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POTroubles introducing SIMD commands into the code
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copied!<p>I have a basic calculation function that I apply on each item in an array. This function does more then just summing two vectors.</p> <p>I wanted to work on multiple items from my array in parallel using SIMD commands.</p> <p>As I found these kind of examples too simple for my case (they don't include function calls): <a href="http://www.doc.ic.ac.uk/~nloriant/files/scfpsc-pc.pdf" rel="nofollow">http://www.doc.ic.ac.uk/~nloriant/files/scfpsc-pc.pdf</a></p> <p>I tried using array notation as in here: <a href="http://software.intel.com/sites/products/documentation/hpc/composerxe/en-us/cpp/mac/optaps/common/optaps_elem_functions.htm" rel="nofollow">http://software.intel.com/sites/products/documentation/hpc/composerxe/en-us/cpp/mac/optaps/common/optaps_elem_functions.htm</a></p> <p>But this did not accelerate my code. I don't understand what I am doing wrong and if I need to go to the more assembly-like style of SIMD, how do I introduce function calls there...</p> <p>If anyone can help me or refer me to a good source for my needs I'll be very thakful.</p> <p>Thank you!!!!</p> <hr> <p>code example:</p> <p>This is the basic function applied on each item in the array:</p> <pre><code>float VarFlow::gauss_seidel_step(IplImage* u, int i, float h, float J11, float J12, float J13, float vi){ int x = i%u->width; int y = i/u->width; int start_y, end_y, start_x, end_x; int N_num = 0; start_y = y - 1; end_y = y + 1; start_x = x - 1; end_x = x+1; float temp_u = 0; // Sum top neighbor if(start_y > -1){ temp_u += *((float*)(u->imageData + start_y*u->widthStep) + x); N_num++; } // Sum bottom neighbor if(end_y < u->height){ temp_u += *((float*)(u->imageData + end_y*u->widthStep) + x); N_num++; } // Sum left neighbor if(start_x > -1){ temp_u += *((float*)(u->imageData + y*u->widthStep) + start_x); N_num++; } // Sum right neighbor if(end_x < u->width){ temp_u += *((float*)(u->imageData + y*u->widthStep) + end_x); N_num++; } temp_u = temp_u - (h*h/alpha)*(J12*vi + J13); temp_u = temp_u / (N_num + (h*h/alpha)*J11); return temp_u; </code></pre> <p>}</p> <p>I'd like to declare it with __declspec (vector) and call it like so:</p> <pre><code> u_ptr[0:max_i:1] = gauss_seidel_step(imgU, vect[0:max_i:1], h, fxfx_ptr[0:max_i:1], fxfy_ptr[0:max_i:1], fxft_ptr[0:max_i:1], v_ptr[0:max_i:1]); v_ptr[0:max_i:1] = gauss_seidel_step(imgV, vect[0:max_i:1], h, fyfy_ptr[0:max_i:1], fxfy_ptr[0:max_i:1], fyft_ptr[0:max_i:1], u_ptr[0:max_i:1]); </code></pre> <p>Instead of a for loop.</p> <p>I'll be happy to get a direction with this (maybe a link to a similar example) but <strong>not</strong> a full solution.</p> <p>Thanks!</p>

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