A mask defines which bits you want to keep, and which bits you want to clear. Masking is the act of applying a mask to a value. This is accomplished by doing: Bitwise ANDing in order to extract a subset of the bits in the value Bitwise ORing in order to set a subset of … Read more
It’s quite simple actually. First a bit of code to demonstrate how it can be implemented. If you don’t understand anything about what this code is doing or how it works, feel free to ask additional questions in the comments: const FLAG_1 = 0b0001; // 1 const FLAG_2 = 0b0010; // 2 const FLAG_3 = … Read more
Fastest way? I’d use something like this: template <class T> constexpr T make_mask(std::size_t pos, std::size_t len) { return ((static_cast<T>(1) << len)-1) << pos; }
Briefly, a bitmask helps to manipulate the position of multiple values. There is a good example here; Bitflags are a method of storing multiple values, which are not mutually exclusive, in one variable. You’ve probably seen them before. Each flag is a bit position which can be set on or off. You then have a … Read more
Splendid question! Firstly, let’s make some assumptions about “better”. I’m assuming you don’t much care about disk space – a bitmask is efficient from a space point of view, but I’m not sure that matters much if you’re using SQL server. I’m assuming you do care about speed. A bitmask can be very fast when … Read more
I see values from at least a handful of different enumerations in there… My first thought was to approach the problem by splitting the permissions up in logical groups (RuleGroupPermissions, RulePermissions, LocationPermissions, …), and then having a class (WebAgentPermissions) exposing a property for each permission enum type. Since the permission values seem repetitive, you could … Read more
To “broadcast” the 32 bits of a 32-bit integer x to 32 bytes of a 256-bit YMM register z or 16 bytes of a two 128-bit XMM registers z_low and z_high you can do the following. With AVX2: __m256i y = _mm256_set1_epi32(x); __m256i z = _mm256_shuffle_epi8(y,mask1); z = _mm256_and_si256(z,mask2); Without AVX2 it’s best to do … Read more
Bit fields are a very handy and efficient tool for dealing with flags or any set of boolean values in general. To understand them you first need to know how binary numbers work. After that you should check out the manual entries on bitwise operators and make sure you know how a bitwise AND, OR … Read more
In general: value = (value & ~mask) | (newvalue & mask); mask is a value with all bits to be changed (and only them) set to 1 – it would be 0xf in your case. newvalue is a value that contains the new state of those bits – all other bits are essentially ignored. This … Read more
Most Raycast questions I see use the Layermask incorrectly. Although it works for them by luck but they usually run into issues when they actually want to exclude a GameObject from Raycast. This answer is made to cover all those scenarios that a person would want to use the Layer to filter GameObjects when performing … Read more