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Diffstat (limited to 'trunk/src/emu/sound/flt_rc.c')
-rw-r--r--trunk/src/emu/sound/flt_rc.c140
1 files changed, 140 insertions, 0 deletions
diff --git a/trunk/src/emu/sound/flt_rc.c b/trunk/src/emu/sound/flt_rc.c
new file mode 100644
index 00000000000..f17005d34c5
--- /dev/null
+++ b/trunk/src/emu/sound/flt_rc.c
@@ -0,0 +1,140 @@
+#include "emu.h"
+#include "flt_rc.h"
+
+typedef struct _filter_rc_state filter_rc_state;
+struct _filter_rc_state
+{
+ device_t *device;
+ sound_stream * stream;
+ int k;
+ int memory;
+ int type;
+};
+
+INLINE filter_rc_state *get_safe_token(device_t *device)
+{
+ assert(device != NULL);
+ assert(device->type() == FILTER_RC);
+ return (filter_rc_state *)downcast<legacy_device_base *>(device)->token();
+}
+
+const flt_rc_config flt_rc_ac_default = {FLT_RC_AC, 10000, 0, 0, CAP_U(1)};
+
+
+static STREAM_UPDATE( filter_rc_update )
+{
+ stream_sample_t *src = inputs[0];
+ stream_sample_t *dst = outputs[0];
+ filter_rc_state *info = (filter_rc_state *)param;
+ int memory = info->memory;
+
+ switch (info->type)
+ {
+ case FLT_RC_LOWPASS:
+ while (samples--)
+ {
+ memory += ((*src++ - memory) * info->k) / 0x10000;
+ *dst++ = memory;
+ }
+ break;
+ case FLT_RC_HIGHPASS:
+ case FLT_RC_AC:
+ while (samples--)
+ {
+ *dst++ = *src - memory;
+ memory += ((*src++ - memory) * info->k) / 0x10000;
+ }
+ break;
+ }
+ info->memory = memory;
+}
+
+static void set_RC_info(filter_rc_state *info, int type, double R1, double R2, double R3, double C)
+{
+ double Req;
+
+ info->type = type;
+
+ switch (info->type)
+ {
+ case FLT_RC_LOWPASS:
+ if (C == 0.0)
+ {
+ /* filter disabled */
+ info->k = 0x10000;
+ return;
+ }
+ Req = (R1 * (R2 + R3)) / (R1 + R2 + R3);
+ break;
+ case FLT_RC_HIGHPASS:
+ case FLT_RC_AC:
+ if (C == 0.0)
+ {
+ /* filter disabled */
+ info->k = 0x0;
+ info->memory = 0x0;
+ return;
+ }
+ Req = R1;
+ break;
+ default:
+ fatalerror("filter_rc_setRC: Wrong filter type %d\n", info->type);
+ }
+
+ /* Cut Frequency = 1/(2*Pi*Req*C) */
+ /* k = (1-(EXP(-TIMEDELTA/RC))) */
+ info->k = 0x10000 - 0x10000 * (exp(-1 / (Req * C) / info->device->machine().sample_rate()));
+}
+
+
+static DEVICE_START( filter_rc )
+{
+ filter_rc_state *info = get_safe_token(device);
+ const flt_rc_config *conf = (const flt_rc_config *)device->static_config();
+
+ info->device = device;
+ info->stream = device->machine().sound().stream_alloc(*device, 1, 1, device->machine().sample_rate(), info, filter_rc_update);
+ if (conf)
+ set_RC_info(info, conf->type, conf->R1, conf->R2, conf->R3, conf->C);
+ else
+ set_RC_info(info, FLT_RC_LOWPASS, 1, 1, 1, 0);
+}
+
+
+void filter_rc_set_RC(device_t *device, int type, double R1, double R2, double R3, double C)
+{
+ filter_rc_state *info = get_safe_token(device);
+
+ info->stream->update();
+
+ set_RC_info(info, type, R1, R2, R3, C);
+
+}
+
+/**************************************************************************
+ * Generic get_info
+ **************************************************************************/
+
+DEVICE_GET_INFO( filter_rc )
+{
+ switch (state)
+ {
+ /* --- the following bits of info are returned as 64-bit signed integers --- */
+ case DEVINFO_INT_TOKEN_BYTES: info->i = sizeof(filter_rc_state); break;
+
+ /* --- the following bits of info are returned as pointers to data or functions --- */
+ case DEVINFO_FCT_START: info->start = DEVICE_START_NAME( filter_rc ); break;
+ case DEVINFO_FCT_STOP: /* Nothing */ break;
+ case DEVINFO_FCT_RESET: /* Nothing */ break;
+
+ /* --- the following bits of info are returned as NULL-terminated strings --- */
+ case DEVINFO_STR_NAME: strcpy(info->s, "RC Filter"); break;
+ case DEVINFO_STR_FAMILY: strcpy(info->s, "Filters"); break;
+ case DEVINFO_STR_VERSION: strcpy(info->s, "1.0"); break;
+ case DEVINFO_STR_SOURCE_FILE: strcpy(info->s, __FILE__); break;
+ case DEVINFO_STR_CREDITS: strcpy(info->s, "Copyright Nicola Salmoria and the MAME Team"); break;
+ }
+}
+
+
+DEFINE_LEGACY_SOUND_DEVICE(FILTER_RC, filter_rc);