Differences

This shows you the differences between two versions of the page.

--- std:bit [2023/04/08 16:17] – created rajit
+++ std:bit [2025/09/16 14:32] (current) – rajit
@@ Line 1: / Line 1: @@
-====== Bit-manipulation Functions ======
+====== Namespace std::bit  ======
+This namespace contains bit-manipulation functions that can make the ACT description more legible.
+<code act>
+export template<pint N, W> function repeat(int<W> x) : int<N*W>;
+</code>
+This concatenates ''N'' copies of the ''W''-bit input ''x'' to create an output of width ''N*W''.
+<code act>
+export template<pint W, W2> function sign_extend(int<W> x) : int<W2>;
+</code>
+This sign-extends the integer ''x'' (bitwidth ''W'') to bitwidth ''W2''. ''W2'' must be strictly larger than ''W''.
+<code act>
+export template<pint W> function rol(int<W> x) : int<W>;
+</code>
+Left rotate the ''W'' bit integer by 1. The MSB of ''x'' becomes the LSB of the result (rotating shift).
+<code act>
+export template<pint W> function ror(int<W> x) : int<W>;
+</code>
+Right rotate ''x'' by one, with the LSB of ''x'' becoming the MSB of the result.
+<code act>
+export template<pint W>  function find_msb_pos(int<W> x) : int<std::ceil_log2(W)>;
+</code>
+This function assumes that ''x'' is non-zero, and returns the bit position of the most significant one in ''x''.
+<code act>
+export template<pint W> function popcount(int<W> x) : int<std::ceil_log2(W+1)>;
+</code>
+This function returns a count of the number of bits of ''x'' that are set to 1.