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99 lines
2.5 KiB
C++
99 lines
2.5 KiB
C++
#ifndef LEANSDR_MATH_H
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#define LEANSDR_MATH_H
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#include <math.h>
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#include <stdint.h>
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namespace leansdr {
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template<typename T>
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struct complex {
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T re, im;
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complex() : re(0), im(0) { }
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complex(T x) : re(x), im(0) { }
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complex(T x, T y) : re(x), im(y) { }
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inline void operator +=(const complex<T> &x) { re+=x.re; im+=x.im; }
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};
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template<typename T>
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complex<T> operator +(const complex<T> &a, const complex<T> &b) {
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return complex<T>(a.re+b.re, a.im+b.im);
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}
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template<typename T>
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complex<T> operator *(const complex<T> &a, const complex<T> &b) {
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return complex<T>(a.re*b.re-a.im*b.im, a.re*b.im+a.im*b.re);
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}
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template<typename T>
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complex<T> operator *(const complex<T> &a, const T &k) {
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return complex<T>(a.re*k, a.im*k);
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}
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template<typename T>
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complex<T> operator *(const T &k, const complex<T> &a) {
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return complex<T>(k*a.re, k*a.im);
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}
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// TBD Optimize with dedicated instructions
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inline int hamming_weight(uint8_t x) {
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static const int lut[16] = { 0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4 };
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return lut[x&15] + lut[x>>4];
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}
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inline int hamming_weight(uint16_t x) {
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return hamming_weight((uint8_t)x)
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+ hamming_weight((uint8_t)(x>>8));
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}
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inline int hamming_weight(uint32_t x) {
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return hamming_weight((uint16_t)x)
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+ hamming_weight((uint16_t)(x>>16));
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}
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inline int hamming_weight(uint64_t x) {
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return hamming_weight((uint32_t)x)
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+ hamming_weight((uint32_t)(x>>32));
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}
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inline unsigned char parity(uint8_t x) {
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x ^= x>>4;
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return (0x6996 >> (x&15)) & 1; // 16-entry look-up table
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}
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inline unsigned char parity(uint16_t x) {
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return parity((uint8_t)(x^(x>>8)));
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}
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inline unsigned char parity(uint32_t x) {
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return parity((uint16_t)(x^(x>>16)));
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}
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inline unsigned char parity(uint64_t x) {
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return parity((uint32_t)(x^(x>>32)));
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}
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inline int log2i(uint64_t x) {
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int n = -1;
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for ( ; x; ++n,x>>=1 ) ;
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return n;
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}
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// Pre-computed sin/cos for 16-bit angles
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struct trig16 {
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complex<float> lut[65536]; // TBD static and shared
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trig16() {
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for ( int a=0; a<65536; ++a ) {
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float af = a * 2*M_PI / 65536;
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lut[a].re = cosf(af);
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lut[a].im = sinf(af);
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}
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}
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inline const complex<float> &expi(uint16_t a) const {
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return lut[a];
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}
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// a must fit in a int32_t, otherwise behaviour is undefined
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inline const complex<float> &expi(float a) const {
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return expi((uint16_t)(int16_t)(int32_t)a);
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}
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};
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} // namespace
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#endif // LEANSDR_MATH_H
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