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

```asm
<decode_dxt1_block>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x60,%rsp
  mov    %rdi,-0x58(%rbp)
  mov    %rsi,-0x60(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  mov    -0x58(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,-0x28(%rbp)
  mov    -0x58(%rbp),%rax
  mov    0x8(%rax),%eax
  mov    %eax,-0x24(%rbp)
  lea    -0x40(%rbp),%rcx
  lea    -0x44(%rbp),%rdx
  lea    -0x48(%rbp),%rsi
  mov    -0x28(%rbp),%eax
  mov    %eax,%edi
  call   <rgb565_le@plt>
  lea    -0x34(%rbp),%rcx
  lea    -0x38(%rbp),%rdx
  lea    -0x3c(%rbp),%rsi
  mov    -0x24(%rbp),%eax
  mov    %eax,%edi
  call   <rgb565_le@plt>
  movq   $0x0,-0x20(%rbp)
  movq   $0x0,-0x18(%rbp)
  mov    -0x40(%rbp),%edx
  mov    -0x44(%rbp),%esi
  mov    -0x48(%rbp),%eax
  mov    $0xff,%ecx
  mov    %eax,%edi
  call   <color@plt>
  mov    %eax,-0x20(%rbp)
  mov    -0x34(%rbp),%edx
  mov    -0x38(%rbp),%esi
  mov    -0x3c(%rbp),%eax
  mov    $0xff,%ecx
  mov    %eax,%edi
  call   <color@plt>
  mov    %eax,-0x1c(%rbp)
  mov    -0x28(%rbp),%eax
  cmp    -0x24(%rbp),%eax
  jle    L35
  mov    -0x40(%rbp),%eax
  lea    (%rax,%rax,1),%edx
  mov    -0x34(%rbp),%eax
  add    %edx,%eax
  movslq %eax,%rdx
  imul   $0x55555556,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x1f,%eax
  sub    %eax,%edx
  mov    -0x44(%rbp),%eax
  lea    (%rax,%rax,1),%ecx
  mov    -0x38(%rbp),%eax
  add    %ecx,%eax
  movslq %eax,%rcx
  imul   $0x55555556,%rcx,%rcx
  shr    $0x20,%rcx
  sar    $0x1f,%eax
  mov    %ecx,%esi
  sub    %eax,%esi
  mov    -0x48(%rbp),%eax
  lea    (%rax,%rax,1),%ecx
  mov    -0x3c(%rbp),%eax
  add    %ecx,%eax
  movslq %eax,%rcx
  imul   $0x55555556,%rcx,%rcx
  shr    $0x20,%rcx
  sar    $0x1f,%eax
  mov    %eax,%edi
  mov    %ecx,%eax
  sub    %edi,%eax
  mov    $0xff,%ecx
  mov    %eax,%edi
  call   <color@plt>
  mov    %eax,-0x18(%rbp)
  mov    -0x34(%rbp),%eax
  lea    (%rax,%rax,1),%edx
  mov    -0x40(%rbp),%eax
  add    %edx,%eax
  movslq %eax,%rdx
  imul   $0x55555556,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x1f,%eax
  sub    %eax,%edx
  mov    -0x38(%rbp),%eax
  lea    (%rax,%rax,1),%ecx
  mov    -0x44(%rbp),%eax
  add    %ecx,%eax
  movslq %eax,%rcx
  imul   $0x55555556,%rcx,%rcx
  shr    $0x20,%rcx
  sar    $0x1f,%eax
  mov    %ecx,%esi
  sub    %eax,%esi
  mov    -0x3c(%rbp),%eax
  lea    (%rax,%rax,1),%ecx
  mov    -0x48(%rbp),%eax
  add    %ecx,%eax
  movslq %eax,%rcx
  imul   $0x55555556,%rcx,%rcx
  shr    $0x20,%rcx
  sar    $0x1f,%eax
  mov    %eax,%edi
  mov    %ecx,%eax
  sub    %edi,%eax
  mov    $0xff,%ecx
  mov    %eax,%edi
  call   <color@plt>
  mov    %eax,-0x14(%rbp)
  jmp    L45
L35:
  mov    -0x40(%rbp),%edx
  mov    -0x34(%rbp),%eax
  add    %edx,%eax
  mov    %eax,%edx
  shr    $0x1f,%edx
  add    %edx,%eax
  sar    %eax
  mov    %eax,%edx
  mov    -0x44(%rbp),%ecx
  mov    -0x38(%rbp),%eax
  add    %ecx,%eax
  mov    %eax,%ecx
  shr    $0x1f,%ecx
  add    %ecx,%eax
  sar    %eax
  mov    %eax,%esi
  mov    -0x48(%rbp),%ecx
  mov    -0x3c(%rbp),%eax
  add    %ecx,%eax
  mov    %eax,%ecx
  shr    $0x1f,%ecx
  add    %ecx,%eax
  sar    %eax
  mov    $0xff,%ecx
  mov    %eax,%edi
  call   <color@plt>
  mov    %eax,-0x18(%rbp)
  mov    $0xff,%ecx
  mov    $0x0,%edx
  mov    $0x0,%esi
  mov    $0x0,%edi
  call   <color@plt>
  mov    %eax,-0x14(%rbp)
L45:
  mov    -0x58(%rbp),%rax
  mov    0x10(%rax),%eax
  mov    %eax,-0x30(%rbp)
  movl   $0x0,-0x2c(%rbp)
  jmp    L29
L30:
  mov    -0x30(%rbp),%eax
  and    $0x3,%eax
  mov    %eax,%ecx
  mov    -0x2c(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x60(%rbp),%rax
  add    %rax,%rdx
  movslq %ecx,%rax
  mov    -0x20(%rbp,%rax,4),%eax
  mov    %eax,(%rdx)
  addl   $0x1,-0x2c(%rbp)
  sarl   $0x2,-0x30(%rbp)
L29:
  cmpl   $0xf,-0x2c(%rbp)
  jle    L30
  nop
  mov    -0x8(%rbp),%rax
  sub    %fs:0x28,%rax
  je     L6
  call   <__stack_chk_fail@plt>
L6:
  leave
  ret
```

assistant: ```c
void decode_dxt1_block(const uint8_t *data, uint32_t *outbuf) {
  uint8_t r0, g0, b0, r1, g1, b1;
  int q0 = *(uint16_t *)(data);
  int q1 = *(uint16_t *)(data + 2);
  rgb565_le(q0, &r0, &g0, &b0);
  rgb565_le(q1, &r1, &g1, &b1);
  uint_fast32_t c[4] = {color(r0, g0, b0, 255), color(r1, g1, b1, 255)};
  if (q0 > q1) {
    c[2] = color((r0 * 2 + r1) / 3, (g0 * 2 + g1) / 3, (b0 * 2 + b1) / 3, 255);
    c[3] = color((r0 + r1 * 2) / 3, (g0 + g1 * 2) / 3, (b0 + b1 * 2) / 3, 255);
  } else {
    c[2] = color((r0 + r1) / 2, (g0 + g1) / 2, (b0 + b1) / 2, 255);
    c[3] = color(0, 0, 0, 255);
  }
  uint_fast32_t d = (*(uint32_t *)(data + 4));
  for (int i = 0; i < 16; i++, d >>= 2)
    outbuf[i] = c[d & 3];
}
```