Code for my second blog post on CTFE in D 2/0

gistfile1.d

module rotationmatrices;

import std.stdio;
import cordicalgorithm;

struct mat(T = float){
  T[][] data;
  
  pure mat!T opBinary(string op)(mat!T rhs){
    static if (op == "*" || op == "+" || op == "-"){
      return mat!T(mmOp!(T, op)(data, rhs.data));
    }else static assert(0, "Operator "~op~" not implemented"); 
  }

  pure bool opEquals(ref const mat!T rhs){
    equals_t tmp = true;
    foreach(i; 0..data.length){
      foreach(j; 0..data.length){
        if(!tmp) return tmp;
        tmp = tmp && (data[i][j] == rhs.data[i][j]);
      }
    }
    return tmp;
  }
}


pure T[][] mmOp(T = float, string op)(in T[][] A, in T[][] B)
in{
  assert(isFloatingPoint!T, "T must be a FloatingPoint type"); 
  assert(A.length > 0,"A has no length");
  assert(B.length > 0,"B has no length");
  foreach(i; 0 .. A.length){
    assert(A[i].length == B.length, "A[i].length != B.length");
  }
}
body{
  T[][] d;
  T tmp;
  foreach(i; 0 .. A.length){
    T[] row;
    foreach(j; 0 .. B[i].length){ 
      tmp = 0.0;
      foreach(k; 0 .. A[i].length){ 
        tmp += mixin("A[i][k] "~op~" B[k][j]");
      }
      row ~= tmp;
    }
    d ~= row;
  }
  return d;
}

pure mat!(T)[3][] gen_rotationmatrices(T = float)(){
  mat!(T)[3][] result = new mat!(T)[3][](360);
  T sini,cosi;
  debug pragma(msg, "Generating rotation matrices");
  foreach(i; 0 .. 360){ 
    sini = sin(i);
    cosi = cos(i);
    result[i] = [
     mat!(T)([[ 1.0,   0.0,  0.0], [ 0.0, cosi, -sini], [  0.0, sini, cosi]]),
     mat!(T)([[cosi,   0.0, sini], [ 0.0,  1.0,   0.0], [-sini,  0.0, cosi]]),
     mat!(T)([[cosi, -sini,  0.0], [sini, cosi,   0.0], [  0.0,  0.0,  1.0]])];
  }
  debug pragma(msg, "Done rotation matrices");
  return result;
}


immutable rmatrix = gen_rotationmatrices!double();
enum{YAW = 0, PITCH = 1, ROLL = 2};

pure auto yaw(size_t deg){   deg = degreeloop(deg); return cast(matrix)rmatrix[deg][YAW];  }
pure auto pitch(size_t deg){ deg = degreeloop(deg); return cast(matrix)rmatrix[deg][PITCH];}
pure auto roll(size_t deg){  deg = degreeloop(deg); return cast(matrix)rmatrix[deg][ROLL]; }

pure auto rotationmatrix(size_t y,size_t p,size_t r,){
  return yaw(y) * pitch(p) * roll(r);
}