dmd2/bit.c

   1
   2 // Copyright (c) 1999-2002 by Digital Mars
   3 // All Rights Reserved
   4 // written by Walter Bright
   5 // http://www.digitalmars.com
   6 // License for redistribution is by either the Artistic License
   7 // in artistic.txt, or the GNU General Public License in gnu.txt.
   8 // See the included readme.txt for details.
   9
  10 // Routines to convert expressions to elems.
  11
  12 #include        <stdio.h>
  13 #include        <string.h>
  14 #include        <time.h>
  15
  16 #include        "cc.h"
  17 #include        "el.h"
  18 #include        "oper.h"
  19 #include        "global.h"
  20 #include        "code.h"
  21 #include        "type.h"
  22 #include        "dt.h"
  23
  24 static char __file__[] = __FILE__;      /* for tassert.h                */
  25 #include        "tassert.h"
  26
  27 /**********************************************
  28  * Generate code for:
  29  *      (*eb)[ei] = ev;
  30  * ev should already be a bit type.
  31  * result:
  32  *      0       don't want result
  33  *      1       want result in flags
  34  *      2       want value of result
  35  */
  36
  37 #if 1
  38 #define BIT_SHIFT       3
  39 #define BIT_MASK        7
  40 #define TYbit           TYuchar
  41 #else
  42 #define BIT_SHIFT       5
  43 #define BIT_MASK        31
  44 #define TYbit           TYuint
  45 #endif
  46
  47 elem *bit_assign(enum OPER op, elem *eb, elem *ei, elem *ev, int result)
  48 {
  49 #if 1
  50     elem *e;
  51     elem *es;
  52     elem *er;
  53
  54     es = el_bin(OPbts, TYbit, eb, ei);
  55     er = el_copytree(es);
  56     er->Eoper = OPbtr;
  57     es = el_bin(OPcomma, TYbit, es, el_long(TYbit, 1));
  58     er = el_bin(OPcomma, TYbit, er, el_long(TYbit, 0));
  59
  60     e = el_bin(OPcolon, TYvoid, es, er);
  61     e = el_bin(OPcond, ev->Ety, ev, e);
  62     return e;
  63 #else
  64     /*
  65         The idea is:
  66
  67         *(eb + (ei >> 5)) &= ~(1 << (ei & 31));
  68         *(eb + (ei >> 5)) |= ev << (ei & 31);
  69         ev;
  70
  71         So we generate:
  72
  73         et = (eb + (ei >> 5));
  74         em = (eit & 31);
  75         *ett = (*et & ~(1 << em)) | (ev << em);
  76         evt;
  77      */
  78
  79     printf("bit_assign()\n");
  80
  81     elem *e;
  82     elem *em;
  83     elem *eit = el_same(&ei);
  84     elem *et;
  85     elem *ett;
  86     elem *evt = el_same(&ev);
  87
  88     ei->Ety = TYuint;
  89     et = el_bin(OPshr, TYuint, ei, el_long(TYuint, BIT_SHIFT));
  90     et = el_bin(OPadd, TYnptr, eb, et);
  91     ett = el_same(&et);
  92
  93     eit->Ety = TYbit;
  94     em = el_bin(OPand, TYbit, eit, el_long(TYbit, BIT_MASK));
  95
  96     e = el_bin(OPshl, TYbit, el_long(TYbit, 1), em);
  97     e = el_una(OPcom, TYbit, e);
  98     et = el_una(OPind, TYbit, et);
  99     e = el_bin(OPand, TYbit, et, e);
 100
 101     ev->Ety = TYbit;
 102     e = el_bin(OPor, TYbit, e, el_bin(OPshl, TYbit, ev, el_copytree(em)));
 103     ett = el_una(OPind, TYbit, ett);
 104     e = el_bin(OPeq, TYbit, ett, e);
 105
 106     e = el_bin(OPcomma, evt->Ety, e, evt);
 107     return e;
 108 #endif
 109 }
 110
 111 /**********************************************
 112  * Generate code for:
 113  *      (*eb)[ei]
 114  * ev should already be a bit type.
 115  * result:
 116  *      0       don't want result
 117  *      1       want result in flags
 118  *      2       want value of result
 119  *      3       ?
 120  */
 121
 122 elem *bit_read(elem *eb, elem *ei, int result)
 123 {
 124 #if 1
 125     elem *e;
 126
 127     e = el_bin(OPbt, TYbit, eb, ei);
 128     e = el_bin(OPand, TYbit, e, el_long(TYbit, 1));
 129     return e;
 130 #else
 131     // eb[ei] => (eb[ei >>> 5] >> (ei & 31)) & 1
 132     elem *e;
 133     elem *eit = el_same(&ei);
 134
 135     // Now generate ((*(eb + (ei >>> 5)) >>> (eit & 31)) & 1
 136
 137     ei->Ety = TYuint;
 138     e = el_bin(OPshr, TYuint, ei, el_long(TYuint, BIT_SHIFT));
 139     e = el_bin(OPadd, TYnptr, eb, e);
 140     e = el_una(OPind, TYbit, e);
 141     eit->Ety = TYbit;
 142     eit = el_bin(OPand, TYbit, eit, el_long(TYbit, BIT_MASK));
 143     e = el_bin(OPshr, TYbit, e, eit);
 144     e = el_bin(OPand, TYbit, e, el_long(TYbit, 1));
 145
 146     // BUG: what about return type of e?
 147     return e;
 148 #endif
 149 }