1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
|
#include <cmath>
#include <format>
#include <MathLogger.h>
#ifdef TUTORIAL_USE_SSE2
# include <emmintrin.h>
#endif
namespace {
mathlogger::Logger Logger;
#if defined(TUTORIAL_USE_GNU_BUILTIN)
typedef double v2df __attribute__((vector_size(16)));
double gnu_mysqrt(double x)
{
v2df root = __builtin_ia32_sqrtsd(v2df{ x, 0.0 });
double result = root[0];
Logger.Log(std::format("Computed sqrt of {} to be {} with GNU-builtins\n", x,
result));
return result;
}
#elif defined(TUTORIAL_USE_SSE2)
double sse2_mysqrt(double x)
{
__m128d root = _mm_sqrt_sd(_mm_setzero_pd(), _mm_set_sd(x));
double result = _mm_cvtsd_f64(root);
Logger.Log(
std::format("Computed sqrt of {} to be {} with SSE2\n", x, result));
return result;
}
#endif
// a hack square root calculation using simple operations
double fallback_mysqrt(double x)
{
if (x <= 0) {
return 0;
}
double result = x;
// do ten iterations
for (int i = 0; i < 10; ++i) {
if (result <= 0) {
result = 0.1;
}
double delta = x - (result * result);
result = result + 0.5 * delta / result;
Logger.Log(std::format("Computing sqrt of {} to be {}\n", x, result));
}
return result;
}
#include <SqrtTable.h>
double table_sqrt(double x)
{
double result = sqrtTable[static_cast<int>(x)];
// do ten iterations
for (int i = 0; i < 10; ++i) {
if (result <= 0) {
result = 0.1;
}
double delta = x - (result * result);
result = result + 0.5 * delta / result;
}
Logger.Log(
std::format("Computed sqrt of {} to be {} with TableSqrt\n", x, result));
return result;
}
double mysqrt(double x)
{
if (x >= 1 && x < 10) {
return table_sqrt(x);
}
#if defined(TUTORIAL_USE_GNU_BUILTIN)
return gnu_mysqrt(x);
#elif defined(TUTORIAL_USE_SSE2)
return sse2_mysqrt(x);
#else
return fallback_mysqrt(x);
#endif
}
}
namespace mathfunctions {
double sqrt(double x)
{
#ifdef TUTORIAL_USE_STD_SQRT
return std::sqrt(x);
#else
return mysqrt(x);
#endif
}
}
|
