1 files changed, 176 insertions, 0 deletions

diff --git a/apps/plugins/zxbox/z80_step.c b/apps/plugins/zxbox/z80_step.c
new file mode 100644
index 0000000000..803079c970
--- /dev/null
+++ b/apps/plugins/zxbox/z80_step.c
@@ -0,0 +1,176 @@
+/* 
+ * Copyright (C) 1996-1998 Szeredi Miklos
+ * Email: mszeredi@inf.bme.hu
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version. See the file COPYING. 
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include "z80_def.h"
+
+byte z80c_incf_tbl[256];
+byte z80c_decf_tbl[256];
+byte z80c_addf_tbl[256];
+byte z80c_subf_tbl[256];
+byte z80c_orf_tbl[256];
+
+
+void PRNM(pushpc)(void)
+{
+#ifdef PROCP
+  Z80 *z80p;
+  z80p = &PRNM(proc);
+#endif
+
+  SP--;
+  PUTMEM(SP, SPP, PCH);
+  SP--;
+  PUTMEM(SP, SPP, PCL);
+}
+
+static int parity(int b)
+{
+  int i;
+  int par;
+  
+  par = 0;
+  for(i = 8; i; i--) par ^= (b & 1), b >>= 1;
+  return par;
+}
+
+void PRNM(local_init)(void)
+{
+  int i;
+
+#ifdef PROCP
+  Z80 *z80p;
+  z80p = &PRNM(proc);
+#endif
+
+  for(i = 0; i < 0x100; i++) {
+    z80c_incf_tbl[i] = z80c_decf_tbl[i] = z80c_orf_tbl[i] = 0;
+
+    z80c_orf_tbl[i] |= i & (SF | B3F | B5F);
+    z80c_incf_tbl[i] |= i & (SF | B3F | B5F);
+    z80c_decf_tbl[i] |= i & (SF | B3F | B5F);
+
+    if(!parity(i)) z80c_orf_tbl[i] |= PVF;
+  }
+
+  z80c_incf_tbl[0] |= ZF;
+  z80c_decf_tbl[0] |= ZF;
+  z80c_orf_tbl[0] |= ZF;
+
+  z80c_incf_tbl[0x80] |= PVF;
+  z80c_decf_tbl[0x7F] |= PVF;
+
+  for(i = 0; i < 0x100; i++) {
+    int cr, c1, c2;
+    int hr, h1, h2;
+    int b5r;
+    
+    cr  = i & 0x80;
+    c1  = i & 0x40;
+    b5r = i & 0x20;
+    c2  = i & 0x10;
+
+    hr  = i & 0x08;
+    h1  = i & 0x04;
+    h2  = i & 0x01;
+
+    z80c_addf_tbl[i] = 0;
+    z80c_subf_tbl[i] = 0;
+    if(cr) {
+      z80c_addf_tbl[i] |= SF;
+      z80c_subf_tbl[i] |= SF;
+    }
+    if(b5r) {
+      z80c_addf_tbl[i] |= B5F;
+      z80c_subf_tbl[i] |= B5F;
+    }
+    if(hr) {
+      z80c_addf_tbl[i] |= B3F;
+      z80c_subf_tbl[i] |= B3F;
+    }
+  
+    if((c1 && c2) || (!cr && (c1 || c2))) z80c_addf_tbl[i] |= CF;
+    if((h1 && h2) || (!hr && (h1 || h2))) z80c_addf_tbl[i] |= HF;
+
+    if((!c1 && !c2 && cr) || (c1 && c2 && !cr)) z80c_addf_tbl[i] |= PVF;
+
+
+    if((c2 && cr) || (!c1 && (c2 || cr))) z80c_subf_tbl[i] |= CF;
+    if((h2 && hr) || (!h1 && (h2 || hr))) z80c_subf_tbl[i] |= HF;
+    
+    if((!c2 && !cr && c1) || (c2 && cr && !c1)) z80c_subf_tbl[i] |= PVF;
+
+    
+    z80c_subf_tbl[i] |= NF;
+  }
+  
+
+#ifdef PROCP
+  TAB(incf_tbl) = z80c_incf_tbl;
+  TAB(decf_tbl) = z80c_decf_tbl;
+  TAB(addf_tbl) = z80c_addf_tbl;
+  TAB(subf_tbl) = z80c_subf_tbl;
+  TAB(orf_tbl) = z80c_orf_tbl;
+
+  PORT(inports) = PRNM(inports);
+  PORT(outports) = PRNM(outports);
+#ifdef SPECT_MEM
+  SPECP(fe_inport_high) = SPNM(fe_inport_high);
+#endif
+#endif
+}
+
+
+int PRNM(step)(int tc)
+{
+#ifdef PROCP
+  Z80 *z80p;
+  z80p = &PRNM(proc);
+#endif
+
+  DANM(tc) = tc;
+  DANM(rl7) = RR & 0x80;
+
+  if(DANM(haltstate)) {
+    register int nn;
+    nn = (DANM(tc) - 1) / 4 + 1;
+    
+    DANM(tc) -= 4 * nn;
+    RR += nn;
+  }
+  else do {
+    register int nextop;
+
+#ifdef DEBUG_Z80
+    debug_z80();
+#endif
+    nextop = *PCP; 
+    PC++;
+
+#ifdef PROCP
+    z80p = (*z80c_op_tab[nextop])(z80p);
+#else
+    (*z80c_op_tab[nextop])();
+#endif
+    RR++; 
+  } while(DANM(tc) > 0);
+
+  RR = (RR & 0x7F) | DANM(rl7);
+  return DANM(tc);
+}