Function mulWrap [src]

rma = a * b with 2s-complement wrapping semantics. rma may 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. limbs_buffer is used for temporary storage. The amount required is given by calcMulWrapLimbsBufferLen.

Prototype

 pub fn mulWrap( rma: *Mutable, a: Const, b: Const, signedness: Signedness, bit_count: usize, limbs_buffer: []Limb, allocator: ?Allocator, ) void

Parameters

rma: *Mutablea: Constb: Constsignedness: Signednessbit_count: usizelimbs_buffer: []Limballocator: ?Allocator

Source

  pub fn mulWrap(
    rma: *Mutable,
    a: Const,
    b: Const,
    signedness: Signedness,
    bit_count: usize,
    limbs_buffer: []Limb,
    allocator: ?Allocator,
) void {
    var buf_index: usize = 0;
    const req_limbs = calcTwosCompLimbCount(bit_count);

    const a_copy = if (rma.limbs.ptr == a.limbs.ptr) blk: {
        const start = buf_index;
        const a_len = @min(req_limbs, a.limbs.len);
        @memcpy(limbs_buffer[buf_index..][0..a_len], a.limbs[0..a_len]);
        buf_index += a_len;
        break :blk a.toMutable(limbs_buffer[start..buf_index]).toConst();
    } else a;

    const b_copy = if (rma.limbs.ptr == b.limbs.ptr) blk: {
        const start = buf_index;
        const b_len = @min(req_limbs, b.limbs.len);
        @memcpy(limbs_buffer[buf_index..][0..b_len], b.limbs[0..b_len]);
        buf_index += b_len;
        break :blk a.toMutable(limbs_buffer[start..buf_index]).toConst();
    } else b;

    return rma.mulWrapNoAlias(a_copy, b_copy, signedness, bit_count, allocator);
}  