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sound, improve ym2612 timers implementation
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kub
parent
914525c3d5
commit
0e2e188e1e
2 changed files with 47 additions and 33 deletions
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@ -1041,7 +1041,7 @@ static int get_scanline(int is_from_z80)
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if (is_from_z80) {
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// ugh... compute by dividing cycles since frame start by cycles per line
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// need some fractional resolution here, else there may be an extra line
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int cycles_line = cycles_68k_to_z80(488 << 8); // cycles per line, as Q8
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int cycles_line = cycles_68k_to_z80(488 << 8)+1; // cycles per line, as Q8
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int cycles_z80 = (z80_cyclesLeft<0 ? Pico.t.z80c_aim:z80_cyclesDone())<<8;
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int cycles = cycles_line * Pico.t.z80_scanline;
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// approximation by multiplying with inverse
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@ -1063,45 +1063,65 @@ static int get_scanline(int is_from_z80)
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return Pico.m.scanline;
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}
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#define ym2612_update_status(xcycles) \
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if (xcycles >= Pico.t.timer_a_next_oflow) \
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ym2612.OPN.ST.status |= (ym2612.OPN.ST.mode >> 2) & 1; \
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if (xcycles >= Pico.t.timer_b_next_oflow) \
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ym2612.OPN.ST.status |= (ym2612.OPN.ST.mode >> 2) & 2
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/* probably should not be in this file, but it's near related code here */
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void ym2612_sync_timers(int z80_cycles, int mode_old, int mode_new)
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{
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int xcycles = z80_cycles << 8;
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/* check for overflows */
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if ((mode_old & 4) && xcycles >= Pico.t.timer_a_next_oflow)
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ym2612.OPN.ST.status |= 1;
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// update timer status
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ym2612_update_status(xcycles);
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if ((mode_old & 8) && xcycles >= Pico.t.timer_b_next_oflow)
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ym2612.OPN.ST.status |= 2;
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/* update timer a */
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// update timer a
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if (mode_old & 1)
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while (xcycles > Pico.t.timer_a_next_oflow)
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while (xcycles >= Pico.t.timer_a_next_oflow)
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Pico.t.timer_a_next_oflow += Pico.t.timer_a_step;
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if ((mode_old ^ mode_new) & 1) // turning on/off
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// turning on/off
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if ((mode_old ^ mode_new) & 1)
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{
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if (mode_old & 1)
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Pico.t.timer_a_next_oflow = TIMER_NO_OFLOW;
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else
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Pico.t.timer_a_next_oflow = xcycles + Pico.t.timer_a_step;
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else {
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/* The internal tick of the YM2612 takes 144 clock cycles (with clock
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* being OSC/7), or 67.2 z80 cycles. Timers are run once each tick.
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* Starting a timer takes place at the next tick, so xcycles needs to be
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* rounded up to that: t = next tick# = (xcycles / TICK_ZCYCLES) + 1
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*/
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unsigned t = ((xcycles * (((1<<20)/TIMER_A_TICK_ZCYCLES)+1))>>20) + 1;
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Pico.t.timer_a_next_oflow = t*TIMER_A_TICK_ZCYCLES + Pico.t.timer_a_step;
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}
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}
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if (mode_new & 1)
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elprintf(EL_YMTIMER, "timer a upd to %i @ %i", Pico.t.timer_a_next_oflow>>8, z80_cycles);
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/* update timer b */
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// update timer b
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if (mode_old & 2)
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while (xcycles > Pico.t.timer_b_next_oflow)
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while (xcycles >= Pico.t.timer_b_next_oflow)
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Pico.t.timer_b_next_oflow += Pico.t.timer_b_step;
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// turning on/off
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if ((mode_old ^ mode_new) & 2)
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{
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if (mode_old & 2)
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Pico.t.timer_b_next_oflow = TIMER_NO_OFLOW;
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else
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Pico.t.timer_b_next_oflow = xcycles + Pico.t.timer_b_step;
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else {
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/* timer b has a divider of 16 which runs in its own counter. It is not
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* reset by loading timer b. The first run of timer b after loading is
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* therefore shorter by up to 15 ticks.
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*/
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unsigned t = ((xcycles * (((1<<20)/TIMER_A_TICK_ZCYCLES)+1))>>20) + 1;
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int step = Pico.t.timer_b_step - TIMER_A_TICK_ZCYCLES*(t&15);
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Pico.t.timer_b_next_oflow = t*TIMER_A_TICK_ZCYCLES + step;
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}
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}
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if (mode_new & 2)
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elprintf(EL_YMTIMER, "timer b upd to %i @ %i", Pico.t.timer_b_next_oflow>>8, z80_cycles);
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}
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@ -1130,6 +1150,7 @@ static int ym2612_write_local(u32 a, u32 d, int is_from_z80)
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switch (addr)
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{
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// NB, OD2 A/V sync HACK: lower timer step by 1/4 z80 cycle (=64 in Q8)
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case 0x24: // timer A High 8
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case 0x25: { // timer A Low 2
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int TAnew = (addr == 0x24) ? ((ym2612.OPN.ST.TA & 0x03)|(((int)d)<<2))
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@ -1142,7 +1163,7 @@ static int ym2612_write_local(u32 a, u32 d, int is_from_z80)
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ym2612.OPN.ST.TA = TAnew;
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//ym2612.OPN.ST.TAC = (1024-TAnew)*18;
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//ym2612.OPN.ST.TAT = 0;
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Pico.t.timer_a_step = TIMER_A_TICK_ZCYCLES * (1024 - TAnew);
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Pico.t.timer_a_step = TIMER_A_TICK_ZCYCLES * (1024 - TAnew) - 64;
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elprintf(EL_YMTIMER, "timer a set to %i, %i", 1024 - TAnew, Pico.t.timer_a_next_oflow>>8);
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}
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return 0;
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@ -1155,7 +1176,7 @@ static int ym2612_write_local(u32 a, u32 d, int is_from_z80)
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ym2612.OPN.ST.TB = d;
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//ym2612.OPN.ST.TBC = (256-d) * 288;
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//ym2612.OPN.ST.TBT = 0;
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Pico.t.timer_b_step = TIMER_B_TICK_ZCYCLES * (256 - d); // 262800
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Pico.t.timer_b_step = TIMER_B_TICK_ZCYCLES * (256 - d) - 64;
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elprintf(EL_YMTIMER, "timer b set to %i, %i", 256 - d, Pico.t.timer_b_next_oflow>>8);
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}
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return 0;
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@ -1163,11 +1184,11 @@ static int ym2612_write_local(u32 a, u32 d, int is_from_z80)
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int old_mode = ym2612.OPN.ST.mode;
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int cycles = is_from_z80 ? z80_cyclesDone() : z80_cycles_from_68k();
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ym2612.OPN.ST.mode = d;
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elprintf(EL_YMTIMER, "st mode %02x", d);
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ym2612_sync_timers(cycles, old_mode, d);
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ym2612.OPN.ST.mode = d;
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/* reset Timer a flag */
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if (d & 0x10)
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ym2612.OPN.ST.status &= ~1;
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@ -1213,17 +1234,11 @@ static int ym2612_write_local(u32 a, u32 d, int is_from_z80)
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}
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#define ym2612_read_local() \
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if (xcycles >= Pico.t.timer_a_next_oflow) \
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ym2612.OPN.ST.status |= (ym2612.OPN.ST.mode >> 2) & 1; \
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if (xcycles >= Pico.t.timer_b_next_oflow) \
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ym2612.OPN.ST.status |= (ym2612.OPN.ST.mode >> 2) & 2
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static u32 ym2612_read_local_z80(void)
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{
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int xcycles = z80_cyclesDone() << 8;
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ym2612_read_local();
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ym2612_update_status(xcycles);
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elprintf(EL_YMTIMER, "timer z80 read %i, sched %i, %i @ %i|%i",
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ym2612.OPN.ST.status, Pico.t.timer_a_next_oflow >> 8,
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@ -1235,7 +1250,7 @@ static u32 ym2612_read_local_68k(void)
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{
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int xcycles = z80_cycles_from_68k() << 8;
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ym2612_read_local();
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ym2612_update_status(xcycles);
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elprintf(EL_YMTIMER, "timer 68k read %i, sched %i, %i @ %i|%i",
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ym2612.OPN.ST.status, Pico.t.timer_a_next_oflow >> 8,
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@ -873,16 +873,15 @@ void ym2612_unpack_state(void);
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#define TIMER_NO_OFLOW 0x70000000
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// NB ~0.2% timers speed up (1/8(A), 2(B) z80 cycles), HACK for A/V sync in OD2
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// tA = 72 * (1024 - TA) / M, with M = mclock/2
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#define TIMER_A_TICK_ZCYCLES (cycles_68k_to_z80(256LL* 72*2)-32) // Q8
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#define TIMER_A_TICK_ZCYCLES cycles_68k_to_z80(256LL* 72*2) // Q8
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// tB = 16*72 * ( 256 - TB) / M
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#define TIMER_B_TICK_ZCYCLES (cycles_68k_to_z80(256LL*16*72*2)-32*16) // Q8
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#define TIMER_B_TICK_ZCYCLES cycles_68k_to_z80(256LL*16*72*2) // Q8
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#define timers_cycle(ticks) \
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if (Pico.t.timer_a_next_oflow > 0 && Pico.t.timer_a_next_oflow < TIMER_NO_OFLOW) \
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if (Pico.t.timer_a_next_oflow < TIMER_NO_OFLOW) \
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Pico.t.timer_a_next_oflow -= ticks << 8; \
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if (Pico.t.timer_b_next_oflow > 0 && Pico.t.timer_b_next_oflow < TIMER_NO_OFLOW) \
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if (Pico.t.timer_b_next_oflow < TIMER_NO_OFLOW) \
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Pico.t.timer_b_next_oflow -= ticks << 8; \
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ym2612_sync_timers(0, ym2612.OPN.ST.mode, ym2612.OPN.ST.mode);
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