Chapter 11, Problem 6E

Write a function called b that looks for the occurrence of a specified pattern of bits inside an u . The function should take three arguments and should be called as shown:

b

The function searches the integer s , starting at the leftmost bit, to see if the rightmost n bits of p occur in s , If the pattern is found, have the function return the number of the bit at which the pattern begins, where the leftmost bit is bit number 0. If the pattern is not found, then have the function return -1. So, for example, the call

i

causes the b function to search the number 0xelf4( = 1110 0001 1111 0100 binary) for the occurrence of the three-bit pattern 0x5 (= 101 binary). The function returns 1 to indicate that the pattern was found in the source beginning with bit number 1 .

Make certain that the function makes no assumptions about the size of an i (see exercise 3 in this chapter).