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Emulates the 3 vs 4-bit difference between the MC3417 and MC3418 variants

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This commit is contained in:
Zsolt Vasvari 2008-01-31 10:22:30 +00:00
parent 8ec0aae886
commit 7489a81c2f
1 changed files with 15 additions and 18 deletions
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33
src/emu/sound/hc55516.c
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@ -4,12 +4,6 @@
Copyright Nicola Salmoria and the MAME Team
Notes:
* The only difference between MC3417 and MC3418 is the number
of bits checked for the Coincidence Output. For the MC3417,
it is three bits, while for the MC3418 it is four.
This is not emulated.
*****************************************************************************/
#include "sndintrf.h"
@ -34,6 +28,7 @@ struct hc55516_data
sound_stream *channel;
int clock; /* 0 = software driven, non-0 = oscillator */
int active_clock_hi;
UINT8 shiftreg_mask;
UINT8 last_clock_state;
UINT8 digit;
@ -57,7 +52,8 @@ static void hc55516_update(void *param, stream_sample_t **inputs, stream_sample_
static void *start_common(int sndindex, int clock, const void *config, int _active_clock_hi)
static void *start_common(int sndindex, int clock, const void *config,
UINT8 _shiftreg_mask, int _active_clock_hi)
{
struct hc55516_data *chip;
@ -71,6 +67,7 @@ static void *start_common(int sndindex, int clock, const void *config, int _acti
leak = pow(exp(-1), 1.0 / (INTEGRATOR_LEAK_TC * 16000.0));
chip->clock = clock;
chip->shiftreg_mask = _shiftreg_mask;
chip->active_clock_hi = _active_clock_hi;
chip->last_clock_state = 0;
@ -94,19 +91,19 @@ static void *start_common(int sndindex, int clock, const void *config, int _acti
static void *hc55516_start(int sndindex, int clock, const void *config)
{
return start_common(sndindex, clock, config, TRUE);
return start_common(sndindex, clock, config, 0x07, TRUE);
}
static void *mc3417_start(int sndindex, int clock, const void *config)
{
return start_common(sndindex, clock, config, FALSE);
return start_common(sndindex, clock, config, 0x07, FALSE);
}
static void *mc3418_start(int sndindex, int clock, const void *config)
{
return start_common(sndindex, clock, config, FALSE);
return start_common(sndindex, clock, config, 0x0f, FALSE);
}
@ -141,25 +138,24 @@ static void process_digit(struct hc55516_data *chip)
{
double integrator = chip->integrator, temp;
/* shift the bit into the shift register */
chip->shiftreg = (chip->shiftreg << 1) | chip->digit;
/* move the estimator up or down a step based on the bit */
if (chip->digit)
{
chip->shiftreg = ((chip->shiftreg << 1) | 1) & 7;
integrator += chip->filter;
}
else
{
chip->shiftreg = (chip->shiftreg << 1) & 7;
integrator -= chip->filter;
}
/* simulate leakage */
integrator *= leak;
/* if we got all 0's or all 1's in the last n bits, bump the step up */
if (chip->shiftreg == 0 || chip->shiftreg == 7)
if (((chip->shiftreg & chip->shiftreg_mask) == 0) ||
((chip->shiftreg & chip->shiftreg_mask) == chip->shiftreg_mask))
{
chip->filter = FILTER_MAX - ((FILTER_MAX - chip->filter) * charge);
if (chip->filter > FILTER_MAX)
chip->filter = FILTER_MAX;
}
@ -168,6 +164,7 @@ static void process_digit(struct hc55516_data *chip)
else
{
chip->filter *= decay;
if (chip->filter < FILTER_MIN)
chip->filter = FILTER_MIN;
}
@ -350,7 +347,7 @@ void hc55516_get_info(void *token, UINT32 state, sndinfo *info)
/* --- the following bits of info are returned as NULL-terminated strings --- */
case SNDINFO_STR_NAME: info->s = "HC-55516"; break;
case SNDINFO_STR_CORE_FAMILY: info->s = "CVSD"; break;
case SNDINFO_STR_CORE_VERSION: info->s = "2.0"; break;
case SNDINFO_STR_CORE_VERSION: info->s = "2.1"; break;
case SNDINFO_STR_CORE_FILE: info->s = __FILE__; break;
case SNDINFO_STR_CORE_CREDITS: info->s = "Copyright Nicola Salmoria and the MAME Team"; break;
}