Execution times: sqrt() and other library functions

Hi Leighton,

The compiler libraries do not include benchmarks for any of the RTS math functions but it's easy to benchmark them using a timer. The code below gives a short example of how you can benchmark both the "math.h" and hidden math functions for the EABI functions.

#include <msp430.h> 

#include <stdint.h>
#include <math.h>

#define startBench()    TA0CTL = TACLR;TA0CTL = TASSEL_2 + MC_2
#define stopBench()     TA0CTL = MC_0
#define getBench()      TA0R

volatile uint16_t cycles;

extern float __mspabi_divf(float, float);

int main(void)
{
    uint16_t delay;
    float res;

    WDTCTL = WDTPW | WDTHOLD;    // Stop watchdog timer

    /* Calculate delay of starting and stopping the counter. */
    startBench();
    stopBench();
    delay = getBench();

    /* Example benchmark of CCS math function */
    startBench();
    res = sqrtf(1.0);
    stopBench();
    cycles = getBench() - delay;

    /* Example benchmark of CCS RTS function */
    startBench();
    res = __mspabi_divf(1.0, 2.0);
    stopBench();
    cycles = getBench() - delay;

    return 0;
}

If you are interested in improved math performance on MSP430 I suggest checking out the IQmathLib which provides optimized fixed point math functions. For more information you can check out the IQmathLib page or download MSPware.

Regards,

Brent Peterson