src/gallium/auxiliary/draw/draw_pt_elts.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  21  * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
  22  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  **************************************************************************/
  27
  28  /*
  29   * Authors:
  30   *   Keith Whitwell <keith@tungstengraphics.com>
  31   */
  32
  33 #include "draw/draw_pt.h"
  34 #include "draw/draw_private.h"
  35
  36 /* Neat get_elt func that also works for varrays drawing by encoding
  37  * the start value into a pointer.
  38  */
  39
  40 static unsigned elt_uint( const void *elts, unsigned idx )
  41 {
  42    return *(((const uint *)elts) + idx);
  43 }
  44
  45 static unsigned elt_ushort( const void *elts, unsigned idx )
  46 {
  47    return *(((const ushort *)elts) + idx);
  48 }
  49
  50 static unsigned elt_ubyte( const void *elts, unsigned idx )
  51 {
  52    return *(((const ubyte *)elts) + idx);
  53 }
  54
  55 static unsigned elt_vert( const void *elts, unsigned idx )
  56 {
  57    /* unsigned index is packed in the pointer */
  58    return (unsigned)(uintptr_t)elts + idx;
  59 }
  60
  61 pt_elt_func draw_pt_elt_func( struct draw_context *draw )
  62 {
  63    switch (draw->pt.user.eltSize) {
  64    case 0: return &elt_vert;
  65    case 1: return &elt_ubyte;
  66    case 2: return &elt_ushort;
  67    case 4: return &elt_uint;
  68    default: return NULL;
  69    }
  70 }
  71
  72 const void *draw_pt_elt_ptr( struct draw_context *draw,
  73                              unsigned start )
  74 {
  75    const char *elts = draw->pt.user.elts;
  76
  77    switch (draw->pt.user.eltSize) {
  78    case 0:
  79       return (const void *)(((const ubyte *)NULL) + start);
  80    case 1:
  81       return (const void *)(((const ubyte *)elts) + start);
  82    case 2:
  83       return (const void *)(((const ushort *)elts) + start);
  84    case 4:
  85       return (const void *)(((const uint *)elts) + start);
  86    default:
  87       return NULL;
  88    }
  89 }