#! /usr/bin/python

# Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).

#

# Permission is hereby granted, free of charge, to any person obtaining a

# copy of this software and /or associated documentation files

# (the "Materials "), to deal in the Materials without restriction,

# including without limitation the rights to use, copy, modify, merge,

# publish, distribute, sublicense, and/or sell copies of the Materials,

# and to permit persons to whom the Materials are furnished to do so,

# subject to the following conditions:

#

# The above copyright notice and this permission notice shall be included

# in all copies or substantial portions of the Materials.

#

# THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,

# DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR

# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE MATERIALS OR

# THE USE OR OTHER DEALINGS IN THE MATERIALS.

from c_utils import *

# \todo Might require a more accurate table for lookups.

RCP_BITS = 8

RCP_DATATYPE_BITS = RCP_BITS + 8

def tofx(f):

    return int(f * (1<<RCP_BITS) + 0.5)

def alpha_to_uintrcp(alpha):

    if alpha == 0:

        rf = 255 # Max out

    else:

        rf = 255.0/alpha

    i = tofx(rf)

    assert(i < (1<<RCP_DATATYPE_BITS))

    return i

def test_error():

    max_err = 0

    for alpha in range(1, 256):

        for color in range(0, 256):

            if color > alpha:

                # Undefined result -> ignore test.

                continue

            fa = alpha / 255.0

            fc = color / 255.0

            ex = fc / fa

            exi = int(ex * 255.0 + 0.5)

            ia = alpha_to_uintrcp(alpha)

            m = (ia * color) >> RCP_BITS

            e = abs(exi - m)

            if e > max_err:

                print ia * color

                print alpha, color, exi, m, fa, fc, ex, ia / float(1<<RCP_BITS), ia

                max_err = e

    print max_err

    return max_err

if __name__ == '__main__':

    vals = []

    for alpha in range(0, 256):

       i = alpha_to_uintrcp(alpha)

       vals += [i]

    begin_include_guard("_SFALPHARCP_H_") 

    print ""

    make_include("riDefs.h")

    print ""

    begin_namespace("OpenVGRI")

    make_constant("ALPHA_RCP_BITS", RCP_BITS)

    make_array("static const", "RIuint16", "sc_alphaRcp", vals, hex_formatter)

    end_namespace()

    end_include_guard()