1// Copyright (C) 2011 The Android Open Source Project
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//      http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#pragma version(1)
16#pragma rs java_package_name(com.example.android.rs.computeperf)
17
18const int gMaxIteration = 500;
19const int gDimX = 1024;
20const int gDimY = 1024;
21
22void root(uchar4 *v_out, uint32_t x, uint32_t y) {
23    float2 p;
24    p.x = -2.5f + ((float)x / gDimX) * 3.5f;
25    p.y = -1.f + ((float)y / gDimY) * 2.f;
26
27    float2 t = 0;
28    float2 t2 = t * t;
29    int iteration = 0;
30    while((t2.x + t2.y < 4.f) && (iteration < gMaxIteration)) {
31        float xtemp = t2.x - t2.y + p.x;
32        t.y = 2 * t.x * t.y + p.y;
33        t.x = xtemp;
34        iteration++;
35        t2 = t * t;
36    }
37
38    if(iteration >= gMaxIteration) {
39        *v_out = 0;
40    } else {
41        *v_out = (uchar4){iteration & 0xff, (iteration >> 6) & 0xff, 0x8f, 0xff};
42    }
43}
44