The standard way to do division is by implementing binary long-division. This involves subtraction, so as long as you don’t discount this as not a bit-wise operation, then this is what you should do. (Note that you can of course implement subtraction, very tediously, using bitwise logical operations.) In essence, if you’re doing Q = … Read more
Some 2+ years after I asked this question I’d like to explain it the way I’d want it explained back when I was still a complete newb and would be most beneficial to people who want to understand the process. First of all, forget the “11111111” example value, which is not really all that suited … Read more
TMS320C28x DSP from Texas Instruments has a byte with 16 bits. Documentation for the compiler specifies CHAR_BIT as 16 on page 101. This appears to be a modern processor (currently being sold), compilers supporting C99 and C++03.
No, it will not be fully-portable. Packing options for structs are extensions, and are themselves not fully portable. In addition to that, C99 ยง6.7.2.1, paragraph 10 says: “The order of allocation of bit-fields within a unit (high-order to low-order or low-order to high-order) is implementation-defined.” Even a single compiler might lay the bit field out … Read more
In C, the language itself does not determine the representation of certain datatypes. It can vary from machine to machine, on embedded systems the int can be 16 bit wide, though usually it is 32 bit. The only requirement is that short int <= int <= long int by size. Also, there is a recommendation … Read more
Editor’s note: this is not actually what compilers do, and gives the wrong answer for large positive integers ending with 9, starting with div10(1073741829) = 107374183 not 107374182. It is exact for smaller inputs, though, which may be sufficient for some uses. Compilers (including MSVC) do use fixed-point multiplicative inverses for constant divisors, but they … Read more