Zig 0.17.0-dev (Split by item)

?

× Shortcut keys

?: Show these tips

S: Focus search field

Esc: Clear focus & close tips

U: Jump to source code

↑: Move up in search results

↓: Move down in search results

↵: Go to active search result

This is an example of documentation generated by ZigDoc, an alternative to Zig's built-in Auto Doc feature. See also examples in other modes/formats. The project being documented here (as the example) is the Zig standard library. Public Function

pow

Doc Source

Public Function

std.math.big.int.Mutable.pow

pub fn pow(r: *Mutable, a: Const, b: u32, limbs_buffer: []Limb) void

q = a ^ b

r may not alias a.

Asserts that r has enough limbs to store the result. Upper bound is calcPowLimbsBufferLen(a.bitCountAbs(), b).

limbs_buffer is used for temporary storage. The amount required is given by calcPowLimbsBufferLen.

Params

r: *Mutable
a: Const
b: u32
limbs_buffer: []Limb

File

math/big/int.zig:1546

    pub fn pow(r: *Mutable, a: Const, b: u32, limbs_buffer: []Limb) void {
        assert(r.limbs.ptr != a.limbs.ptr); // illegal aliasing

        // Handle all the trivial cases first
        switch (b) {
            0 => {
                // a^0 = 1
                return r.set(1);
            },
            1 => {
                // a^1 = a
                return r.copy(a);
            },
            else => {},
        }

        if (a.eqlZero()) {
            // 0^b = 0
            return r.set(0);
        } else if (a.limbs.len == 1 and a.limbs[0] == 1) {
            // 1^b = 1 and -1^b = ±1
            r.set(1);
            r.positive = a.positive or (b & 1) == 0;
            return;
        }

        // Here a>1 and b>1
        const needed_limbs = calcPowLimbsBufferLen(a.bitCountAbs(), b);
        assert(r.limbs.len >= needed_limbs);
        assert(limbs_buffer.len >= needed_limbs);

        llpow(r.limbs, a.limbs, b, limbs_buffer);

        r.normalize(needed_limbs);
        r.positive = a.positive or (b & 1) == 0;
    }