--- /dev/null
+/*
+ * PicoDrive
+ * (C) irixxxx, 2024
+ *
+ * MEGASD enhancement support
+ */
+
+#include "../pico_int.h"
+#include "../memory.h"
+
+#include "genplus_macros.h"
+#include "cdd.h"
+#include "megasd.h"
+
+// modifiable fields visible through the interface
+u16 msd_command, msd_result;
+u16 msd_data[0x800/2];
+
+// internal state
+static int msd_initialized;
+static s32 msd_startlba, msd_endlba, msd_looplba;
+static s32 msd_readlba = -1; // >= 0 if sector read is running
+static int msd_loop, msd_index = -1; // >= 0 if audio track is playing
+
+static u16 verser[] = // mimick version 1.04 R7, serial 0x01234567
+ { 0x4d45, 0x4741, 0x5344, 0x0104, 0x0700, 0xffff, 0x0123, 0x4567 };
+// { 0x4d45, 0x4741, 0x5344, 0x9999, 0x9900, 0xffff, 0x1234, 0x5678 };
+
+// get a 32bit value from the data area
+static s32 get32(int offs)
+{
+ u16 *a = msd_data + (offs/2);
+ return (a[0] << 16) | a[1];
+}
+
+// send commands to cdd
+static void cdd_play(s32 lba)
+{
+ int secs = lba / 75;
+ int mins = secs / 60;
+ lba -= secs * 75;
+ secs -= mins * 60;
+ s68k_write8(0xff8044, mins/10);
+ s68k_write8(0xff8045, mins%10);
+ s68k_write8(0xff8046, secs/10);
+ s68k_write8(0xff8047, secs%10);
+ s68k_write8(0xff8048, lba /10);
+ s68k_write8(0xff8049, lba %10);
+
+ s68k_write8(0xff8042, 0x03);
+ s68k_write8(0xff804b, 0xff);
+}
+
+static void cdd_pause(void)
+{
+ s68k_write8(0xff8042, 0x06);
+ s68k_write8(0xff804b, 0xff);
+}
+
+static void cdd_resume(void)
+{
+ s68k_write8(0xff8042, 0x07);
+ s68k_write8(0xff804b, 0xff);
+}
+
+static void cdd_stop(void)
+{
+ msd_index = msd_readlba = -1;
+ s68k_write8(0xff8042, 0x01);
+ s68k_write8(0xff804b, 0xff);
+}
+
+// play a track, looping from offset if enabled
+static void msd_playtrack(int idx, s32 offs, int loop)
+{
+ msd_index = idx-1;
+ msd_loop = loop;
+ msd_readlba = -1;
+
+ msd_startlba = cdd.toc.tracks[msd_index].start + 150;
+ msd_endlba = cdd.toc.tracks[msd_index].end;
+ msd_looplba = msd_startlba + offs;
+
+ cdd_play(msd_startlba);
+}
+
+// play a range of sectors, with looping if enabled
+static void msd_playsectors(s32 startlba, s32 endlba, s32 looplba, int loop)
+{
+ msd_index = 99;
+ msd_loop = loop;
+ msd_readlba = -1;
+
+ msd_startlba = startlba + 150;
+ msd_endlba = endlba + 150;
+ msd_looplba = looplba + 150;
+
+ cdd_play(msd_startlba);
+}
+
+// read a block of data
+static void msd_readdata(s32 lba)
+{
+ msd_index = -1;
+ msd_readlba = lba;
+
+ cdd_play(msd_readlba);
+}
+
+// transfer data to data area
+static void msd_transfer()
+{
+ if (cdd.status == CD_PLAY)
+ cdd_read_data((u8 *)msd_data);
+}
+
+// update msd state (called every 1/75s)
+void msd_update()
+{
+ if (msd_initialized) {
+ // CD LEDs
+ s68k_write8(0xff8000,(cdd.status == CD_PLAY) | 0x2);
+
+ if (cdd.status == CD_PLAY) {
+ if (msd_readlba >= 0 && cdd.lba >= msd_readlba) {
+ // read done
+ msd_command = 0;
+ }
+ else if (msd_index >= 0) {
+ msd_command = 0;
+ if (cdd.lba > msd_endlba || cdd.index > msd_index) {
+ if (!msd_loop || msd_index < 0) {
+ cdd_stop();
+ // audio done
+ } else
+ cdd_play(msd_looplba);
+ }
+ }
+ }
+ }
+}
+
+// process a MEGASD command
+void msd_process(u16 d)
+{
+ msd_command = d; // busy
+
+ switch (d >> 8) {
+ case 0x10: memcpy(msd_data, verser, sizeof(verser)); msd_command = 0; break;
+
+ case 0x11: msd_playtrack(d&0xff, 0, 0); break;
+ case 0x12: msd_playtrack(d&0xff, 0, 1); break;
+ case 0x1a: msd_playtrack(d&0xff, get32(0), 1); break;
+ case 0x1b: msd_playsectors(get32(0), get32(4), get32(8), d&0xff); break;
+
+ case 0x13: cdd_pause();
+ msd_command = 0; break;
+ case 0x14: cdd_resume();
+ msd_command = 0; break;
+
+ case 0x16: msd_result = !(s68k_read8(0xff8036) & 0x1) << 8;
+ msd_command = 0; break;
+
+ case 0x17: msd_readdata(get32(0)); break;
+ case 0x18: msd_transfer();
+ msd_command = 0; break;
+ case 0x19: msd_readdata(++msd_readlba); break;
+
+ case 0x27: msd_result = cdd.toc.last << 8;
+ msd_command = 0; break;
+
+ default: msd_command = msd_result = 0; break; // not supported
+ }
+}
+
+// initialize MEGASD
+static void msd_init(void)
+{
+ if (!msd_initialized) {
+ msd_initialized = 1;
+
+ // enable CD drive
+ s68k_write8(0xff8037, 0x4);
+
+ PicoResetHook = msd_reset;
+ }
+}
+
+void msd_reset(void)
+{
+ if (msd_initialized) {
+ msd_initialized = msd_command = 0;
+ cdd_stop();
+
+ s68k_write8(0xff8000, 0x0);
+ s68k_write8(0xff8001, 0x0);
+
+ PicoResetHook = NULL;
+ }
+}
+
+// memory r/w functions
+static u32 msd_read16(u32 a)
+{
+ u16 d = 0;
+
+ if (a >= 0x03f800) {
+ d = msd_data[(a&0x7ff)>>1];
+ } else if (a >= 0x03f7f0) {
+ switch (a&0xe) {
+ case 0x6: d = 0x5241; break; // RA
+ case 0x8: d = 0x5445; break; // TE
+ case 0xc: d = msd_result; break;
+ case 0xe: d = msd_command; break;
+ }
+ } else if (a < Pico.romsize)
+ d = *(u16 *)(Pico.rom + a);
+
+ return d;
+}
+
+static u32 msd_read8(u32 a)
+{
+ u16 d = msd_read16(a);
+
+ if (!(a&1)) d >>= 8;
+ return d;
+}
+
+void msd_write16(u32 a, u32 d)
+{
+ if (a == 0x03f7fa) {
+ // en/disable overlay
+ u32 base = 0x040000-(1<<M68K_MEM_SHIFT);
+ if ((u16)d == 0xcd54) {
+ msd_init();
+ cpu68k_map_set(m68k_read8_map, base, 0x03ffff, msd_read8, 1);
+ cpu68k_map_set(m68k_read16_map, base, 0x03ffff, msd_read16, 1);
+ } else if (Pico.romsize > base) {
+ cpu68k_map_set(m68k_read8_map, base, 0x03ffff, Pico.rom+base, 0);
+ cpu68k_map_set(m68k_read16_map, base, 0x03ffff, Pico.rom+base, 0);
+ }
+ } else if (a == 0x03f7fe) {
+ // command port
+ msd_process(d);
+ } else if (a >= 0x03f800) {
+ // data area
+ msd_data[(a&0x7ff) >> 1] = d;
+ }
+}
+
+void msd_write8(u32 a, u32 d)
+{
+ if (a >= 0x03f800) {
+ // data area
+ ((u8 *)msd_data)[MEM_BE2(a&0x7ff)] = d;
+ }
+}
notaz.gp2x.de / picodrive.git / commitdiff