FastLED 3.9.15
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◆ sin16_C()

LIB8STATIC int16_t sin16_C ( uint16_t theta)

Fast 16-bit approximation of sin(x).

This approximation never varies more than 0.69% from the floating point value you'd get by doing

float s = sin(x) * 32767.0;
int x
Definition simple.h:92
Parameters
thetainput angle from 0-65535
Returns
sin of theta, value between -32767 to 32767.

Definition at line 122 of file trig8.h.

122 {
123 static const uint16_t base[] = {0, 6393, 12539, 18204,
124 23170, 27245, 30273, 32137};
125 static const uint8_t slope[] = {49, 48, 44, 38, 31, 23, 14, 4};
126
127 uint16_t offset = (theta & 0x3FFF) >> 3; // 0..2047
128 if (theta & 0x4000)
129 offset = 2047 - offset;
130
131 uint8_t section = offset / 256; // 0..7
132 uint16_t b = base[section];
133 uint8_t m = slope[section];
134
135 uint8_t secoffset8 = (uint8_t)(offset) / 2;
136
137 uint16_t mx = m * secoffset8;
138 int16_t y = mx + b;
139
140 if (theta & 0x8000)
141 y = -y;
142
143 return y;
144}
int y
Definition simple.h:93
UISlider offset("Offset", 0.0f, 0.0f, 1.0f, 0.01f)

References LIB8STATIC, offset(), and y.

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