
    memset(buffer + 4 * len / 6, 110, len / 6);
    memset(buffer + 5 * len / 6, 240, len / 6);
    break;
  case (('I') | (('4') << 8) | (('2') << 16) | ((unsigned)('0') << 24)):
    memset(buffer, 41, 4 * len / 6);
    memset(buffer + 4 * len / 6, 240, len / 6);
    memset(buffer + 5 * len / 6, 110, len / 6);
    break;
  case (('U') | (('Y') << 8) | (('V') << 16) | ((unsigned)('Y') << 24)):
    for (i = 0; i < len; i += 4) {
      buffer[i] = 0xFF;
      buffer[i + 1] = 0;
      buffer[i + 2] = 0;
      buffer[i + 3] = 0;
    }
    break;
  case (('Y') | (('U') << 8) | (('Y') << 16) | ((unsigned)('2') << 24)):
    for (i = 0; i < len; i += 4) {
      buffer[i] = 0;
      buffer[i + 1] = 0xFF;
      buffer[i + 2] = 0;
      buffer[i + 3] = 0;
    }
    break;
  case (('M') | (('J') << 8) | (('P') << 16) | ((unsigned)('G') << 24)):
    break;
  default:
    memset(buffer, 0xC0, len);
  }
}
```