Is there a way to specify unsigned integers in the OData Metadata (CSDL) format? I have a data structure that contains an unsigned 64 bit integer, but from the documentation here it seems there isn't a choice for unsigned integers?
What are my options? Use the string version of the 64 bit number, or use the Edm.Binary type to specify the hex representation? Is there a better way?
Related
On 64-bit RISC-V, when a 32-bit operand is loaded into a register, it is necessary to decide whether to sign-extend or zero-extend to 64 bits, and the architectural decision was made to prefer the former, presumably on the grounds that the most common int type in C family languages is a signed 32-bit integer. So sign extension is slightly faster than zero extension.
Is the same true of 8-bit operands? In other words, is signed char more efficient than unsigned char?
If you’re going to be widening a lot of 8-bit values to wchar_t, unsigned char is what you want, because that’s a no-op rather than a bitmask. If your char format is UTF-8, you also want to be able to use unsigned math for your shifts. If you’re using library functions, it’s most convenient to use the types your library expects.
The RISC-V architecture has both a LB instruction that loads a sign-extended 8-bit value into a register, and a LBU instruction that zero-extends. Both are equally efficient. In C, any signed char used in an arithmetic operation is widened to int, and the C standard library functions specify widening char to int, so this puts the variable in the correct format to use.
Storing is a matter of truncation, and converting from any integral type to unsigned char is trivial (bitmask by 0xff). Converting from an unsigned char to a signed value can be done in no more than two instructions, without conditionals or register pressure (SLLI to put the sign bit of the char into the sign bit of the machine register, followed by SRLI to sign-extend the upper bits).
There is therefore no additional overhead in this architecture to working with either. The API specifies sign-extension rather than zero-extension of signed quantities.
Incidentally, RV64I does not architecturally prefer sign-extension. That is the ABI convention, but the instruction set adds a LWU instruction to load a 32-bit value from memory with zero-extension and an ADDIW that can sign-extend a zero-extended 32-bit result. (There is no corresponding ADDIB for 8-bit or ADDIH for 16-bit quantities.)
I want to know when to use VARINT instead of BIGINT?
What is the limitation of each of them and how much space is being used by VARINT?
As per the documentation the bigint is a 64bit signed integer, whereas varint is an arbitrary precision integer, corresponding to the BigInteger type in java.
everyone! I'm trying to become familiar with TinyOS.
I'd like to know the difference between uint8_t and uint16_t.
Thank you in advance :-)
Just for the sake of thoroughness:
Data types come in many shapes and sizes. The two you are referring to are of types unsigned 8 bit integer and unsigned 16 bit integer.
An integer is a whole number that can be positive or negative; however, in the case of types an unsigned integer can only be positive as it does not designate space for a sign (i.e. a negative sign). 8 bit and 16 bit refer to the amount of space the integer takes up in memory. An unsigned 8 bit integer's values can be 0 - 255 while an unsigned 16 bit integer can hold values from 0 - 65,535 (Side note: If you are familiar with networking you may notice that 65,535 is the largest port number possible. This is due to the fact a port number is an unsigned 16 bit integer.)
Hope this helps.
In all of my time programming I have squeaked by without ever learning this stuff. Would love to know more about what these are and how they are used:
UInt8
UInt16LE
UInt16BE
UInt32LE
UInt32BE
Int8
Int16LE
Int16BE
Int32LE
Int32BE
FloatLE
FloatBE
DoubleLE
DoubleBE
See https://nodejs.org/api/buffer.html#buffer_buf_readuint8_offset_noassert for where Node uses these.
This datatypes are related to number representation in appropriate byte-order. It typically essential for:
Network protocols
Binary file formats
It is essential because one system should write integers/floats in such way that will give the same value on reader side. So what format to be used is just convention between two sides (writer and reader).
What acronyms means:
BE suffix stands for BigEndian
LE stands for LittleEndian
Int is Integer
Uint is Unsigned Integer
Appropriate number in integers is number of bits in the word.
I would like to represent a 10 bit unsigned integer in C#. I need to read and write it into BinaryStream and use ++ unary operator. Should I use int as an internal representation or is there a better way?
I would use unsigned short as my base type. Writing to binary stream is going to be fun no matter what, because you'll need to pack four of these numbers to get a whole number of bytes into the stream (assuming that you want packing).
Depending on what you want to do, using an UInt16 caped to 10 bit is a good solution. You will need to overload some operators but that should be it.
The other alternative would be to use a BitArray and to redifine the ++ unary operator.