rms c语言 函数,C中任何更快的RMS值计算？

我正在用C编写一个小型8位微控制器的软件.部分代码是读取电流互感器(ZCT)的ADC值,然后计算RMS值.流过ZCT的电流是正弦曲线但可能会失真.我的代码如下：

float adc_value, inst_current;

float acc_load_current; // accumulator = (I1*I1 + I2*I2 + ... + In*In)

double rms_current;

// Calculate the real instantanous value from the ADC reading

inst_current = (adc_value/1024)*2.5; // 10bit ADC, Voltage ref. 2.5V, so formula is: x=(adc/1024)*2.5V

// Update the RMS value with the new instananous value:

// Substract 1 sample from the accumulator (sample size is 512, so divide accumulator by 512 and substract it from the accumulator)

acc_load_current -= (acc_load_current / 512);

inst_current *= inst_current; // square the instantanous current

acc_load_current += inst_current; // Add it to the accumulator

rms_current = (acc_load_current / 512); // Get the mean square value. (sample size is 512)

rms_current = sqrt(rms_current); // Get RMS value

// Now the < rms_current > is the real RMS current

但是,它有许多浮点计算.这给我的小型MCU增加了很大的负担.我发现sqrt()函数在我的编译器中不起作用.

有没有可以运行得更快的代码？