memcpy数据复制粘贴的展开加速

eric2013

memcpy(frame, src, len)

展开：

1. /* Fast-copy data to frame buffer */
   
2.   for ( ; len > 7U; frame += 8, src += 8, len -= 8U) {
   
3.     __UNALIGNED_UINT32_WRITE(&frame[0], __UNALIGNED_UINT32_READ(&src[0]));
   
4.     __UNALIGNED_UINT32_WRITE(&frame[4], __UNALIGNED_UINT32_READ(&src[4]));
   
5.   }
   
6.   /* Copy remaining 7 bytes */
   
7.   for ( ; len > 1U; frame += 2, src += 2, len -= 2U) {
   
8.     __UNALIGNED_UINT16_WRITE(&frame[0], __UNALIGNED_UINT16_READ(&src[0]));
   
9.   }
   
10.   if (len > 0U) { frame[0] = src[0]; }

复制代码

emwin

32位MCU里memcpy速度上限也就32位复制的速度