Got rid of R->OldNoise since it causes problems for gamegear/sms. Changed noise taps accordingly. Redid change to gamegear/sms for XOR vs XNOR, now verified by Justin Kerk. Verified gamegear noise taps thanks to sample provided by Justin Kerk.
Add stereo sound support to sn76496.c for gamegear. [Lord Nightmare, Justin Kerk]
This commit is contained in:
Jonathan Gevaryahu
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c3ea836b07
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3dbbc11f0d
@ -30,6 +30,7 @@
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The register, connected to a z80 port, means:
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for bits 7 6 5 4 3 2 1 0
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L3 L2 L1 L0 R3 R2 R1 R0
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Noise is an XOR function, and audio output is negated before being output.
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** NCR7496 (as used on the Tandy 1000) is similar to the SN76489 but with a
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different noise LFSR patttern: taps on bits A and E, output on E
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It uses a 15-bit ring buffer for periodic noise/arbitrary duty cycle.
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@ -62,11 +63,14 @@
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Fix screeching in regulus: When summing together four equal channels, the
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size of the max amplitude per channel should be 1/4 of the max range, not
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1/3. Added NCR7496.
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18/11/2009 : Lord Nightmare
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Modify Init functions to support negating the audio output. The gamegear
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psg does this. Change gamegear and sega psgs to use XOR rather than XNOR
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based on testing. Got rid of R->OldNoise and fixed taps accordingly.
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Added stereo support for game gear.
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TODO: * Implement a function for setting stereo regs for the game gear.
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Requires making the core support both mono and stereo, and have
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a select register which determines which channels go where.
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* Implement the TMS9919 which is an earlier version, possibly
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TODO: * Implement the TMS9919 which is an earlier version, possibly
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lacking the /8 clock divider, of the SN76489, and hence would
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have a max clock of 500Khz and 4 clocks per sample, as opposed to
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max of 4Mhz and 32 clocks per sample on the SN76489A.
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@ -74,8 +78,6 @@
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to be 'sanitized' first. Also is stereo, similar to game gear.
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* Test the NCR7496; Smspower says the whitenoise taps are A and E,
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but this needs verification on real hardware.
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* Test the SMS PSG/Gamegear PSG to see whether it uses XOR or XNOR
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taps. (17/11/2009: this seems to be XNOR? Need a better sample.)
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* Factor out common code so that the SAA1099 can share some code.
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***************************************************************************/
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@ -101,9 +103,11 @@ struct _sn76496_state
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INT32 FeedbackMask; /* mask for feedback */
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INT32 WhitenoiseTaps; /* mask for white noise taps */
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INT32 FeedbackInvert; /* feedback invert flag (xor vs xnor) */
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INT32 Negate; /* output negate flag */
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INT32 Stereo; /* whether we're dealing with stereo or not */
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INT32 StereoMask; /* the stereo output mask */
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INT32 Period[4]; /* Length of 1/2 of waveform */
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INT32 Count[4]; /* Position within the waveform */
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INT32 OldNoise; /* 1 bit output of the PREVIOUS noise output */
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INT32 Output[4]; /* 1-bit output of each channel, pre-volume */
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INT32 CyclestoREADY;/* number of cycles until the READY line goes active */
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};
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@ -132,6 +136,14 @@ READ8_DEVICE_HANDLER( sn76496_ready_r )
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return (R->CyclestoREADY? 0 : 1);
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}
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WRITE8_DEVICE_HANDLER( sn76496_stereo_w )
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{
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sn76496_state *R = get_safe_token(device);
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stream_update(R->Channel);
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if (R->Stereo) R->StereoMask = data;
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else fatalerror("Call to stereo write with mono chip!\n");
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}
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WRITE8_DEVICE_HANDLER( sn76496_w )
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{
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sn76496_state *R = get_safe_token(device);
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@ -192,9 +204,7 @@ WRITE8_DEVICE_HANDLER( sn76496_w )
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R->Period[3] = ((n&3) == 3) ? 2 * R->Period[2] : (1 << (5+(n&3)));
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/* Reset noise shifter */
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R->RNG = R->FeedbackMask;
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R->OldNoise = 0;
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R->Output[3] = R->OldNoise;
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R->OldNoise = R->RNG & 1;
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R->Output[3] = R->RNG & 1;
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}
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break;
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}
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@ -204,13 +214,14 @@ static STREAM_UPDATE( SN76496Update )
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{
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int i;
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sn76496_state *R = (sn76496_state *)param;
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stream_sample_t *buffer = outputs[0];
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stream_sample_t *lbuffer = outputs[0];
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stream_sample_t *rbuffer = outputs[1];
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while (samples > 0)
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{
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// clock chip once
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INT16 out;
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INT16 out = 0;
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INT16 out2 = 0;
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/* decrement Cycles to READY by one */
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if (R->CyclestoREADY >0) R->CyclestoREADY--;
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@ -254,8 +265,7 @@ static STREAM_UPDATE( SN76496Update )
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R->RNG >>= 1;
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}
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}
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R->Output[3] = R->OldNoise;
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R->OldNoise = R->RNG & 1;
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R->Output[3] = R->RNG & 1;
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R->Count[3] = R->Period[3];
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}
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/* //bipolar output, doesn't seem to work right with sonic 2 on gamegear at least
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@ -264,13 +274,30 @@ static STREAM_UPDATE( SN76496Update )
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+(R->Output[2]?R->Volume[2]:(0-R->Volume[2]))
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+(R->Output[3]?R->Volume[3]:(0-R->Volume[3]));
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*/
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out = (R->Output[0]?R->Volume[0]:0)
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+(R->Output[1]?R->Volume[1]:0)
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+(R->Output[2]?R->Volume[2]:0)
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+(R->Output[3]?R->Volume[3]:0);
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if (R->Stereo)
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{
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out = (((R->StereoMask&0x10)&&R->Output[0])?R->Volume[0]:0)
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+ (((R->StereoMask&0x20)&&R->Output[1])?R->Volume[1]:0)
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+ (((R->StereoMask&0x40)&&R->Output[2])?R->Volume[2]:0)
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+ (((R->StereoMask&0x80)&&R->Output[3])?R->Volume[3]:0);
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out2 = (((R->StereoMask&0x1)&&R->Output[0])?R->Volume[0]:0)
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+ (((R->StereoMask&0x2)&&R->Output[1])?R->Volume[1]:0)
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+ (((R->StereoMask&0x4)&&R->Output[2])?R->Volume[2]:0)
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+ (((R->StereoMask&0x8)&&R->Output[3])?R->Volume[3]:0);
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}
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else
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{
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out = (R->Output[0]?R->Volume[0]:0)
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+(R->Output[1]?R->Volume[1]:0)
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+(R->Output[2]?R->Volume[2]:0)
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+(R->Output[3]?R->Volume[3]:0);
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}
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*(buffer++) = out;
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if(R->Negate) { out = -out; out2 = -out2; }
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*(lbuffer++) = out;
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if (R->Stereo) *(rbuffer++) = out2;
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samples--;
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}
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}
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@ -294,7 +321,7 @@ static void SN76496_set_gain(sn76496_state *R,int gain)
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for (i = 0;i < 15;i++)
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{
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/* limit volume to avoid clipping */
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if (out > MAX_OUTPUT / 3) R->VolTable[i] = MAX_OUTPUT / 3;
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if (out > MAX_OUTPUT / 4) R->VolTable[i] = MAX_OUTPUT / 4;
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else R->VolTable[i] = out;
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out /= 1.258925412; /* = 10 ^ (2/20) = 2dB */
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@ -304,12 +331,12 @@ static void SN76496_set_gain(sn76496_state *R,int gain)
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static int SN76496_init(const device_config *device, sn76496_state *R)
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static int SN76496_init(const device_config *device, sn76496_state *R, int stereo)
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{
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int sample_rate = device->clock/16;
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int i;
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R->Channel = stream_create(device,0,1,sample_rate,R,SN76496Update);
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R->Channel = stream_create(device,0,(stereo?2:1),sample_rate,R,SN76496Update);
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for (i = 0;i < 4;i++) R->Volume[i] = 0;
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@ -330,27 +357,30 @@ static int SN76496_init(const device_config *device, sn76496_state *R)
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R->WhitenoiseTaps = 0x03; /* mask for white noise taps */
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R->FeedbackInvert = 0; /* feedback invert flag */
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R->CyclestoREADY = 1; /* assume ready is not active immediately on init. is this correct?*/
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R->Negate = 0; /* channels are not negated */
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R->Stereo = stereo; /* depends on init */
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R->StereoMask = 0xFF; /* all channels enabled */
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R->RNG = R->FeedbackMask;
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R->OldNoise = 0;
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R->Output[3] = R->OldNoise;
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R->OldNoise = R->RNG & 1;
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R->Output[3] = R->RNG & 1;
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return 0;
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}
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static void generic_start(const device_config *device, int feedbackmask, int noisetaps, int feedbackinvert)
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static void generic_start(const device_config *device, int feedbackmask, int noisetaps, int feedbackinvert, int negate, int stereo)
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{
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sn76496_state *chip = get_safe_token(device);
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if (SN76496_init(device,chip) != 0)
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if (SN76496_init(device,chip,stereo) != 0)
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fatalerror("Error creating SN76496 chip");
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SN76496_set_gain(chip, 0);
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chip->FeedbackMask = feedbackmask;
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chip->WhitenoiseTaps = noisetaps;
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chip->FeedbackInvert = feedbackinvert;
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chip->Negate = negate;
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chip->Stereo = stereo;
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state_save_register_device_item_array(device, 0, chip->VolTable);
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state_save_register_device_item_array(device, 0, chip->Register);
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@ -360,52 +390,55 @@ static void generic_start(const device_config *device, int feedbackmask, int noi
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state_save_register_device_item(device, 0, chip->FeedbackMask);
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state_save_register_device_item(device, 0, chip->WhitenoiseTaps);
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state_save_register_device_item(device, 0, chip->FeedbackInvert);
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state_save_register_device_item(device, 0, chip->Negate);
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state_save_register_device_item(device, 0, chip->Stereo);
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state_save_register_device_item(device, 0, chip->StereoMask);
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state_save_register_device_item_array(device, 0, chip->Period);
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state_save_register_device_item_array(device, 0, chip->Count);
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state_save_register_device_item(device, 0, chip->OldNoise);
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state_save_register_device_item_array(device, 0, chip->Output);
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state_save_register_device_item(device, 0, chip->CyclestoREADY);
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}
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// function parameters: device, feedback destination tap, feedback source taps, xor(false)/xnor(true), normal(false)/invert(true), mono(false)/stereo(true)
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static DEVICE_START( sn76489 )
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{
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generic_start(device, 0x4000, 0x03, FALSE); // todo: verify; assumed to be the same as sn94624
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generic_start(device, 0x8000, 0x06, FALSE, FALSE, FALSE); // todo: verify; assumed to be the same as sn94624
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}
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static DEVICE_START( sn76489a )
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{
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generic_start(device, 0x8000, 0x06, TRUE); // verified by plgdavid
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generic_start(device, 0x10000, 0x0C, TRUE, FALSE, FALSE); // verified by plgdavid
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}
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static DEVICE_START( sn76494 )
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{
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generic_start(device, 0x8000, 0x06, TRUE); // todo: verify; assumed to be the same as sn76489a
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generic_start(device, 0x10000, 0x0C, TRUE, FALSE, FALSE); // todo: verify; assumed to be the same as sn76489a
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}
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static DEVICE_START( sn76496 )
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{
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generic_start(device, 0x8000, 0x06, TRUE); // todo: verify; assumed to be the same as sn76489a
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generic_start(device, 0x10000, 0x0C, TRUE, FALSE, FALSE); // todo: verify; assumed to be the same as sn76489a
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}
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static DEVICE_START( sn94624 )
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{
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generic_start(device, 0x4000, 0x03, FALSE); // verified by plgdavid
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generic_start(device, 0x10000, 0x0C, FALSE, FALSE, FALSE); // verified by plgdavid
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}
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static DEVICE_START( ncr7496 )
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{
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generic_start(device, 0x4000, 0x11, FALSE); // todo: verify; from smspower wiki
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generic_start(device, 0x8000, 0x22, FALSE, FALSE, FALSE); // todo: verify; from smspower wiki
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}
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static DEVICE_START( gamegear )
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{
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generic_start(device, 0x8000, 0x09, TRUE); // semi-verified by Lord Nightmare, need better sample
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generic_start(device, 0x8000, 0x09, FALSE, TRUE, TRUE); // Verified by Justin Kerk
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}
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static DEVICE_START( smsiii )
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{
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generic_start(device, 0x8000, 0x09, TRUE); // todo: verify; from smspower wiki, assumed to have same invert as gamegear
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generic_start(device, 0x8000, 0x09, FALSE, TRUE, FALSE); // todo: verify; from smspower wiki, assumed to have same invert as gamegear
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}
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@ -5,6 +5,7 @@
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READ8_DEVICE_HANDLER( sn76496_ready_r );
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WRITE8_DEVICE_HANDLER( sn76496_w );
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WRITE8_DEVICE_HANDLER( sn76496_stereo_w );
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DEVICE_GET_INFO( sn76496 );
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DEVICE_GET_INFO( sn76489 );
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