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/*********************************************************/
/* SEGA 16ch 8bit PCM */
/*********************************************************/
#include "emu.h"
#include "segapcm.h"
typedef struct _segapcm_state segapcm_state;
struct _segapcm_state
{
UINT8 *ram;
UINT8 low[16];
const UINT8 *rom;
int bankshift;
int bankmask;
int rgnmask;
sound_stream * stream;
};
INLINE segapcm_state *get_safe_token(device_t *device)
{
assert(device != NULL);
assert(device->type() == SEGAPCM);
return (segapcm_state *)downcast<segapcm_device *>(device)->token();
}
static STREAM_UPDATE( SEGAPCM_update )
{
segapcm_state *spcm = (segapcm_state *)param;
int rgnmask = spcm->rgnmask;
int ch;
/* clear the buffers */
memset(outputs[0], 0, samples*sizeof(*outputs[0]));
memset(outputs[1], 0, samples*sizeof(*outputs[1]));
// reg function
// ------------------------------------------------
// 0x00 ?
// 0x01 ?
// 0x02 volume left
// 0x03 volume right
// 0x04 loop address (08-15)
// 0x05 loop address (16-23)
// 0x06 end address
// 0x07 address delta
// 0x80 ?
// 0x81 ?
// 0x82 ?
// 0x83 ?
// 0x84 current address (08-15), 00-07 is internal?
// 0x85 current address (16-23)
// 0x86 bit 0: channel disable?
// bit 1: loop disable
// other bits: bank
// 0x87 ?
/* loop over channels */
for (ch = 0; ch < 16; ch++)
{
UINT8 *regs = spcm->ram+8*ch;
/* only process active channels */
if (!(regs[0x86]&1))
{
const UINT8 *rom = spcm->rom + ((regs[0x86] & spcm->bankmask) << spcm->bankshift);
UINT32 addr = (regs[0x85] << 16) | (regs[0x84] << 8) | spcm->low[ch];
UINT32 loop = (regs[0x05] << 16) | (regs[0x04] << 8);
UINT8 end = regs[6] + 1;
int i;
/* loop over samples on this channel */
for (i = 0; i < samples; i++)
{
INT8 v = 0;
/* handle looping if we've hit the end */
if ((addr >> 16) == end)
{
if (regs[0x86] & 2)
{
regs[0x86] |= 1;
break;
}
else addr = loop;
}
/* fetch the sample */
v = rom[(addr >> 8) & rgnmask] - 0x80;
/* apply panning and advance */
outputs[0][i] += v * regs[2];
outputs[1][i] += v * regs[3];
addr = (addr + regs[7]) & 0xffffff;
}
/* store back the updated address */
regs[0x84] = addr >> 8;
regs[0x85] = addr >> 16;
spcm->low[ch] = regs[0x86] & 1 ? 0 : addr;
}
}
}
static DEVICE_START( segapcm )
{
const sega_pcm_interface *intf = (const sega_pcm_interface *)device->static_config();
int mask, rom_mask, len;
segapcm_state *spcm = get_safe_token(device);
spcm->rom = *device->region();
spcm->ram = auto_alloc_array(device->machine(), UINT8, 0x800);
memset(spcm->ram, 0xff, 0x800);
spcm->bankshift = (UINT8)(intf->bank);
mask = intf->bank >> 16;
if(!mask)
mask = BANK_MASK7>>16;
len = device->region()->bytes();
spcm->rgnmask = len - 1;
for(rom_mask = 1; rom_mask < len; rom_mask *= 2);
rom_mask--;
spcm->bankmask = mask & (rom_mask >> spcm->bankshift);
spcm->stream = device->machine().sound().stream_alloc(*device, 0, 2, device->clock() / 128, spcm, SEGAPCM_update);
device->save_item(NAME(spcm->low));
device->save_pointer(NAME(spcm->ram), 0x800);
}
WRITE8_DEVICE_HANDLER( sega_pcm_w )
{
segapcm_state *spcm = get_safe_token(device);
spcm->stream->update();
spcm->ram[offset & 0x07ff] = data;
}
READ8_DEVICE_HANDLER( sega_pcm_r )
{
segapcm_state *spcm = get_safe_token(device);
spcm->stream->update();
return spcm->ram[offset & 0x07ff];
}
const device_type SEGAPCM = &device_creator<segapcm_device>;
segapcm_device::segapcm_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
: device_t(mconfig, SEGAPCM, "Sega PCM", tag, owner, clock),
device_sound_interface(mconfig, *this)
{
m_token = global_alloc_array_clear(UINT8, sizeof(segapcm_state));
}
//-------------------------------------------------
// device_config_complete - perform any
// operations now that the configuration is
// complete
//-------------------------------------------------
void segapcm_device::device_config_complete()
{
}
//-------------------------------------------------
// device_start - device-specific startup
//-------------------------------------------------
void segapcm_device::device_start()
{
DEVICE_START_NAME( segapcm )(this);
}
//-------------------------------------------------
// sound_stream_update - handle a stream update
//-------------------------------------------------
void segapcm_device::sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples)
{
// should never get here
fatalerror("sound_stream_update called; not applicable to legacy sound devices\n");
}
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