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/***
*rotr.c - rotate an unsigned integer right
*
* Copyright (c) 1989-1991, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines _rotr() - performs a rotate right on an unsigned integer.
*
*Revision History:
* 06-02-89 PHG Module created
* 11-03-89 JCR Added _lrotl
* 03-15-90 GJF Made calling type _CALLTYPE1, added #include
* <cruntime.h> and fixed the copyright. Also, cleaned
* up the formatting a bit.
* 10-04-90 GJF New-style function declarators.
* 04-01-91 SRW Enable #pragma function for i386 _WIN32_ builds too.
* 09-02-92 GJF Don't build for POSIX.
* 03-09-94 RDL Enable #pragma function for i386 _WIN32_ builds too.
*
*******************************************************************************/
#ifndef _POSIX_
#include <cruntime.h>
#include <stdlib.h>
#include <limits.h>
#ifdef _MSC_VER
#pragma function(_lrotr,_rotr)
#endif
#if UINT_MAX != 0xffffffff
#error This module assumes 32-bit integers
#endif
#if (UINT_MAX != ULONG_MAX)
#error This module assumes sizeof(int) == sizeof(long)
#endif
/***
*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 values
*
*Exceptions:
* None.
*
*******************************************************************************/
unsigned long _CALLTYPE1 _lrotr (
unsigned long val,
int shift
)
{
return( (unsigned long) _rotr((unsigned) val, shift) );
}
unsigned _CALLTYPE1 _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;
}
#endif
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