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#include <stdio.h>
unsigned setbits(unsigned x, int p, int n, unsigned y);
int main(int argc, char *argv[]) {
int p, n;
unsigned x, y;
p = 5;
n = 3;
x = 0;
y = 7;
printf("New bit field: %x\n", setbits(x, p, n, y));
return 0;
}
unsigned setbits(unsigned x, int p, int n, unsigned y) {
unsigned yLO, yLOA, xUnset, xPrime;
// extract LO n bits from y
yLO = y & ~(~0 << n);
// align extracted LO bits of y to position p:
yLOA = yLO << (p + 1 - n);
// create mask with n bits from position p unset:
xUnset = (~0 << p) | ~(~0 << (p - n));
// mask out n bits from x starting at position p:
xPrime = x & xUnset;
return xPrime | yLOA;
}
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