apps/plugins/zxbox/z80_step.c

   1 /*
   2  * Copyright (C) 1996-1998 Szeredi Miklos
   3  * Email: mszeredi@inf.bme.hu
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version. See the file COPYING.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  *
  19  */
  20
  21 #include "z80_def.h"
  22
  23 byte z80c_incf_tbl[256];
  24 byte z80c_decf_tbl[256];
  25 byte z80c_addf_tbl[256];
  26 byte z80c_subf_tbl[256];
  27 byte z80c_orf_tbl[256];
  28
  29
  30 void PRNM(pushpc)(void)
  31 {
  32 #ifdef PROCP
  33   Z80 *z80p;
  34   z80p = &PRNM(proc);
  35 #endif
  36
  37   SP--;
  38   PUTMEM(SP, SPP, PCH);
  39   SP--;
  40   PUTMEM(SP, SPP, PCL);
  41 }
  42
  43 static int parity(int b)
  44 {
  45   int i;
  46   int par;
  47
  48   par = 0;
  49   for(i = 8; i; i--) par ^= (b & 1), b >>= 1;
  50   return par;
  51 }
  52
  53 void PRNM(local_init)(void)
  54 {
  55   int i;
  56
  57 #ifdef PROCP
  58   Z80 *z80p;
  59   z80p = &PRNM(proc);
  60 #endif
  61
  62   for(i = 0; i < 0x100; i++) {
  63     z80c_incf_tbl[i] = z80c_decf_tbl[i] = z80c_orf_tbl[i] = 0;
  64
  65     z80c_orf_tbl[i] |= i & (SF | B3F | B5F);
  66     z80c_incf_tbl[i] |= i & (SF | B3F | B5F);
  67     z80c_decf_tbl[i] |= i & (SF | B3F | B5F);
  68
  69     if(!parity(i)) z80c_orf_tbl[i] |= PVF;
  70   }
  71
  72   z80c_incf_tbl[0] |= ZF;
  73   z80c_decf_tbl[0] |= ZF;
  74   z80c_orf_tbl[0] |= ZF;
  75
  76   z80c_incf_tbl[0x80] |= PVF;
  77   z80c_decf_tbl[0x7F] |= PVF;
  78
  79   for(i = 0; i < 0x100; i++) {
  80     int cr, c1, c2;
  81     int hr, h1, h2;
  82     int b5r;
  83
  84     cr  = i & 0x80;
  85     c1  = i & 0x40;
  86     b5r = i & 0x20;
  87     c2  = i & 0x10;
  88
  89     hr  = i & 0x08;
  90     h1  = i & 0x04;
  91     h2  = i & 0x01;
  92
  93     z80c_addf_tbl[i] = 0;
  94     z80c_subf_tbl[i] = 0;
  95     if(cr) {
  96       z80c_addf_tbl[i] |= SF;
  97       z80c_subf_tbl[i] |= SF;
  98     }
  99     if(b5r) {
 100       z80c_addf_tbl[i] |= B5F;
 101       z80c_subf_tbl[i] |= B5F;
 102     }
 103     if(hr) {
 104       z80c_addf_tbl[i] |= B3F;
 105       z80c_subf_tbl[i] |= B3F;
 106     }
 107
 108     if((c1 && c2) || (!cr && (c1 || c2))) z80c_addf_tbl[i] |= CF;
 109     if((h1 && h2) || (!hr && (h1 || h2))) z80c_addf_tbl[i] |= HF;
 110
 111     if((!c1 && !c2 && cr) || (c1 && c2 && !cr)) z80c_addf_tbl[i] |= PVF;
 112
 113
 114     if((c2 && cr) || (!c1 && (c2 || cr))) z80c_subf_tbl[i] |= CF;
 115     if((h2 && hr) || (!h1 && (h2 || hr))) z80c_subf_tbl[i] |= HF;
 116
 117     if((!c2 && !cr && c1) || (c2 && cr && !c1)) z80c_subf_tbl[i] |= PVF;
 118
 119
 120     z80c_subf_tbl[i] |= NF;
 121   }
 122
 123
 124 #ifdef PROCP
 125   TAB(incf_tbl) = z80c_incf_tbl;
 126   TAB(decf_tbl) = z80c_decf_tbl;
 127   TAB(addf_tbl) = z80c_addf_tbl;
 128   TAB(subf_tbl) = z80c_subf_tbl;
 129   TAB(orf_tbl) = z80c_orf_tbl;
 130
 131   PORT(inports) = PRNM(inports);
 132   PORT(outports) = PRNM(outports);
 133 #ifdef SPECT_MEM
 134   SPECP(fe_inport_high) = SPNM(fe_inport_high);
 135 #endif
 136 #endif
 137 }
 138
 139
 140 int PRNM(step)(int tc)
 141 {
 142 #ifdef PROCP
 143   Z80 *z80p;
 144   z80p = &PRNM(proc);
 145 #endif
 146
 147   DANM(tc) = tc;
 148   DANM(rl7) = RR & 0x80;
 149
 150   if(DANM(haltstate)) {
 151     register int nn;
 152     nn = (DANM(tc) - 1) / 4 + 1;
 153
 154     DANM(tc) -= 4 * nn;
 155     RR += nn;
 156   }
 157   else do {
 158     register int nextop;
 159
 160 #ifdef DEBUG_Z80
 161     debug_z80();
 162 #endif
 163     nextop = *PCP;
 164     PC++;
 165
 166 #ifdef PROCP
 167     z80p = (*z80c_op_tab[nextop])(z80p);
 168 #else
 169     (*z80c_op_tab[nextop])();
 170 #endif
 171     RR++;
 172   } while(DANM(tc) > 0);
 173
 174   RR = (RR & 0x7F) | DANM(rl7);
 175   return DANM(tc);
 176 }