1/*
2 * Copyright (C) 2004-2010 NXP Software
3 * Copyright (C) 2010 The Android Open Source Project
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18#include "LVM_Types.h"
19#include "LVM_Macros.h"
20#include "ScalarArithmetic.h"
21
22/*-------------------------------------------------------------------------*/
23/* FUNCTION:                                                               */
24/*   LVM_Polynomial                                                        */
25/*                                                                         */
26/* DESCRIPTION:                                                            */
27/*   This function performs polynomial expansion                           */
28/*  Y = (A0 + A1*X + A2*X2 + A3*X3 + �.. + AN*xN) << AN+1                  */
29/*                                                                         */
30/*  LVM_INT32 LVM_Polynomial(LVM_UINT16    N,                              */
31/*                           LVM_INT32    *pCoefficients,                  */
32/*                           LVM_INT32    X)                               */
33/*                                                                         */
34/* PARAMETERS:                                                             */
35/*                                                                         */
36/*  N                is the polynomial order                               */
37/*  pCoefficients    is the ptr to polynomial coefficients A0,A1.. in Q.31 */
38/*  X                is the input variable                                 */
39/*                                                                         */
40/* RETURNS:                                                                */
41/*   The result of the polynomial expansion in Q1.31 format                */
42/*-------------------------------------------------------------------------*/
43
44LVM_INT32 LVM_Polynomial(LVM_UINT16    N,
45                         LVM_INT32    *pCoefficients,
46                         LVM_INT32    X)
47{
48    LVM_INT32 i;
49    LVM_INT32 Y,A,XTemp,Temp,sign;
50
51    Y=*pCoefficients; /* Y=A0*/
52    pCoefficients++;
53
54    if((LVM_UINT32)X==0x80000000)
55    {
56        Temp=-1;
57        sign=Temp;
58        for(i=1;i<=N;i++)
59        {
60            Y+=((*pCoefficients)*sign);
61            pCoefficients++;
62            sign*=Temp;
63        }
64
65
66    }
67    else
68    {
69        XTemp=X;
70        for(i=N-1;i>=0;i--)
71        {
72            A=*pCoefficients;
73            pCoefficients++;
74
75            MUL32x32INTO32(A,XTemp,Temp,31)
76            Y+=Temp;
77
78            MUL32x32INTO32(XTemp,X,Temp,31)
79            XTemp=Temp;
80        }
81    }
82    A=*pCoefficients;
83    pCoefficients++;
84
85    if(A<0)
86    {
87        A=Abs_32(A);
88        Y=Y>>A;
89    }
90    else
91    {
92        Y = Y<<A;
93    }
94    return Y;
95}
96
97