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add partial 6840ptm readback support to exidy.c [Lord Nightmare]

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This commit is contained in:
Jonathan Gevaryahu 2010-04-09 07:12:18 +00:00
parent 6fd2705453
commit df26aebdaf
1 changed files with 47 additions and 34 deletions
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81
src/mame/audio/exidy.c
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@ -72,7 +72,8 @@ struct sh6840_timer_channel
};
static struct sh6840_timer_channel sh6840_timer[3];
static INT16 sh6840_volume[3];
static UINT8 sh6840_MSB;
static UINT8 sh6840_MSB_latch;
static UINT8 sh6840_LSB_latch;
static UINT8 sh6840_LFSR_oldxor = 0;
static UINT32 sh6840_LFSR_0;
static UINT32 sh6840_LFSR_1;
@ -225,7 +226,8 @@ INLINE int sh6840_update_noise(int clocks)
static void sh6840_register_state_globals(running_machine *machine)
{
state_save_register_global_array(machine, sh6840_volume);
state_save_register_global(machine, sh6840_MSB);
state_save_register_global(machine, sh6840_MSB_latch);
state_save_register_global(machine, sh6840_LSB_latch);
state_save_register_global(machine, sh6840_LFSR_oldxor);
state_save_register_global(machine, sh6840_LFSR_0);
state_save_register_global(machine, sh6840_LFSR_1);
@ -263,6 +265,7 @@ static void sh6840_register_state_globals(running_machine *machine)
static STREAM_UPDATE( exidy_stream_update )
{
/* hack to skip the expensive lfsr noise generation unless at least one of the 3 channels actually depends on it being generated */
int noisy = ((sh6840_timer[0].cr & sh6840_timer[1].cr & sh6840_timer[2].cr & 0x02) == 0);
stream_sample_t *buffer = outputs[0];
@ -272,6 +275,7 @@ static STREAM_UPDATE( exidy_stream_update )
struct sh6840_timer_channel *t;
struct sh8253_timer_channel *c;
int clocks_this_sample;
int clocks;
INT16 sample = 0;
/* determine how many 6840 clocks this sample */
@ -292,13 +296,10 @@ static STREAM_UPDATE( exidy_stream_update )
/* handle timer 0 if enabled */
t = &sh6840_timer[0];
chan0_clocks = t->clocks;
if (t->cr & 0x80)
{
int clocks = (t->cr & 0x02) ? clocks_this_sample : noise_clocks_this_sample;
sh6840_apply_clock(t, clocks);
if (t->state && !(exidy_sfxctrl & 0x02))
sample += sh6840_volume[0];
}
clocks = (t->cr & 0x02) ? clocks_this_sample : noise_clocks_this_sample;
sh6840_apply_clock(t, clocks);
if (t->state && !(exidy_sfxctrl & 0x02) && (t->cr & 0x80))
sample += sh6840_volume[0];
/* generate channel 0-clocked noise if configured to do so */
if (noisy && (exidy_sfxctrl & 0x01))
@ -306,31 +307,24 @@ static STREAM_UPDATE( exidy_stream_update )
/* handle timer 1 if enabled */
t = &sh6840_timer[1];
if (t->cr & 0x80)
{
int clocks = (t->cr & 0x02) ? clocks_this_sample : noise_clocks_this_sample;
sh6840_apply_clock(t, clocks);
if (t->state)
sample += sh6840_volume[1];
}
clocks = (t->cr & 0x02) ? clocks_this_sample : noise_clocks_this_sample;
sh6840_apply_clock(t, clocks);
if (t->state && (t->cr & 0x80))
sample += sh6840_volume[1];
/* handle timer 2 if enabled */
t = &sh6840_timer[2];
if (t->cr & 0x80)
clocks = (t->cr & 0x02) ? clocks_this_sample : noise_clocks_this_sample;
/* prescale */
if (t->cr & 0x01)
{
int clocks = (t->cr & 0x02) ? clocks_this_sample : noise_clocks_this_sample;
/* prescale */
if (t->cr & 0x01)
{
clocks += t->leftovers;
t->leftovers = clocks % 8;
clocks /= 8;
}
sh6840_apply_clock(t, clocks);
if (t->state)
sample += sh6840_volume[2];
clocks += t->leftovers;
t->leftovers = clocks % 8;
clocks /= 8;
}
sh6840_apply_clock(t, clocks);
if (t->state && (t->cr & 0x80))
sample += sh6840_volume[2];
}
/* music (if present) */
@ -410,7 +404,8 @@ static DEVICE_RESET( common_sh_reset )
{
/* 6840 */
memset(sh6840_timer, 0, sizeof(sh6840_timer));
sh6840_MSB = 0;
sh6840_MSB_latch = 0;
sh6840_LSB_latch = 0;
sh6840_volume[0] = 0;
sh6840_volume[1] = 0;
sh6840_volume[2] = 0;
@ -606,8 +601,26 @@ static READ8_HANDLER( exidy_sh8253_r )
READ8_HANDLER( exidy_sh6840_r )
{
logerror("%04X:exidy_sh6840_r - unexpected read\n", cpu_get_pc(space->cpu));
return 0;
/* force an update of the stream */
stream_update(exidy_stream);
switch (offset)
{
/* offset 0: Motorola datasheet says it isn't used, Hitachi datasheet says it reads as 0s always*/
case 0:
return 0;
/* offset 1 reads the status register: bits 2 1 0 correspond to ints on channels 2,1,0, and bit 7 is an 'OR' of bits 2,1,0 */
case 1:
logerror("%04X:exidy_sh6840_r - unexpected read, status register is TODO!\n", cpu_get_pc(space->cpu));
return 0;
/* offsets 2,4,6 read channel 0,1,2 MSBs and latch the LSB*/
case 2: case 4: case 6:
sh6840_LSB_latch = sh6840_timer[((offset<<1)-1)].counter.b.l;
return sh6840_timer[((offset<<1)-1)].counter.b.h;
/* offsets 3,5,7 read the LSB latch*/
default: /* case 3,5,7 */
return sh6840_LSB_latch;
}
}
@ -643,7 +656,7 @@ WRITE8_HANDLER( exidy_sh6840_w )
case 2:
case 4:
case 6:
sh6840_MSB = data;
sh6840_MSB_latch = data;
break;
/* offsets 3/5/7 write to the LSB controls */
@ -653,7 +666,7 @@ WRITE8_HANDLER( exidy_sh6840_w )
{
/* latch the timer value */
int ch = (offset - 3) / 2;
sh6840_timer[ch].timer = (sh6840_MSB << 8) | (data & 0xff);
sh6840_timer[ch].timer = (sh6840_MSB_latch << 8) | (data & 0xff);
/* if CR4 is clear, the value is loaded immediately */
if (!(sh6840_timer[ch].cr & 0x10))