1 /* Emulation of the Z80 CPU with hooks into the other parts of aylet.
2 * Copyright (C) 1994 Ian Collier. aylet changes (C) 2001-2002 Russell Marks.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17 */
18
19 #include <stdio.h>
20 #include <signal.h>
21 #include <unistd.h>
22 #include "main.h"
23 #include "z80.h"
24
25 #define parity(a) (partable[a])
26
27 unsigned char partable[256]={
28 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
29 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
30 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
31 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
32 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
33 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
34 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
35 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
36 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
37 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
38 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
39 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
40 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
41 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
42 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
43 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4
44 };
45
46
z80loop(unsigned char * data,unsigned char * stacketc)47 void z80loop(unsigned char *data,unsigned char *stacketc)
48 {
49 unsigned char a, f, b, c, d, e, h, l;
50 unsigned char r, a1, f1, b1, c1, d1, e1, h1, l1, i, iff1, iff2, im;
51 unsigned short pc;
52 unsigned short ix, iy, sp;
53 unsigned int radjust;
54 unsigned int ixoriy, new_ixoriy;
55 unsigned int intsample;
56 unsigned char op;
57 int interrupted=0;
58
59 a=f=b=c=d=e=h=l=a1=f1=b1=c1=d1=e1=h1=l1=i=r=iff1=iff2=im=0;
60 ixoriy=new_ixoriy=0;
61 ix=iy=sp=pc=0;
62 tstates=0;
63 radjust=0;
64
65 a=a1=b=b1=d=d1=h=h1=data[8];
66 f=f1=c=c1=e=e1=l=l1=data[9];
67 ix=iy=hl;
68
69 sp=stacketc[0]*256+stacketc[1];
70
71 while(1)
72 {
73 if(tstates>=tsmax)
74 {
75 do
76 {
77 if(!do_interrupt())
78 {
79 /* they want to exit */
80 return;
81 }
82 }
83 while(playing && paused); /* when it's paused, we'd better wait here */
84
85 tstates-=tsmax;
86 interrupted=1;
87 }
88
89 ixoriy=new_ixoriy;
90 new_ixoriy=0;
91 intsample=1;
92 op=fetch(pc);
93 pc++;
94 radjust++;
95 switch(op)
96 {
97 #include "z80ops.c"
98 }
99
100 if(interrupted && intsample && iff1)
101 {
102 interrupted=0;
103 if(fetch(pc)==0x76)pc++;
104 iff1=iff2=0;
105 tstates+=5; /* accompanied by an input from the data bus */
106 switch(im)
107 {
108 case 0: /* IM 0 */
109 case 1: /* undocumented */
110 case 2: /* IM 1 */
111 /* there is little to distinguish between these cases */
112 tstates+=7; /* perhaps */
113 push2(pc);
114 pc=0x38;
115 break;
116 case 3: /* IM 2 */
117 tstates+=13; /* perhaps */
118 {
119 int addr=fetch2((i<<8)|0xff);
120 push2(pc);
121 pc=addr;
122 }
123 }
124 }
125 }
126 }
127