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diff --git a/README.md b/README.md new file mode 100644 index 0000000..3b99bcd --- /dev/null +++ b/README.md @@ -0,0 +1,40 @@ +# binary + +This is a liblet (a very small library consisting of one header file and +one source file) for working with binary numbers in C. + +The header file, `binary.h`, defines two macros for external use, `BIN` and +`BINSTRLEN`. It also declares one function which is defined in the source +file `binary.c`. Additional macros in `binary.h` which begin with `BIN_` +are implementation details and should not be considered part of the defined +interface. + +## BIN + +The macro `BIN` converts a binary literal number to a `uintmax_t`. For example: + + uintmax_t n = BIN(1010); + +This will result in the variable `n` having the value `0xa` (the hex +representation of the binary literal `1010`). + +## BINSTRLEN + +The symbolic constant `BINSTRLEN` defines the length of a `uintmax_t` +represented as a string of characters. Its primary use is for declaring an +array large enough to hold the results of `binstr()` (see below): + + char s[BINSTRLEN]; + +## binstr() + + char *binstr(size_t n, char s[n], uintmax_t b); + +This function converts the number `b` to its string representation in base 2. +The least significant `n - 1` bits are stored in the array `s`. The string +will be null terminated. + +## See Also + +There is no inverse function of `binstr()` provided, as this can be fulfilled +by calling `strtoumax()` with the third paramater (`base`) set to `2`. |