WriteCoordBitMP/ReadCoordBitMP in Garry's Mod Lua (for prediction fixing!!!)

coordbitmp.lua

local function encodefloat(f, bIntegral, bLowPrecision)
    local signbit = (f <= -( bLowPrecision and COORD_RESOLUTION_LOWPRECISION or COORD_RESOLUTION ));
	local intval = math.floor(math.abs(f));
	local fractval = bLowPrecision and 
		( bit.band(math.floor(math.abs(f*COORD_DENOMINATOR_LOWPRECISION)), (COORD_DENOMINATOR_LOWPRECISION-1))) or
		( bit.band(math.floor(math.abs(f*COORD_DENOMINATOR)), (COORD_DENOMINATOR-1) ));

	local bInBounds = intval < (2 ^ COORD_INTEGER_BITS_MP );

	--[[ unsigned ]] local intvalret, fractvalret
    local INBOUNDS, INTVAL, SIGN

	if ( bIntegral ) then
		-- Integer encoding: in-bounds bit, nonzero bit, optional sign bit + integer value bits
		if (0 ~= intval) then
			-- Adjust the integers from [1..MAX_COORD_VALUE] to [0..MAX_COORD_VALUE-1]
		    intvalret = intval - 1;
            SIGN = signbit
            INBOUNDS = bInBounds
            INTVAL = true
		else
            INBOUNDS = bInBounds
		end
	else
		-- Float encoding: in-bounds bit, integer bit, sign bit, fraction value bits, optional integer value bits
		if (intval ~= 0) then
			-- Adjust the integers from [1..MAX_COORD_VALUE] to [0..MAX_COORD_VALUE-1]
			intvalret = intval - 1;
            SIGN = signbit
            INBOUNDS = bInBounds
            INTVAL = true
			fractvalret = fractval
		else
            SIGN = signbit
            INBOUNDS = bInBounds
            INTVAL = false
			fractvalret = fractval
		end
	end

	return INBOUNDS, INTVAL, SIGN, intvalret, fractvalret;
end

local mul_table =
{
    1/(2^COORD_FRACTIONAL_BITS),
    -1/(2^COORD_FRACTIONAL_BITS),
    1/(2^COORD_FRACTIONAL_BITS_MP_LOWPRECISION),
    -1/(2^COORD_FRACTIONAL_BITS_MP_LOWPRECISION)
};

local function decodefloat(bIntegral, bLowPrecision, INBOUNDS, INTVAL, SIGN, intvalret, fractvalret)
    -- BitCoordMP float encoding: inbounds bit, integer bit, sign bit, optional int bits, float bits
    -- BitCoordMP integer encoding: inbounds bit, integer bit, optional sign bit, optional int bits.
    -- int bits are always encoded as (value - 1) since zero is handled by the integer bit

    -- With integer-only encoding, the presence of the third bit depends on the second

    if ( bIntegral ) then
        if ( INTVAL ) then
            -- Read the third bit and the integer portion together at once
            -- Remap from [0,N] to [1,N+1]
            intval = math.floor(intvalret * 2^-1) + 1;
            return (intvalret % 2 == 1) and -intval or intval;
        end
        return 0;
    end
    local bits = fractvalret

    -- equivalent to: float multiply = mul_table[ ((flags & SIGN) ? 1 : 0) + bLowPrecision*2 ];
    --float multiply = *(float*)((uintptr_t)&mul_table[0] + (flags & 4) + bLowPrecision*8);
    local multiply = mul_table[(SIGN and 1 or 0) + (bLowPrecision and 1 or 0)*2 + 1]

    if ( INTVAL ) then
        -- Shuffle the bits to remap the integer portion from [0,N] to [1,N+1]
        -- and then paste in front of the fractional parts so we only need one
        -- int-to-float conversion.
        
        
    	local fracbits = fractvalret
        local intpart = intvalret
        local intbitsLow = intpart * 2 ^ COORD_FRACTIONAL_BITS_MP_LOWPRECISION;
        local intbits = intpart * 2 ^ COORD_FRACTIONAL_BITS;
        local selectNotLow = (bLowPrecision and 1 or 0) - 1;
        
        intbits = intbits - intbitsLow;
        intbits = bit.band(intbits, selectNotLow);
        intbits = intbits + intbitsLow;
        bits = bit.bor(fracbits, intbits);
    end

    return math.floor(bits) * multiply;
end

local function networkedfloatencode(f)
    return decodefloat(false, false, encodefloat(f, false, false))
end