kdeng00
54 lines
1.2 KiB
C
54 lines
1.2 KiB
C
/*
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*
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* Exercise 2-8. Write a function rightrot(x,n) that returns the value of the integer x
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* rotated to the right by n positions.
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*
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* Author: Kun Deng
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <limits.h>
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// Returns the value of the integer x rotated to the right by n positions
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unsigned int rightrot(unsigned int x, int n);
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int main(int argc, char **argv)
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{
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unsigned int x = 511;
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int n = 3;
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if (argc == 3)
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{
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x = atoi(argv[1]);
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n = atoi(argv[2]);
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}
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unsigned int rotated = rightrot(x, n);
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printf("rightrot(%d, %d)", x, n);
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printf(" = %u\n", rotated);
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return 0;
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}
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unsigned int rightrot(unsigned int x, int n)
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{
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unsigned int some_bits = CHAR_BIT * sizeof(x) - 1;
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printf("size of x is %ld some_bits = %d\n", sizeof(x), some_bits);
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unsigned int off = n & some_bits;
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printf("off is %d\n", off);
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printf("(%d >> %d) | (%d << (%d & %d))\n", x, off, x, off, some_bits);
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printf("(%d >> %d) | (%d << %d)\n", x, off, x, (off && some_bits));
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printf("%d | %d\n", (x >> off), (x << (off && some_bits)));
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unsigned int rotated = (x >> off) | (x << (off & some_bits));
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return rotated;
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}
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