sms: improve irq handling
[picodrive.git] / pico / sms.c
CommitLineData
cff531af 1/*
2 * SMS emulation
3 * (C) notaz, 2009-2010
4 *
5 * This work is licensed under the terms of MAME license.
6 * See COPYING file in the top-level directory.
7 */
87b0845f 8/*
9 * TODO:
10 * - start in a state as if BIOS ran
87b0845f 11 * - RAM support in mapper
12 * - region support
87b0845f 13 * - H counter
14 */
3e49ffd0 15#include "pico_int.h"
af37bca8 16#include "memory.h"
2ec9bec5 17#include "sound/sn76496.h"
3e49ffd0 18
2ec9bec5 19static unsigned char vdp_data_read(void)
3e49ffd0 20{
2ec9bec5 21 struct PicoVideo *pv = &Pico.video;
22 unsigned char d;
23
88fd63ad 24 d = PicoMem.vramb[pv->addr];
2ec9bec5 25 pv->addr = (pv->addr + 1) & 0x3fff;
26 pv->pending = 0;
27 return d;
28}
29
30static unsigned char vdp_ctl_read(void)
31{
1c25c32c 32 struct PicoVideo *pv = &Pico.video;
33 unsigned char d;
34
cf83610b 35 z80_int_assert(0);
1c25c32c 36 d = pv->status | (pv->pending_ints << 7);
37 pv->pending = pv->pending_ints = 0;
38 pv->status = 0;
2ec9bec5 39
40 elprintf(EL_SR, "VDP sr: %02x", d);
41 return d;
42}
43
44static void vdp_data_write(unsigned char d)
45{
46 struct PicoVideo *pv = &Pico.video;
47
48 if (pv->type == 3) {
88fd63ad 49 PicoMem.cram[pv->addr & 0x1f] = d;
200772b7 50 Pico.m.dirtyPal = 1;
2ec9bec5 51 } else {
88fd63ad 52 PicoMem.vramb[pv->addr] = d;
2ec9bec5 53 }
54 pv->addr = (pv->addr + 1) & 0x3fff;
2ec9bec5 55
56 pv->pending = 0;
57}
58
cf83610b 59static NOINLINE void vdp_reg_write(struct PicoVideo *pv, u8 a, u8 d)
60{
61 int l;
62
63 pv->reg[a] = d;
64 switch (a) {
65 case 0:
66 l = pv->pending_ints & (d >> 3) & 2;
67 elprintf(EL_INTS, "hint %d", l);
68 z80_int_assert(l);
69 break;
70 case 1:
71 l = pv->pending_ints & (d >> 5) & 1;
72 elprintf(EL_INTS, "vint %d", l);
73 z80_int_assert(l);
74 break;
75 }
76}
77
78static void vdp_ctl_write(u8 d)
2ec9bec5 79{
80 struct PicoVideo *pv = &Pico.video;
81
82 if (pv->pending) {
83 if ((d >> 6) == 2) {
200772b7 84 elprintf(EL_IO, " VDP r%02x=%02x", d & 0x0f, pv->addr & 0xff);
cf83610b 85 if (pv->reg[d & 0x0f] != (u8)pv->addr)
86 vdp_reg_write(pv, d & 0x0f, pv->addr);
2ec9bec5 87 }
88 pv->type = d >> 6;
89 pv->addr &= 0x00ff;
90 pv->addr |= (d & 0x3f) << 8;
91 } else {
92 pv->addr &= 0x3f00;
93 pv->addr |= d;
94 }
95 pv->pending ^= 1;
3e49ffd0 96}
97
2ec9bec5 98static unsigned char z80_sms_in(unsigned short a)
3e49ffd0 99{
2ec9bec5 100 unsigned char d = 0;
101
200772b7 102 elprintf(EL_IO, "z80 port %04x read", a);
2ec9bec5 103 a &= 0xc1;
104 switch (a)
105 {
106 case 0x00:
107 case 0x01:
108 d = 0xff;
109 break;
110
111 case 0x40: /* V counter */
112 d = Pico.video.v_counter;
87b0845f 113 elprintf(EL_HVCNT, "V counter read: %02x", d);
2ec9bec5 114 break;
115
116 case 0x41: /* H counter */
117 d = Pico.m.rotate++;
87b0845f 118 elprintf(EL_HVCNT, "H counter read: %02x", d);
2ec9bec5 119 break;
120
121 case 0x80:
122 d = vdp_data_read();
123 break;
124
125 case 0x81:
126 d = vdp_ctl_read();
127 break;
128
129 case 0xc0: /* I/O port A and B */
93f9619e 130 d = ~((PicoIn.pad[0] & 0x3f) | (PicoIn.pad[1] << 6));
2ec9bec5 131 break;
132
133 case 0xc1: /* I/O port B and miscellaneous */
b4db550e 134 d = (Pico.ms.io_ctl & 0x80) | ((Pico.ms.io_ctl << 1) & 0x40) | 0x30;
93f9619e 135 d |= ~(PicoIn.pad[1] >> 2) & 0x0f;
2ec9bec5 136 break;
137 }
138
200772b7 139 elprintf(EL_IO, "ret = %02x", d);
2ec9bec5 140 return d;
141}
142
143static void z80_sms_out(unsigned short a, unsigned char d)
144{
200772b7 145 elprintf(EL_IO, "z80 port %04x write %02x", a, d);
2ec9bec5 146 a &= 0xc1;
147 switch (a)
148 {
149 case 0x01:
b4db550e 150 Pico.ms.io_ctl = d;
2ec9bec5 151 break;
152
153 case 0x40:
154 case 0x41:
6311a3ba 155 if ((d & 0x90) == 0x90 && Pico.snd.psg_line < Pico.m.scanline)
075672bf 156 PsndDoPSG(Pico.m.scanline);
157 SN76496Write(d);
2ec9bec5 158 break;
159
160 case 0x80:
161 vdp_data_write(d);
162 break;
163
164 case 0x81:
165 vdp_ctl_write(d);
166 break;
167 }
168}
169
87b0845f 170static int bank_mask;
171
2ec9bec5 172static void write_bank(unsigned short a, unsigned char d)
173{
460603fa 174 elprintf(EL_Z80BNK, "bank %04x %02x @ %04x", a, d, z80_pc());
2ec9bec5 175 switch (a & 0x0f)
176 {
177 case 0x0c:
87b0845f 178 elprintf(EL_STATUS|EL_ANOMALY, "%02x written to control reg!", d);
2ec9bec5 179 break;
180 case 0x0d:
181 if (d != 0)
182 elprintf(EL_STATUS|EL_ANOMALY, "bank0 changed to %d!", d);
183 break;
184 case 0x0e:
87b0845f 185 d &= bank_mask;
2ec9bec5 186 z80_map_set(z80_read_map, 0x4000, 0x7fff, Pico.rom + (d << 14), 0);
187#ifdef _USE_CZ80
b8a1c09a 188 Cz80_Set_Fetch(&CZ80, 0x4000, 0x7fff, (FPTR)Pico.rom + (d << 14));
2ec9bec5 189#endif
190 break;
191 case 0x0f:
87b0845f 192 d &= bank_mask;
2ec9bec5 193 z80_map_set(z80_read_map, 0x8000, 0xbfff, Pico.rom + (d << 14), 0);
194#ifdef _USE_CZ80
b8a1c09a 195 Cz80_Set_Fetch(&CZ80, 0x8000, 0xbfff, (FPTR)Pico.rom + (d << 14));
2ec9bec5 196#endif
197 break;
198 }
b4db550e 199 Pico.ms.carthw[a & 0x0f] = d;
3e49ffd0 200}
201
553c3eaa 202static void xwrite(unsigned int a, unsigned char d)
2ec9bec5 203{
200772b7 204 elprintf(EL_IO, "z80 write [%04x] %02x", a, d);
2ec9bec5 205 if (a >= 0xc000)
88fd63ad 206 PicoMem.zram[a & 0x1fff] = d;
b4db550e 207 if (a >= 0xfff8)
2ec9bec5 208 write_bank(a, d);
3e49ffd0 209}
210
2ec9bec5 211void PicoResetMS(void)
3e49ffd0 212{
2ec9bec5 213 z80_reset();
214 PsndReset(); // pal must be known here
3e49ffd0 215}
216
217void PicoPowerMS(void)
218{
87b0845f 219 int s, tmp;
220
88fd63ad 221 memset(&PicoMem,0,sizeof(PicoMem));
2ec9bec5 222 memset(&Pico.video,0,sizeof(Pico.video));
223 memset(&Pico.m,0,sizeof(Pico.m));
224 Pico.m.pal = 0;
225
87b0845f 226 // calculate a mask for bank writes.
227 // ROM loader has aligned the size for us, so this is safe.
228 s = 0; tmp = Pico.romsize;
229 while ((tmp >>= 1) != 0)
230 s++;
231 if (Pico.romsize > (1 << s))
232 s++;
233 tmp = 1 << s;
234 bank_mask = (tmp - 1) >> 14;
235
b4db550e 236 Pico.ms.carthw[0x0e] = 1;
237 Pico.ms.carthw[0x0f] = 2;
238
2ec9bec5 239 PicoReset();
3e49ffd0 240}
241
242void PicoMemSetupMS(void)
243{
244 z80_map_set(z80_read_map, 0x0000, 0xbfff, Pico.rom, 0);
88fd63ad 245 z80_map_set(z80_read_map, 0xc000, 0xdfff, PicoMem.zram, 0);
246 z80_map_set(z80_read_map, 0xe000, 0xffff, PicoMem.zram, 0);
3e49ffd0 247
2ec9bec5 248 z80_map_set(z80_write_map, 0x0000, 0xbfff, xwrite, 1);
88fd63ad 249 z80_map_set(z80_write_map, 0xc000, 0xdfff, PicoMem.zram, 0);
3e49ffd0 250 z80_map_set(z80_write_map, 0xe000, 0xffff, xwrite, 1);
251
252#ifdef _USE_DRZ80
253 drZ80.z80_in = z80_sms_in;
254 drZ80.z80_out = z80_sms_out;
255#endif
256#ifdef _USE_CZ80
b8a1c09a 257 Cz80_Set_Fetch(&CZ80, 0x0000, 0xbfff, (FPTR)Pico.rom);
88fd63ad 258 Cz80_Set_Fetch(&CZ80, 0xc000, 0xdfff, (FPTR)PicoMem.zram);
259 Cz80_Set_Fetch(&CZ80, 0xe000, 0xffff, (FPTR)PicoMem.zram);
3e49ffd0 260 Cz80_Set_INPort(&CZ80, z80_sms_in);
261 Cz80_Set_OUTPort(&CZ80, z80_sms_out);
262#endif
263}
264
b4db550e 265void PicoStateLoadedMS(void)
266{
267 write_bank(0xfffe, Pico.ms.carthw[0x0e]);
268 write_bank(0xffff, Pico.ms.carthw[0x0f]);
269}
270
3e49ffd0 271void PicoFrameMS(void)
272{
2ec9bec5 273 struct PicoVideo *pv = &Pico.video;
274 int is_pal = Pico.m.pal;
275 int lines = is_pal ? 313 : 262;
276 int cycles_line = is_pal ? 58020 : 58293; /* (226.6 : 227.7) * 256 */
277 int cycles_done = 0, cycles_aim = 0;
93f9619e 278 int skip = PicoIn.skipFrame;
2ec9bec5 279 int lines_vis = 192;
87b0845f 280 int hint; // Hint counter
835122bc 281 int nmi;
2ec9bec5 282 int y;
283
4f2cdbf5 284 PsndStartFrame();
285
93f9619e 286 nmi = (PicoIn.pad[0] >> 7) & 1;
835122bc 287 if (!Pico.ms.nmi_state && nmi)
288 z80_nmi();
289 Pico.ms.nmi_state = nmi;
290
200772b7 291 PicoFrameStartMode4();
87b0845f 292 hint = pv->reg[0x0a];
200772b7 293
2ec9bec5 294 for (y = 0; y < lines; y++)
295 {
296 pv->v_counter = Pico.m.scanline = y;
03065bb6 297 if (y > 218)
298 pv->v_counter = y - 6;
2ec9bec5 299
19954be1 300 if (y < lines_vis && !skip)
200772b7 301 PicoLineMode4(y);
87b0845f 302
303 if (y <= lines_vis)
304 {
305 if (--hint < 0)
306 {
307 hint = pv->reg[0x0a];
308 pv->pending_ints |= 2;
309 if (pv->reg[0] & 0x10) {
310 elprintf(EL_INTS, "hint");
cf83610b 311 z80_int_assert(1);
87b0845f 312 }
313 }
314 }
200772b7 315 else if (y == lines_vis + 1) {
87b0845f 316 pv->pending_ints |= 1;
317 if (pv->reg[1] & 0x20) {
2ec9bec5 318 elprintf(EL_INTS, "vint");
cf83610b 319 z80_int_assert(1);
2ec9bec5 320 }
321 }
322
075672bf 323 // 224 because of how it's done for MD...
6311a3ba 324 if (y == 224 && PicoIn.sndOut)
075672bf 325 PsndGetSamplesMS();
326
2ec9bec5 327 cycles_aim += cycles_line;
328 cycles_done += z80_run((cycles_aim - cycles_done) >> 8) << 8;
329 }
330
6311a3ba 331 if (PicoIn.sndOut && Pico.snd.psg_line < lines)
075672bf 332 PsndDoPSG(lines - 1);
3e49ffd0 333}
334
87b0845f 335void PicoFrameDrawOnlyMS(void)
336{
337 int lines_vis = 192;
338 int y;
339
340 PicoFrameStartMode4();
341
342 for (y = 0; y < lines_vis; y++)
343 PicoLineMode4(y);
344}
345
075672bf 346// vim:ts=2:sw=2:expandtab