mach/6805/as/mach5.c

   1 /*
   2  * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
   3  * See the copyright notice in the ACK home directory, in the file "Copyright".
   4  */
   5 #define RCSID5 "$Id: mach5.c,v 0.3 1994/06/24 12:55:56 ceriel Exp $"
   6
   7 /*
   8  * Motorola 6805 special routines
   9  */
  10
  11 /* VARARGS2 */
  12 branch(opc,exp,cell) register opc; expr_t cell; expr_t exp; {
  13         register sm, dist;
  14         int saving;
  15
  16         dist = exp.val - (DOTVAL + 2);
  17         if((opc & 0xf0) == 0) dist -= 1;  /* bitbranch */
  18         if (pass == PASS_2 && dist > 0 && !(exp.typ & S_DOT))
  19                 dist -= DOTGAIN;
  20         sm = fitj(dist);
  21         if ((exp.typ & ~S_DOT) != DOTTYP)
  22                 sm = 0;
  23         if (opc == 0x20 || opc == 0xAD)
  24                 saving = 1;
  25         else
  26                 saving = 3;
  27         if (small(sm,saving)) {
  28                 emit1(opc);
  29                 if((opc & 0xF0) == 0)   /* bit branch */
  30                         emit1(cell.val);
  31 #ifdef RELOCATION
  32                 newrelo(exp.typ, RELPC|RELO1);
  33 #endif
  34                 emit1(dist);
  35         } else {
  36                 if (opc == 0xAD)                /* bsr */
  37                         emit1(0xBD);            /* jsr */
  38                 else {
  39                         if (opc != 0x20) {      /* bra */
  40
  41                                         /* reverse condition : */
  42
  43                                 emit1(opc ^ 1);
  44                                 if((opc & 0xF0) == 0)  /* bitbranch */
  45                                         emit1(cell.val);
  46                                 emit1(3);
  47                         }
  48                         emit1(0xCC);            /* jmp */
  49                 }
  50 #ifdef RELOCATION
  51                 newrelo(exp.typ, RELPC|RELO2|RELBR);
  52 #endif
  53                 emit2(exp.val);
  54         }
  55 }