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beezer audio: got rid of sh6840_LFSR_oldxor, was leftover of old code. no whatsnew.

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Jonathan Gevaryahu 2011-02-05 23:40:14 +00:00
parent e6bf8f49f7
commit 259a401ad6
1 changed files with 3 additions and 8 deletions
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11
src/mame/audio/beezer.c
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@ -7,7 +7,6 @@
AKA Lord Nightmare AKA Lord Nightmare
TODO: TODO:
* get rid of sh6840_LFSR_oldxor, is leftover of old code.
* Several inexplicable things on the schematic are not handled, such as the * Several inexplicable things on the schematic are not handled, such as the
'VCO' input for 6840 channel 2 external clock whose source does not appear 'VCO' input for 6840 channel 2 external clock whose source does not appear
anywhere on the schematic, nor does it handle the 'DMOD DATA' and 'DMOD anywhere on the schematic, nor does it handle the 'DMOD DATA' and 'DMOD
@ -102,7 +101,6 @@ struct _beezer_sound_state
UINT8 sh6840_volume[4]; UINT8 sh6840_volume[4];
UINT8 sh6840_MSB_latch; UINT8 sh6840_MSB_latch;
UINT8 sh6840_LSB_latch; UINT8 sh6840_LSB_latch;
UINT8 sh6840_LFSR_oldxor;
UINT32 sh6840_LFSR; UINT32 sh6840_LFSR;
UINT32 sh6840_LFSR_clocks; UINT32 sh6840_LFSR_clocks;
UINT32 sh6840_clocks_per_sample; UINT32 sh6840_clocks_per_sample;
@ -218,7 +216,6 @@ INLINE int sh6840_update_noise(beezer_sound_state *state, int clocks)
state->sh6840_LFSR_clocks = 0; state->sh6840_LFSR_clocks = 0;
/* shift the LFSR. finally or in the result and see if we've /* shift the LFSR. finally or in the result and see if we've
* had a 0->1 transition */ * had a 0->1 transition */
state->sh6840_LFSR_oldxor = state->sh6840_LFSR&0x1;
newxor = (((state->sh6840_LFSR&0x10000)?1:0) ^ ((state->sh6840_LFSR&0x2000)?1:0))?1:0; newxor = (((state->sh6840_LFSR&0x10000)?1:0) ^ ((state->sh6840_LFSR&0x2000)?1:0))?1:0;
state->sh6840_LFSR <<= 1; state->sh6840_LFSR <<= 1;
state->sh6840_LFSR |= newxor; state->sh6840_LFSR |= newxor;
@ -248,7 +245,6 @@ static void sh6840_register_state_globals(device_t *device)
state_save_register_device_item_array(device, 0, state->sh6840_volume); state_save_register_device_item_array(device, 0, state->sh6840_volume);
state_save_register_device_item(device, 0, state->sh6840_MSB_latch); state_save_register_device_item(device, 0, state->sh6840_MSB_latch);
state_save_register_device_item(device, 0, state->sh6840_LSB_latch); state_save_register_device_item(device, 0, state->sh6840_LSB_latch);
state_save_register_device_item(device, 0, state->sh6840_LFSR_oldxor);
state_save_register_device_item(device, 0, state->sh6840_LFSR); state_save_register_device_item(device, 0, state->sh6840_LFSR);
state_save_register_device_item(device, 0, state->sh6840_LFSR_clocks); state_save_register_device_item(device, 0, state->sh6840_LFSR_clocks);
state_save_register_device_item(device, 0, state->sh6840_clock_count); state_save_register_device_item(device, 0, state->sh6840_clock_count);
@ -335,7 +331,7 @@ static STREAM_UPDATE( beezer_stream_update )
if (noisy != 0) if (noisy != 0)
{ {
noise_clocks_this_sample = sh6840_update_noise(state, t->clocks - chan1_clocks); noise_clocks_this_sample = sh6840_update_noise(state, t->clocks - chan1_clocks);
if (clocks) state->sh6840_noiselatch3 = state->sh6840_LFSR_oldxor; if (clocks) state->sh6840_noiselatch3 = (state->sh6840_LFSR&0x1);
} }
/* handle timer 2 if enabled */ /* handle timer 2 if enabled */
@ -423,7 +419,6 @@ static DEVICE_RESET( common_sh_reset )
state->sh6840_noiselatch3 = 0; state->sh6840_noiselatch3 = 0;
/* LFSR */ /* LFSR */
state->sh6840_LFSR_oldxor = 0;
state->sh6840_LFSR = 0xffffffff; state->sh6840_LFSR = 0xffffffff;
state->sh6840_LFSR_clocks = 0; state->sh6840_LFSR_clocks = 0;
} }
@ -493,7 +488,7 @@ WRITE8_DEVICE_HANDLER( beezer_timer1_w )
state->sh6840_latchwrite = data&0x80; state->sh6840_latchwrite = data&0x80;
if ((!state->sh6840_latchwriteold) && (state->sh6840_latchwrite)) // rising edge if ((!state->sh6840_latchwriteold) && (state->sh6840_latchwrite)) // rising edge
{ {
state->sh6840_noiselatch1 = state->sh6840_LFSR_oldxor; state->sh6840_noiselatch1 = (state->sh6840_LFSR&0x1);
} }
} }
@ -503,7 +498,7 @@ READ8_DEVICE_HANDLER( beezer_noise_r )
/* force an update of the stream */ /* force an update of the stream */
state->stream->update(); state->stream->update();
return state->sh6840_LFSR_oldxor; return (state->sh6840_LFSR&0x1);
} }
WRITE8_DEVICE_HANDLER( beezer_sh6840_w ) WRITE8_DEVICE_HANDLER( beezer_sh6840_w )