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- 1970-1-1
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a0a.1 32b0c
前提条件:stm32F407已经开启FPU;发现下面两段代码的运算所用时间相同:
代码一、
uint32_t kmm3 = 4521,kmm4 = 2145;
uint32_t kkkk;
kkkk = (int32_t)(kmm3 * kmm4);
kkkk = (int32_t)(kmm3 * kmm4);
kkkk = (int32_t)(kmm3 * kmm4);
kkkk = (int32_t)(kmm3 * kmm4);
kkkk = (int32_t)(kmm3 * kmm4);
kkkk = (int32_t)(kmm3 * kmm4);
kkkk = (int32_t)(kmm3 * kmm4);
kkkk = (int32_t)(kmm3 * kmm4);
代码二、
float32_t mmmm;
float32_t kmm1=4521.0, kmm2=2145.0;
mmmm = (float32_t)(kmm1 * kmm2);
mmmm = (float32_t)(kmm1 * kmm2);
mmmm = (float32_t)(kmm1 * kmm2);
mmmm = (float32_t)(kmm1 * kmm2);
mmmm = (float32_t)(kmm1 * kmm2);
mmmm = (float32_t)(kmm1 * kmm2);
mmmm = (float32_t)(kmm1 * kmm2);
mmmm = (float32_t)(kmm1 * kmm2);
问题:在stm32F407中运算单精度浮点型的乘法与整数型的乘法所用的周期数相同?怎么跟资料不同。是我哪里弄错了?请大虾指教。万分感谢!!!
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