AVRStudio 6 delay函数错误的解决方法

之前一直用winavr作为avr开发工具,AVRstudio 5以后的版本直接包含了GCCAVR工具链,开发环境也变化比较大,总体还是非常给力的,所以一直跟着版本更新,原来的程序直接拷贝编译无法通过,出现最多的是这个错误:
错误 __builtin_avr_delay_cycles expects an integer constant.
经过查找发现是头文件版本更新所致 。delay.h文件214行说明如下:
Note: The new implementation of _delay_us(double __us) with
__builtin_avr_delay_cycles(unsigned long) support is not backward compatible.
User can define __DELAY_BACKWARD_COMPATIBLE__ to get a backward compatible delay.
Also, the backward compatible
algorithm will be chosen if the code is compiLED in a

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