/*** *rotr.c - rotate an unsigned integer right * * Copyright (c) 1989-1997, Microsoft Corporation. All rights reserved. * *Purpose: * defines _rotr() - performs a rotate right on an unsigned integer. * *******************************************************************************/ /*** *unsigned _rotr(val, shift) - int rotate right * *Purpose: * Performs a rotate right on an unsigned integer. * * [Note: The _lrotl entry is based on the assumption * that sizeof(int) == sizeof(long).] *Entry: * unsigned val: value to rotate * int shift: number of bits to shift by * *Exit: * returns rotated value * *Exceptions: * None. * *******************************************************************************/ unsigned rotr(unsigned val, int shift) { register unsigned lobit; /* non-zero means lo bit set */ register unsigned num = val; /* number to rotate */ shift &= 0x1f; /* modulo 32 -- this will also make negative shifts work */ while(shift--) { lobit = num & 1; /* get high bit */ num >>= 1; /* shift right one bit */ if(lobit) num |= 0x80000000; /* set hi bit if lo bit was set */ } return num; }