Function mulWrapNoAlias [src]

rma = a * b with 2s-complement wrapping semantics. rma may not alias with a or b. a and b may alias with each other. Asserts the result fits in rma. An upper bound on the number of limbs needed by rma is given by a.limbs.len + b.limbs.len. If allocator is provided, it will be used for temporary storage to improve multiplication performance. error.OutOfMemory is handled with a fallback algorithm.

Prototype

 pub fn mulWrapNoAlias( rma: *Mutable, a: Const, b: Const, signedness: Signedness, bit_count: usize, allocator: ?Allocator, ) void

Parameters

rma: *Mutablea: Constb: Constsignedness: Signednessbit_count: usizeallocator: ?Allocator

Source

  pub fn mulWrapNoAlias(
    rma: *Mutable,
    a: Const,
    b: Const,
    signedness: Signedness,
    bit_count: usize,
    allocator: ?Allocator,
) void {
    assert(rma.limbs.ptr != a.limbs.ptr); // illegal aliasing
    assert(rma.limbs.ptr != b.limbs.ptr); // illegal aliasing

    const req_limbs = calcTwosCompLimbCount(bit_count);

    // We can ignore the upper bits here, those results will be discarded anyway.
    const a_limbs = a.limbs[0..@min(req_limbs, a.limbs.len)];
    const b_limbs = b.limbs[0..@min(req_limbs, b.limbs.len)];

    @memset(rma.limbs[0..req_limbs], 0);

    llmulacc(.add, allocator, rma.limbs, a_limbs, b_limbs);
    rma.normalize(@min(req_limbs, a.limbs.len + b.limbs.len));
    rma.positive = (a.positive == b.positive);
    rma.truncate(rma.toConst(), signedness, bit_count);
}  