user: 下面的汇编指令对应的C源代码是什么：

```asm
<drawBitmap2BPP>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    0x38(%rsp),%r10d
  mov    0x48(%rsp),%r14d
  mov    0x50(%rsp),%ebx
  mov    0x60(%rsp),%ebp
  movzbl 0x58(%rsp),%r11d
  sub    $0x1,%edx
  sar    $0x2,%edx
  lea    0x1(%rdx),%eax
  lea    (%r10,%r10,1),%ecx
  and    $0x6,%ecx
  mov    %r8d,%edx
  and    $0x1,%edx
  mov    %edx,-0x4(%rsp)
  mov    %eax,%edx
  imul   0x40(%rsp),%edx
  sar    $0x2,%r10d
  add    %r10d,%edx
  movslq %edx,%rdx
  lea    (%rsi,%rdx,1),%r13
  shl    $0x6,%r9d
  sar    %r8d
  lea    (%r9,%r8,1),%edx
  movslq %edx,%rdx
  lea    (%rdi,%rdx,1),%r12
  test   %ebx,%ebx
  jle    L39
  mov    %ebx,%esi
  shl    $0x6,%rsi
  lea    (%r12,%rsi,1),%r15
  cltq
  mov    %rax,-0x10(%rsp)
  jmp    L103
L109:
  movzbl (%r9),%ebx
  and    $0xf,%ebx
  shl    $0x4,%edi
  or     %ebx,%edi
  mov    %dil,(%r9)
L18:
  add    $0x2,%esi
  sar    $0x2,%al
  cmp    $0x6,%esi
  jle    L80
  movzbl 0x1(%r10),%eax
  lea    0x1(%r10),%r10
  mov    $0x0,%esi
L80:
  add    $0x1,%edx
  cmp    $0x1,%edx
  jle    L14
  add    $0x1,%r9
  mov    $0x0,%edx
L14:
  sub    $0x1,%r8d
  cmp    $0xffffffff,%r8d
  je     L31
L10:
  mov    %eax,%edi
  and    $0x3,%edi
  jne    L85
  test   %ebp,%ebp
  jne    L18
L85:
  test   %r11b,%r11b
  cmovns %r11d,%edi
  test   %edx,%edx
  jne    L109
  movzbl (%r9),%ebx
  and    $0xfffffff0,%ebx
  or     %ebx,%edi
  mov    %dil,(%r9)
  jmp    L18
L31:
  add    -0x10(%rsp),%r13
  add    $0x40,%r12
  cmp    %r12,%r15
  je     L39
L103:
  movsbl 0x0(%r13),%eax
  sar    %cl,%eax
  lea    -0x1(%r14),%r8d
  test   %r14d,%r14d
  jle    L31
  mov    -0x4(%rsp),%edx
  mov    %ecx,%esi
  mov    %r13,%r10
  mov    %r12,%r9
  jmp    L10
L39:
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void drawBitmap2BPP(char *buffer, char *bitmap, int bitmapWidth, int bitmapHeight, int destX, int destY, int sourceX, int sourceY, int width, int height, signed char shade, int isTransparent) {
  int startPos, startShift, widthLeft;
  char currentBitmap, currentShade;
  char *startBitmap, *startBuffer;
  int bitmapScanlineSkip = ((bitmapWidth - 1) >> 2) + 1;
  int bitmapShift = (sourceX & 0x03) << 1;
  int pixelPos = destX & 0x1;
  bitmap += (sourceY * bitmapScanlineSkip) + (sourceX >> 2);
  buffer += (destY << 6) + (destX >> 1);
  startShift = bitmapShift;
  startPos = pixelPos;
  startBitmap = bitmap;
  startBuffer = buffer;
  while (height-- > 0) {
    widthLeft = width;
    currentBitmap = *bitmap >> bitmapShift;
    while (widthLeft-- > 0) {
      currentShade = currentBitmap & 0x03;
      if (currentShade != 0 || !isTransparent) {
        if (shade >= 0)
          currentShade = shade;
        if (pixelPos == 0) {
          *buffer &= 0xF0;
          *buffer |= currentShade;
        } else {
          *buffer &= 0x0F;
          *buffer |= currentShade << 4;
        }
      }
      bitmapShift += 2;
      if (bitmapShift > 6) {
        bitmapShift = 0;
        currentBitmap = *(++bitmap);
      } else
        currentBitmap >>= 2;
      if (++pixelPos > 1) {
        buffer++;
        pixelPos = 0;
      }
    }
    bitmapShift = startShift;
    startBitmap += bitmapScanlineSkip;
    bitmap = startBitmap;
    pixelPos = startPos;
    startBuffer += 64;
    buffer = startBuffer;
  }
}
```