int d = y * 256 - h * 128 + lineHeight * 128; //256 and 128 factors to avoid floats
          int texY = ((d * texHeight) / lineHeight) / 256;
          int color = texture[texNum][texWidth * texY + texX];
          //make color darker for y-sides: R, G and B byte each divided through two with a "shift" and an "and"
          if(side == 1) color = (color >> 1) & 8355711;
          buffer[x][y] = color;

currentDist = h / (2.0 * y - h); //you could make a small lookup table for this instead

   double weight = (currentDist - distPlayer) / (distWall - distPlayer);

   double currentFloorX = weight * floorXWall + (1.0 - weight) * posX;
   double currentFloorY = weight * floorYWall + (1.0 - weight) * posY;

   int floorTexX, floorTexY;
   floorTexX = int(currentFloorX * texWidth) % texWidth;
   floorTexY = int(currentFloorY * texHeight) % texHeight;

   //floor
   buffer[x][y] = (texture[3][texWidth * floorTexY + floorTexX] >> 1) & 8355711;
   //ceiling (symmetrical!)
   buffer[x][h - y] = texture[6][texWidth * floorTexY + floorTexX];

int d = y * 256 - h * 128 + lineHeight * 128; //256 and 128 factors to avoid floats  
           int texY = ((d * texHeight) / lineHeight) / 256;  
           int color = texture[texNum][texWidth * texY + texX];  
           //make color darker for y-sides: R, G and B byte each divided through two with a "shift" and an "and"  
           if(side == 1) color = (color >> 1) & 8355711;  
           buffer[x][y] = color;

int d = y << 128 - h << 64 + lineHeight << 64; //256 and 128 factors to avoid floats  
           int texY = ((d << (texHeight >> 1)) >> (lineHeight >> 1)) >> 128;  
           int color = texture[texNum][texWidth << (texY >> 1) + texX];  
           //make color darker for y-sides: R, G and B byte each divided through two with a "shift" and an "and"  
           if(side == 1) color = (color >> 1) & 8355711;  
           buffer[x][y] = color;

int d = y << 8 - h << 7 + lineHeight << 7;

int texY = ((d << (texHeight >> 1)) >> (lineHeight >> 1)) >> 128;
int color = texture[texNum][texWidth << (texY >> 1) + texX];   

int texY = ((d * texHeight) / lineHeight) >> 8;
int color = texture[texNum][texWidth * texY + texX];

    int d1=lineHeight * 128;
       int d2=h * 128;
       for(int y = drawStart; y < drawEnd; y++)
       {
        int d = y *256 - d2 + d1;  //256 and 128 factors to avoid floats
        int texY = ((d * texHeight) / lineHeight) >>8;
         Uint32 color =texture[texNum][texWidth * texY + texX];
         if(side == 1) color = (color >> 1) & 8355711;
         buffer[x][y] = color;
             }

d1 = lineHeight * 128 + h * 128