/*** *rotl.c - rotate an unsigned integer left * * Copyright (c) 1989-1997, Microsoft Corporation. All rights reserved. * *Purpose: * defines _rotl() - performs a rotate left on an unsigned integer. * *******************************************************************************/ /*** *unsigned _rotl(val, shift) - int rotate left * *Purpose: * Performs a rotate left 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 rotl(unsigned val, int shift) { register unsigned hibit; /* non-zero means hi bit set */ register unsigned num = val; /* number to rotate */ shift &= 0x1f; /* modulo 32 -- this will also make negative shifts work */ while(shift--) { hibit = num & 0x80000000; /* get high bit */ num <<= 1; /* shift left one bit */ if(hibit) num |= 1; /* set lo bit if hi bit was set */ } return num; }