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| -rw-r--r-- | 2/6.c | 35 |
1 files changed, 35 insertions, 0 deletions
@@ -0,0 +1,35 @@ +#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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