diff --git a/wavelet/wavelet2.hpp b/wavelet/wavelet2.hpp index e69de29..8fe0c88 100644 --- a/wavelet/wavelet2.hpp +++ b/wavelet/wavelet2.hpp @@ -0,0 +1,62 @@ +#pragma once + +#include "wavelet_constants.hpp" + +/* Rewrite of the basic functions + * This will make the adaption for the parallel case easier, + * because we can explicitly pass the two elements which are out of range + * (these are normally wrap-around values) + * + * These are also faster (testcase: size = 8, stride = 1, iterations = 100000) + * V2 0.00377901 + * V1 0.0345114 + * + * But also less abstract (which can be both a good thing and bad thing) + * + */ + +namespace wvlt{ + inline namespace V2 { + double inner_product(double* x, double const* coef, unsigned int stride){ + return x[0] * coef[0] + x[stride] * coef[1] + x[2*stride] * coef[2] + x[3*stride] * coef[3]; + } + + // will overwrite x, x1 and x2 are next elements, or wrap around + // size is size of vector x (so x[size-1] is valid) + void wavelet_mul(double* x, double x1, double x2, unsigned int size, unsigned int stride){ + assert(is_pow_of_two(size) && is_pow_of_two(stride) && 4*stride <= size); + + for(int i = 0; i < size - 2*stride; i += 2*stride){ + double y1 = inner_product(x + i, evn_coef, stride); + double y2 = inner_product(x + i, odd_coef, stride); + x[i] = y1; + x[i+stride] = y2; + } + + int i = size - 2*stride; + double y1 = x[i] * evn_coef[0] + x[i+stride] * evn_coef[1] + x1 * evn_coef[2] + x2 * evn_coef[3]; + double y2 = x[i] * odd_coef[0] + x[i+stride] * odd_coef[1] + x1 * odd_coef[2] + x2 * odd_coef[3]; + x[i] = y1; + x[i+stride] = y2; + } + + // will overwrite x, x2 and x1 are previous elements, or wrap around + // size is size of vector x (so x[size-1] is valid) + void wavelet_inv(double* x, double x1, double x2, unsigned int size, unsigned int stride){ + assert(is_pow_of_two(size) && is_pow_of_two(stride) && 4*stride <= size); + + for(int i = size - 2*stride; i >= 2*stride; i -= 2*stride){ + double y1 = inner_product(x + i - 2*stride, evn_coef_inv, stride); + double y2 = inner_product(x + i - 2*stride, odd_coef_inv, stride); + x[i] = y1; + x[i+stride] = y2; + } + + int i = 0; + double y1 = x2 * evn_coef_inv[0] + x1 * evn_coef_inv[1] + x[i] * evn_coef_inv[2] + x[i+stride] * evn_coef_inv[3]; + double y2 = x2 * odd_coef_inv[0] + x1 * odd_coef_inv[1] + x[i] * odd_coef_inv[2] + x[i+stride] * odd_coef_inv[3]; + x[i] = y1; + x[i+stride] = y2; + } + } +}