1 /*-------------------------------------------------------------------------
2  * drawElements Base Portability Library
3  * -------------------------------------
4  *
5  * Copyright 2015 The Android Open Source Project
6  *
7  * Licensed under the Apache License, Version 2.0 (the "License");
8  * you may not use this file except in compliance with the License.
9  * You may obtain a copy of the License at
10  *
11  *      http://www.apache.org/licenses/LICENSE-2.0
12  *
13  * Unless required by applicable law or agreed to in writing, software
14  * distributed under the License is distributed on an "AS IS" BASIS,
15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16  * See the License for the specific language governing permissions and
17  * limitations under the License.
18  *
19  *//*!
20  * \file
21  * \brief Testing of deMath functions.
22  *//*--------------------------------------------------------------------*/
23 
24 #include "deMath.h"
25 #include "deRandom.h"
26 
27 DE_BEGIN_EXTERN_C
28 
conversionToFloatLosesPrecision(deInt32 x)29 static deBool conversionToFloatLosesPrecision (deInt32 x)
30 {
31 	if (x == -0x7FFFFFFF - 1)
32 		return DE_FALSE;
33 	else if (x < 0)
34 		return conversionToFloatLosesPrecision(-x);
35 	else if (x == 0)
36 		return DE_FALSE;
37 	else if (((deUint32)x & 0x1) == 0)
38 		return conversionToFloatLosesPrecision(x >> 1); /* remove trailing zeros */
39 	else
40 		return x > ((1 << 24) - 1); /* remaining part does not fit in the mantissa? */
41 }
42 
testSingleInt32ToFloat(deInt32 x)43 static void testSingleInt32ToFloat (deInt32 x)
44 {
45 	/* roundTowardsToNegInf(x) <= round(x) <= roundTowardsPosInf(x). */
46 	/* \note: Need to use inequalities since round(x) returns arbitrary precision floats. */
47 	DE_TEST_ASSERT(deInt32ToFloatRoundToNegInf(x) <= deInt32ToFloat(x));
48 	DE_TEST_ASSERT(deInt32ToFloat(x) <= deInt32ToFloatRoundToPosInf(x));
49 
50 	/* if precision is lost, floor(x) < ceil(x). Else floor(x) == ceil(x) */
51 	if (conversionToFloatLosesPrecision(x))
52 		DE_TEST_ASSERT(deInt32ToFloatRoundToNegInf(x) < deInt32ToFloatRoundToPosInf(x));
53 	else
54 		DE_TEST_ASSERT(deInt32ToFloatRoundToNegInf(x) == deInt32ToFloatRoundToPosInf(x));
55 
56 	/* max one ulp from each other */
57 	if (deInt32ToFloatRoundToNegInf(x) < deInt32ToFloatRoundToPosInf(x))
58 	{
59 		union
60 		{
61 			float f;
62 			deInt32 u;
63 		} v0, v1;
64 
65 		v0.f = deInt32ToFloatRoundToNegInf(x);
66 		v1.f = deInt32ToFloatRoundToPosInf(x);
67 
68 		DE_TEST_ASSERT(v0.u + 1 == v1.u || v0.u == v1.u + 1);
69 	}
70 }
71 
testInt32ToFloat(void)72 static void testInt32ToFloat (void)
73 {
74 	const int	numIterations = 2500000;
75 
76 	int			sign;
77 	int			numBits;
78 	int			delta;
79 	int			ndx;
80 	deRandom	rnd;
81 
82 	deRandom_init(&rnd, 0xdeadbeefu-1);
83 
84 	for (sign = -1; sign < 1; ++sign)
85 	for (numBits = 0; numBits < 32; ++numBits)
86 	for (delta = -2; delta < 3; ++delta)
87 	{
88 		const deInt64 x = (deInt64)(sign == -1 ? (-1) : (+1)) * (1LL << (deInt64)numBits) + (deInt64)delta;
89 
90 		/* would overflow */
91 		if (x > 0x7FFFFFFF || x < -0x7FFFFFFF - 1)
92 			continue;
93 
94 		testSingleInt32ToFloat((deInt32)x);
95 	}
96 
97 	for (ndx = 0; ndx < numIterations; ++ndx)
98 		testSingleInt32ToFloat((deInt32)deRandom_getUint32(&rnd));
99 }
100 
deMath_selfTest(void)101 void deMath_selfTest (void)
102 {
103 	/* Test Int32ToFloat*(). */
104 	testInt32ToFloat();
105 }
106 
107 DE_END_EXTERN_C
108