sys/dev/rasops/rasops_masks.h

   1 /*      $NetBSD: rasops_masks.h,v 1.6 2001/01/12 23:03:52 bjh21 Exp $   */
   2
   3 /*-
   4  * Copyright (c) 1999 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Andrew Doran.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #ifndef _RASOPS_MASKS_H_
  33 #define _RASOPS_MASKS_H_ 1
  34
  35 #include <sys/types.h>
  36 #include <machine/endian.h>
  37
  38 /*
  39  * Convenience macros. To get around the problem of dealing with properly
  40  * ordered bits on little-endian machines, we just convert everything to
  41  * big-endian and back again when we're done.
  42  *
  43  * MBL: move bits left
  44  * MBR: move bits right
  45  * MBE: make big-endian
  46  */
  47 #if BYTE_ORDER == BIG_ENDIAN
  48
  49 #define MBL(x,y)        ((y) > 31 ? 0 : (x) >> (y))
  50 #define MBR(x,y)        ((y) > 31 ? 0 : (x) << (y))
  51 #define MBE(x)          (x)
  52
  53 #else
  54
  55 #define MBL(x,y)        ((y) > 31 ? 0 : MBE(MBE(x) << (y)))
  56 #define MBR(x,y)        ((y) > 31 ? 0 : MBE(MBE(x) >> (y)))
  57 #define MBE(x)          ( (((x) & 0x000000FFU) << 24) \
  58                         | (((x) & 0x0000FF00U) <<  8) \
  59                         | (((x) & 0x00FF0000U) >>  8) \
  60                         | (((x) & 0xFF000000U) >> 24) )
  61 #endif
  62
  63 /*
  64  * Using GETBITS() and PUTBITS() inside a loop mightn't be such a good idea.
  65  * There's probably some CSE and strength-reduction that the compiler won't
  66  * even think about - really should have a few assumptions/separate cases.
  67  */
  68
  69 /* Get a number of bits ( <= 32 ) from *sp and store in dw */
  70 #define GETBITS(sp, x, w, dw) do {                                      \
  71         dw = MBL(*(sp), (x));                                           \
  72         if (((x) + (w)) > 32)                                           \
  73                 dw |= (MBR((sp)[1], 32 - (x)));                         \
  74 } while(0);
  75
  76 /* Put a number of bits ( <= 32 ) from sw to *dp */
  77 #define PUTBITS(sw, x, w, dp) do {                                      \
  78         int n = (x) + (w) - 32;                                         \
  79                                                                         \
  80         if (n <= 0) {                                                   \
  81                 n = rasops_pmask[x & 31][w & 31];                       \
  82                 *(dp) = (*(dp) & ~n) | (MBR(sw, x) & n);                \
  83         } else {                                                        \
  84                 *(dp) = (*(dp) & rasops_rmask[x]) | (MBR((sw), x));     \
  85                 (dp)[1] = ((dp)[1] & rasops_rmask[n]) |                 \
  86                         (MBL(sw, 32-(x)) & rasops_lmask[n]);            \
  87         }                                                               \
  88 } while(0);
  89
  90 /* rasops_masks.c */
  91 extern const int32_t    rasops_lmask[32+1];
  92 extern const int32_t    rasops_rmask[32+1];
  93 extern const int32_t    rasops_pmask[32][32];
  94
  95 #endif /* _RASOPS_MASKS_H_ */