Set/Unset Bits Operation

[O.B.]

I've written a small operation that sets/unsets bits within an
unsigned integer. Is there a better way to do this?

static uint setBits(uint original, uint newValue, uint offset, unint
mask)
{
return ((original >offset) & (~mask) | newValue) << offset;
}

Example:

uint test = 0xEC; // 1110 1100
uint TwoBitMask = 0x03;

uint offset = 3;

// Expect 1110 0100
uint result = setBits(test, 0, offset, TwoBitMask);

// Expect 1111 1100
result = setBits(test, 3, offset, TwoBitMask);

// Expect 1111 0100
result = setBits(test, 2, offset, TwoBitMask);

[O.B.]

Small bug in that last one (bits dropped when shifted). Let's try
that again:

static uint setBits(uint original, uint newValue, uint offset, uint
mask)
{
return original & ~(mask << offset) | (newValue << offset);
}

On Jul 6, 11:07 am, "O.B." <funkj...@bells outh.netwrote:

I've written a small operation that sets/unsets bits within an
unsigned integer. Is there a better way to do this?

static uint setBits(uint original, uint newValue, uint offset, unint
mask)
{
return ((original >offset) & (~mask) | newValue) << offset;

}

Example:

uint test = 0xEC; // 1110 1100
uint TwoBitMask = 0x03;

uint offset = 3;

// Expect 1110 0100
uint result = setBits(test, 0, offset, TwoBitMask);

// Expect 1111 1100
result = setBits(test, 3, offset, TwoBitMask);

// Expect 1111 0100
result = setBits(test, 2, offset, TwoBitMask);

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

O.B. wrote:

Small bug in that last one (bits dropped when shifted). Let's try
that again:

static uint setBits(uint original, uint newValue, uint offset, uint
mask)
{
return original & ~(mask << offset) | (newValue << offset);
}

I was just thinking when reading the first post that you should shift
the mask and the value instead of shifting the original. :)

--
Göran Andersson
_____
http://www.guffa.com