Converting arm code to use NEON intrinsics -


i have been trying modify code beneath work neon intrinsics, thereby creating speedup. unfortunately nothing seems work correctly. have idea going wrong? updated doubles single floating point elements. 

typedef         float       real; typedef         real        vec3[3];      typedef struct  driehoek {     vec3        norm;                   /* face normal. */     real        d;                      /* plane equation d. */     vec3        *vptr;                  /* global vertex list pointer. */     vec3        *nptr;                  /* global normal list pointer. */     int         vindex[3];              /* index of vertices. */     int         indx;                   /* normal component max flag. */     bool        norminterp;             /* normal interpolation? */     bool        vorder;                 /* vertex order orientation. */ }driehoek;  typedef struct element {     int         index;     struct object   *parent;            /* ptr parent object.    */     char        *data;                  /* pointer data info.         */     bbox        bv;                     /* element bounding volume.      */ }element;  int triangleintersection(ray *pr, element *pe, irecord *hit) {     float      rd_dot_pn;       /* polygon normal dot ray direction. */     float      ro_dot_pn;       /* polygon normal dot ray origin.    */     float      q1, q2;     float      tval;            /* intersection t distance value.    */     vec3       *v1, *v2, *v3;       /* vertex list pointers.         */     vec3       e1, e2, e3;      /* edge vectors.             */     driehoek   *pt;         /* ptr triangle data.         */       pt = (driehoek *)pe->data;      rd_dot_pn = vecdot(pt->norm, pr->d);      if (abs(rd_dot_pn) < rayeps)        /* ray parallel.      */         return (0);          hit->b3 = e1[0] * (q2 - (*v1)[1]) - e1[1] * (q1 - (*v1)[0]);         if (!inside(hit->b3, pt->norm[2]))             return (0);         break;     }      return (1);  }

an array of float vec[3] not enough of hint compiler neon intrinsic can used. issue float vec[3] has each element individually addressable. compiler must store each in floating point register. see gcc neon intrinsic documentation.

although 3 dimensions common in universe, our friends computers binary. have 2 data types can used neon intrinsics; float32x4_t , float32x2_t. need use intrinsics such vfmaq_f32, vsubq_f32, etc. these intrinsics different each compiler; guess using gcc. should use intrinsic data types combining float32x2_t single float can result in movement between register types, expensive. if algorithm can treat each dimension separately, might able combine types. however, don't think have register pressure , simd speed-up should beneficial. keep in float32x4_t begin with. maybe able use dimension 3d-projection when comes rendering phase.

here source cmath library called math-neon under lgpl. instead of using intrinsics gcc, uses inline assembler.neon intrinsics vs assembly

see also: armcc neon intrinsics, if using arm compiler.


Comments

Post a Comment

Popular posts from this blog

jquery - How can I dynamically add a browser tab? -

since using iframes house external pages are, accounts "not preferred method" , disallowed sites (flickr, one), want dynamically generate browser tabs. e.g., when user submits form, want dynamically generate tab on browser in response submitted. e.g., might want add new tab url like: http://www.bigsurgarrapata.com/contact how in jquery? you want form target attribute action attribute. http://www.w3schools.com/tags/att_form_target.asp browsers have ultimate control on result of target attribute open new tab value of _blank. <form action="contact_submit.php" target="_blank" method="post">
Read more

node.js - Getting the socket id,user id pair of a logged in user(s) -

i have web application done using node js , in it,i have authentication system requires users log in before can access pages. have 2 pages,the homepage , updates page. from read docs,a new socket id issued when user opens tab in browser. me being admin,i know socket id of logged in user , more so,the socket id,logged in user id pair logged in users. what method can use socket id,logged in user id pair make sure broadcast realtime info users online?.
Read more

keyboard - C++ GetAsyncKeyState alternative -

i using windows.h library's getasynckeystate function define key pushed on keyboard . here program returns int value of pushed key example. #include <iostream> #include <windows.h> using namespace std; int main (){ char i; for(i=8;i<190;i++){ if(getasynckeystate(i)== -32767){ cout<<int (i)<<endl; } } return 0; } but trying make opengl simple game , function appeared slow . there function not need cycle 180 times , if statement . thanks you're trying make opengl game, you're going use glfw. if that's case can away using glfwgetkey() such: if (glfwgetkey(glfw_key_up) == glfw_press) {...} if (glfwgetkey(glfw_key_down) == glfw_press) {...} that method nicely explained in tutorial 6 opengl-tutorial.org . should start first tutorial of beginners tutorials , later intermediate tutorials . if you're going make win32 window can listen wm_keydown or wm_keyup messages , virtua
Read more