user: 提供的汇编代码用C语言表示会是什么样子:

```asm
<pack_dxt>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0xf8,%rsp
  mov    %rdi,%r15
  mov    %rsi,0x48(%rsp)
  mov    %fs:0x28,%rax
  mov    %rax,0xe8(%rsp)
  xor    %eax,%eax
  mov    (%rdi),%rcx
  and    $0xf8fcf8,%ecx
  lea    0x8(%rdi),%rsi
  lea    0x80(%rdi),%rdi
  mov    $0x0,%ebx
  jmp    L84
L89:
  mov    $0x0,%eax
L21:
  add    $0x8,%rsi
L84:
  cmp    %eax,%ebx
  je     L86
L155:
  cmp    %rdi,%rsi
  je     L121
  mov    (%rsi),%rcx
  and    $0xf8fcf8,%ecx
  test   %ebx,%ebx
  jle    L89
  lea    0x60(%rsp),%rdx
  mov    $0x0,%eax
L124:
  cmp    (%rdx),%rcx
  je     L21
  add    $0x1,%eax
  add    $0x8,%rdx
  cmp    %eax,%ebx
  jne    L124
  mov    %ebx,%eax
  jmp    L21
L86:
  movslq %ebx,%rax
  mov    %rcx,0x60(%rsp,%rax,8)
  lea    0x1(%rbx),%ebx
  jmp    L155
L121:
  cmp    $0x1,%ebx
  je     L110
  jle    L45
  lea    0x60(%rsp),%rsi
  mov    %rsi,0x38(%rsp)
  lea    -0x2(%rbx),%eax
  add    $0x2,%rax
  mov    %rax,0x30(%rsp)
  mov    %rsi,(%rsp)
  movq   $0x1,0x28(%rsp)
  mov    $0x40000000,%r14d
  lea    -0x1(%rbx),%eax
  mov    %eax,0x44(%rsp)
  mov    %ebx,0x40(%rsp)
  jmp    L69
L110:
  mov    0x60(%rsp),%rax
  mov    %rax,0x10(%rsp)
  mov    %rax,0x18(%rsp)
  movl   $0x3,0x24(%rsp)
L45:
  mov    0x10(%rsp),%rdi
  mov    %edi,%eax
  shr    $0xa,%ax
  shl    $0x5,%eax
  mov    %rdi,%rdx
  shr    $0x13,%rdx
  shl    $0xb,%edx
  add    %edx,%eax
  mov    %edi,%edx
  shr    $0x3,%dl
  movzbl %dl,%edx
  add    %edx,%eax
  mov    0x48(%rsp),%r9
  mov    %ax,(%r9)
  mov    0x18(%rsp),%rbx
  mov    %ebx,%edx
  shr    $0xa,%dx
  shl    $0x5,%edx
  mov    %rbx,%rcx
  shr    $0x13,%rcx
  shl    $0xb,%ecx
  add    %ecx,%edx
  mov    %ebx,%ecx
  shr    $0x3,%cl
  movzbl %cl,%ecx
  add    %ecx,%edx
  mov    %dx,0x2(%r9)
  cmp    %dx,%ax
  seta   %sil
  cmpl   $0x3,0x24(%rsp)
  sete   %cl
  cmp    %cl,%sil
  je     L81
  mov    %dx,(%r9)
  mov    %ax,0x2(%r9)
  mov    %rbx,0x10(%rsp)
  mov    %rdi,0x18(%rsp)
L81:
  mov    0x48(%rsp),%r8
  add    $0x4,%r8
  mov    0x18(%rsp),%rcx
  mov    0x10(%rsp),%rdx
  mov    0x24(%rsp),%esi
  mov    %r15,%rdi
  call   <score_dxt@plt>
  mov    0xe8(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L187
  add    $0xf8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L175:
  add    $0x8,%rbx
  cmp    %rbx,0x8(%rsp)
  je     L63
L73:
  mov    0x8(%rbx),%r12
  mov    (%rsp),%rax
  mov    (%rax),%rbp
  mov    %r13,%r8
  mov    %r12,%rcx
  mov    %rbp,%rdx
  mov    $0x2,%esi
  mov    %r15,%rdi
  call   <score_dxt@plt>
  cmp    %r14d,%eax
  jge    L24
  mov    %r12,0x18(%rsp)
  mov    %rbp,0x10(%rsp)
  mov    %eax,%r14d
  movl   $0x2,0x24(%rsp)
L24:
  mov    %r13,%r8
  mov    %r12,%rcx
  mov    %rbp,%rdx
  mov    $0x3,%esi
  mov    %r15,%rdi
  call   <score_dxt@plt>
  cmp    %eax,%r14d
  jle    L175
  mov    %r12,0x18(%rsp)
  mov    %rbp,0x10(%rsp)
  mov    %eax,%r14d
  movl   $0x3,0x24(%rsp)
  jmp    L175
L63:
  addq   $0x1,0x28(%rsp)
  mov    0x28(%rsp),%rax
  addq   $0x8,(%rsp)
  cmp    0x30(%rsp),%rax
  je     L45
L69:
  mov    0x28(%rsp),%rdi
  cmp    %edi,0x40(%rsp)
  jle    L63
  mov    0x44(%rsp),%eax
  sub    %edi,%eax
  lea    -0x1(%rdi,%rax,1),%rax
  mov    0x38(%rsp),%rdi
  lea    0x8(%rdi,%rax,8),%rax
  mov    %rax,0x8(%rsp)
  mov    (%rsp),%rbx
  lea    0x58(%rsp),%r13
  jmp    L73
L187:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void pack_dxt(unsigned long *px, unsigned char *dest) {
  int i1, i2, best_ninter, err, best_err, ncolors;
  unsigned long uniq[16];
  unsigned long col1, col2, best_col1, best_col2, pack;
  unsigned char *c1, *c2;
  unsigned short *sptr, tmpshort;
  ncolors = 0;
  for (i1 = 0; i1 < 16; i1++) {
    col1 = px[i1] & 0xf8fcf8;
    for (i2 = 0; i2 < ncolors; i2++)
      if (uniq[i2] == col1)
        break;
    if (i2 == ncolors)
      uniq[ncolors++] = col1;
  }
  if (ncolors == 1) {
    best_col1 = uniq[0];
    best_col2 = uniq[0];
    best_err = 1000;
    best_ninter = 3;
  } else {
    best_err = (1 << 30);
    for (i1 = 0; i1 < ncolors - 1; i1++)
      for (i2 = i1 + 1; i2 < ncolors; i2++) {
        err = score_dxt(px, 2, uniq[i1], uniq[i2], &pack);
        if (err < best_err) {
          best_col1 = uniq[i1];
          best_col2 = uniq[i2];
          best_ninter = 2;
          best_err = err;
        }
        err = score_dxt(px, 3, uniq[i1], uniq[i2], &pack);
        if (err < best_err) {
          best_col1 = uniq[i1];
          best_col2 = uniq[i2];
          best_ninter = 3;
          best_err = err;
        }
      }
  }
  c1 = (unsigned char *)&col1;
  c2 = (unsigned char *)&col2;
  col1 = best_col1;
  col2 = best_col2;
  sptr = (unsigned short *)dest;
  sptr[0] = ((unsigned short)c1[0] >> 3) + (((unsigned short)c1[1] >> 2) << 5) + (((unsigned short)c1[2] >> 3) << 11);
  sptr[1] = ((unsigned short)c2[0] >> 3) + (((unsigned short)c2[1] >> 2) << 5) + (((unsigned short)c2[2] >> 3) << 11);
  if ((sptr[0] > sptr[1]) ^ (best_ninter == 3)) {
    tmpshort = sptr[0];
    sptr[0] = sptr[1];
    sptr[1] = tmpshort;
    best_col1 = col2;
    best_col2 = col1;
  }
  score_dxt(px, best_ninter, best_col1, best_col2, (unsigned long *)(dest + 4));
}
```