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_rotl8, _rotl16

Microsoft Specific

Rotate the input values to the left to the most significant bit (MSB) by a specified number of bit positions.


unsigned char _rotl8( 
   unsigned char value, 
   unsigned char shift 
);
unsigned short _rotl16( 
   unsigned short value, 
   unsigned char shift 
);

Parameters

[in] value

The value to rotate.

[in] shift

The number of bits to rotate.

The rotated value.

Intrinsic Architecture

_rotl8

x86, IPF, x64

_rotl16

x86, IPF, x64

Header file <intrin.h>

Unlike a left-shift operation, when executing a left rotation, the high order bits that fall off the high end are moved into the least significant bit positions.

// rotl.cpp
#include <stdio.h>
#include <intrin.h>

#pragma intrinsic(_rotl8, _rotl16)

int main()
{
    unsigned char c = 'A', c1, c2;

    for (int i = 0; i < 8; i++)
    {
       printf_s("Rotating 0x%x left by %d bits gives 0x%x\n", c,
               i, _rotl8(c, i));
    }

    unsigned short s = 0x12;
    int nBit = 10;

    printf_s("Rotating unsigned short 0x%x left by %d bits gives 0x%x\n",
            s, nBit, _rotl16(s, nBit));
}

Output

Rotating 0x41 left by 0 bits gives 0x41
Rotating 0x41 left by 1 bits gives 0x82
Rotating 0x41 left by 2 bits gives 0x5
Rotating 0x41 left by 3 bits gives 0xa
Rotating 0x41 left by 4 bits gives 0x14
Rotating 0x41 left by 5 bits gives 0x28
Rotating 0x41 left by 6 bits gives 0x50
Rotating 0x41 left by 7 bits gives 0xa0
Rotating unsigned short 0x12 left by 10 bits gives 0x4800

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