core.bitop

pure nothrow @nogc @safe int bsf(size_t v);

Scans the bits in v starting with bit 0, looking for the first set bit.

Returns:

The bit number of the first bit set. The return value is undefined if v is zero.

Example:

import core.bitop;

int main()
{
    assert(bsf(0x21) == 0);
    return 0;
}

pure nothrow @nogc @safe int bsr(size_t v);

Scans the bits in v from the most significant bit to the least significant bit, looking for the first set bit.

Returns:

The bit number of the first bit set. The return value is undefined if v is zero.

Example:

import core.bitop;

int main()
{
    assert(bsr(0x21) == 5);
    return 0;
}

pure nothrow @nogc @system int bt(in size_t* p, size_t bitnum);

Tests the bit. (No longer an intrisic - the compiler recognizes the patterns in the body.)

Examples:

size_t array[2];

array[0] = 2;
array[1] = 0x100;

assert(bt(array.ptr, 1));
assert(array[0] == 2);
assert(array[1] == 0x100);

pure nothrow @nogc @system int btc(size_t* p, size_t bitnum);

Tests and complements the bit.

pure nothrow @nogc @system int btr(size_t* p, size_t bitnum);

Tests and resets (sets to 0) the bit.

pure nothrow @nogc @system int bts(size_t* p, size_t bitnum);

Tests and sets the bit.

Parameters:

size_t* p	a non-NULL pointer to an array of size_ts.
size_t bitnum	a bit number, starting with bit 0 of p[0], and progressing. It addresses bits like the expression: p[index / (size_t.sizeof*8)] & (1 << (index & ((size_t.sizeof*8) - 1)))

Returns:

A non-zero value if the bit was set, and a zero if it was clear.

Examples:

size_t array[2];

array[0] = 2;
array[1] = 0x100;

assert(btc(array.ptr, 35) == 0);
if (size_t.sizeof == 8)
{
    assert(array[0] == 0x8_0000_0002);
    assert(array[1] == 0x100);
}
else
{
    assert(array[0] == 2);
    assert(array[1] == 0x108);
}

assert(btc(array.ptr, 35));
assert(array[0] == 2);
assert(array[1] == 0x100);

assert(bts(array.ptr, 35) == 0);
if (size_t.sizeof == 8)
{
    assert(array[0] == 0x8_0000_0002);
    assert(array[1] == 0x100);
}
else
{
    assert(array[0] == 2);
    assert(array[1] == 0x108);
}

assert(btr(array.ptr, 35));
assert(array[0] == 2);
assert(array[1] == 0x100);

pure nothrow @nogc @safe uint bswap(uint v);

Swaps bytes in a 4 byte uint end-to-end, i.e. byte 0 becomes byte 3, byte 1 becomes byte 2, byte 2 becomes byte 1, byte 3 becomes byte 0.

nothrow @nogc @system ubyte inp(uint port_address);

nothrow @nogc @system ushort inpw(uint port_address);

nothrow @nogc @system uint inpl(uint port_address);

Reads I/O port at port_address.

nothrow @nogc @system ubyte outp(uint port_address, ubyte value);

nothrow @nogc @system ushort outpw(uint port_address, ushort value);

nothrow @nogc @system uint outpl(uint port_address, uint value);

Writes and returns value to I/O port at port_address.

pure nothrow @nogc @safe int popcnt(uint x);

Calculates the number of set bits in a 32-bit integer.

pure nothrow @nogc @trusted uint bitswap(uint x);

Reverses the order of bits in a 32-bit integer.