`map' macro in c-language from arduino

map.c

// `map' function from arduino
//
// thx to "http://www.musashinodenpa.com/arduino/ref/index.php?f=0&pos=2743"

#include <stdio.h>

#define MAP(x, in_min, in_max, out_min, out_max) \
    ((x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min)

typedef __int16_t int16_t;

int main(void)
{
    int16_t a[] = {-800, 800, 0, 1023, -1023};

    for(unsigned long i=0; i<(sizeof(a)/sizeof(a[0])); i++) {
        int16_t x = a[i];
        printf("%d: %d\n", x, MAP(x, -1023, 1023, -127, 127));
    }
}

/* result

~/Dropbox/test/c ❯❯❯ ./a.out
-800: -100
800: 99
0: 0
1023: 127
-1023: -127

*/