diff options
Diffstat (limited to 'trunk/src/emu/sound/okim6258.c')
-rw-r--r-- | trunk/src/emu/sound/okim6258.c | 384 |
1 files changed, 384 insertions, 0 deletions
diff --git a/trunk/src/emu/sound/okim6258.c b/trunk/src/emu/sound/okim6258.c new file mode 100644 index 00000000000..aa939cc3fe2 --- /dev/null +++ b/trunk/src/emu/sound/okim6258.c @@ -0,0 +1,384 @@ +/********************************************************************************************** + * + * OKI MSM6258 ADPCM + * + * TODO: + * 3-bit ADPCM support + * Recording? + * + **********************************************************************************************/ + + +#include "emu.h" +#include "okim6258.h" + +#define COMMAND_STOP (1 << 0) +#define COMMAND_PLAY (1 << 1) +#define COMMAND_RECORD (1 << 2) + +#define STATUS_PLAYING (1 << 1) +#define STATUS_RECORDING (1 << 2) + +static const int dividers[4] = { 1024, 768, 512, 512 }; + +typedef struct _okim6258_state okim6258_state; +struct _okim6258_state +{ + UINT8 status; + + UINT32 master_clock; /* master clock frequency */ + UINT32 divider; /* master clock divider */ + UINT8 adpcm_type; /* 3/4 bit ADPCM select */ + UINT8 data_in; /* ADPCM data-in register */ + UINT8 nibble_shift; /* nibble select */ + sound_stream *stream; /* which stream are we playing on? */ + + UINT8 output_bits; + + INT32 signal; + INT32 step; +}; + +/* step size index shift table */ +static const int index_shift[8] = { -1, -1, -1, -1, 2, 4, 6, 8 }; + +/* lookup table for the precomputed difference */ +static int diff_lookup[49*16]; + +/* tables computed? */ +static int tables_computed = 0; + +INLINE okim6258_state *get_safe_token(device_t *device) +{ + assert(device != NULL); + assert(device->type() == OKIM6258); + return (okim6258_state *)downcast<legacy_device_base *>(device)->token(); +} + +/********************************************************************************************** + + compute_tables -- compute the difference tables + +***********************************************************************************************/ + +static void compute_tables(void) +{ + /* nibble to bit map */ + static const int nbl2bit[16][4] = + { + { 1, 0, 0, 0}, { 1, 0, 0, 1}, { 1, 0, 1, 0}, { 1, 0, 1, 1}, + { 1, 1, 0, 0}, { 1, 1, 0, 1}, { 1, 1, 1, 0}, { 1, 1, 1, 1}, + {-1, 0, 0, 0}, {-1, 0, 0, 1}, {-1, 0, 1, 0}, {-1, 0, 1, 1}, + {-1, 1, 0, 0}, {-1, 1, 0, 1}, {-1, 1, 1, 0}, {-1, 1, 1, 1} + }; + + int step, nib; + + /* loop over all possible steps */ + for (step = 0; step <= 48; step++) + { + /* compute the step value */ + int stepval = floor(16.0 * pow(11.0 / 10.0, (double)step)); + + /* loop over all nibbles and compute the difference */ + for (nib = 0; nib < 16; nib++) + { + diff_lookup[step*16 + nib] = nbl2bit[nib][0] * + (stepval * nbl2bit[nib][1] + + stepval/2 * nbl2bit[nib][2] + + stepval/4 * nbl2bit[nib][3] + + stepval/8); + } + } + + tables_computed = 1; +} + + +static INT16 clock_adpcm(okim6258_state *chip, UINT8 nibble) +{ + INT32 max = (1 << (chip->output_bits - 1)) - 1; + INT32 min = -(1 << (chip->output_bits - 1)); + + chip->signal += diff_lookup[chip->step * 16 + (nibble & 15)]; + + /* clamp to the maximum */ + if (chip->signal > max) + chip->signal = max; + else if (chip->signal < min) + chip->signal = min; + + /* adjust the step size and clamp */ + chip->step += index_shift[nibble & 7]; + if (chip->step > 48) + chip->step = 48; + else if (chip->step < 0) + chip->step = 0; + + /* return the signal scaled up to 32767 */ + return chip->signal << 4; +} + +/********************************************************************************************** + + okim6258_update -- update the sound chip so that it is in sync with CPU execution + +***********************************************************************************************/ + +static STREAM_UPDATE( okim6258_update ) +{ + okim6258_state *chip = (okim6258_state *)param; + stream_sample_t *buffer = outputs[0]; + + memset(outputs[0], 0, samples * sizeof(*outputs[0])); + + if (chip->status & STATUS_PLAYING) + { + int nibble_shift = chip->nibble_shift; + + while (samples) + { + /* Compute the new amplitude and update the current step */ + int nibble = (chip->data_in >> nibble_shift) & 0xf; + + /* Output to the buffer */ + INT16 sample = clock_adpcm(chip, nibble); + + nibble_shift ^= 4; + + *buffer++ = sample; + samples--; + } + + /* Update the parameters */ + chip->nibble_shift = nibble_shift; + } + else + { + /* Fill with 0 */ + while (samples--) + *buffer++ = 0; + } +} + + + +/********************************************************************************************** + + state save support for MAME + +***********************************************************************************************/ + +static void okim6258_state_save_register(okim6258_state *info, device_t *device) +{ + device->save_item(NAME(info->status)); + device->save_item(NAME(info->master_clock)); + device->save_item(NAME(info->divider)); + device->save_item(NAME(info->data_in)); + device->save_item(NAME(info->nibble_shift)); + device->save_item(NAME(info->signal)); + device->save_item(NAME(info->step)); +} + + +/********************************************************************************************** + + OKIM6258_start -- start emulation of an OKIM6258-compatible chip + +***********************************************************************************************/ + +static DEVICE_START( okim6258 ) +{ + const okim6258_interface *intf = (const okim6258_interface *)device->static_config(); + okim6258_state *info = get_safe_token(device); + + compute_tables(); + + info->master_clock = device->clock(); + info->adpcm_type = intf->adpcm_type; + + /* D/A precision is 10-bits but 12-bit data can be output serially to an external DAC */ + info->output_bits = intf->output_12bits ? 12 : 10; + info->divider = dividers[intf->divider]; + + info->stream = device->machine().sound().stream_alloc(*device, 0, 1, device->clock()/info->divider, info, okim6258_update); + + info->signal = -2; + info->step = 0; + + okim6258_state_save_register(info, device); +} + + +/********************************************************************************************** + + OKIM6258_stop -- stop emulation of an OKIM6258-compatible chip + +***********************************************************************************************/ + +static DEVICE_RESET( okim6258 ) +{ + okim6258_state *info = get_safe_token(device); + + info->stream->update(); + + info->signal = -2; + info->step = 0; + info->status = 0; +} + + +/********************************************************************************************** + + okim6258_set_divider -- set the master clock divider + +***********************************************************************************************/ + +void okim6258_set_divider(device_t *device, int val) +{ + okim6258_state *info = get_safe_token(device); + int divider = dividers[val]; + + info->divider = dividers[val]; + info->stream->set_sample_rate(info->master_clock / divider); +} + + +/********************************************************************************************** + + okim6258_set_clock -- set the master clock + +***********************************************************************************************/ + +void okim6258_set_clock(device_t *device, int val) +{ + okim6258_state *info = get_safe_token(device); + + info->master_clock = val; + info->stream->set_sample_rate(info->master_clock / info->divider); +} + + +/********************************************************************************************** + + okim6258_get_vclk -- get the VCLK/sampling frequency + +***********************************************************************************************/ + +int okim6258_get_vclk(device_t *device) +{ + okim6258_state *info = get_safe_token(device); + + return (info->master_clock / info->divider); +} + + +/********************************************************************************************** + + okim6258_status_r -- read the status port of an OKIM6258-compatible chip + +***********************************************************************************************/ + +READ8_DEVICE_HANDLER( okim6258_status_r ) +{ + okim6258_state *info = get_safe_token(device); + + info->stream->update(); + + return (info->status & STATUS_PLAYING) ? 0x00 : 0x80; +} + + +/********************************************************************************************** + + okim6258_data_w -- write to the control port of an OKIM6258-compatible chip + +***********************************************************************************************/ +WRITE8_DEVICE_HANDLER( okim6258_data_w ) +{ + okim6258_state *info = get_safe_token(device); + + /* update the stream */ + info->stream->update(); + + info->data_in = data; + info->nibble_shift = 0; +} + + +/********************************************************************************************** + + okim6258_ctrl_w -- write to the control port of an OKIM6258-compatible chip + +***********************************************************************************************/ + +WRITE8_DEVICE_HANDLER( okim6258_ctrl_w ) +{ + okim6258_state *info = get_safe_token(device); + + info->stream->update(); + + if (data & COMMAND_STOP) + { + info->status &= ~(STATUS_PLAYING | STATUS_RECORDING); + return; + } + + if (data & COMMAND_PLAY) + { + if (!(info->status & STATUS_PLAYING)) + { + info->status |= STATUS_PLAYING; + + /* Also reset the ADPCM parameters */ + info->signal = -2; + info->step = 0; + info->nibble_shift = 0; + } + } + else + { + info->status &= ~STATUS_PLAYING; + } + + if (data & COMMAND_RECORD) + { + logerror("M6258: Record enabled\n"); + info->status |= STATUS_RECORDING; + } + else + { + info->status &= ~STATUS_RECORDING; + } +} + + + + +/************************************************************************** + * Generic get_info + **************************************************************************/ + +DEVICE_GET_INFO( okim6258 ) +{ + switch (state) + { + /* --- the following bits of info are returned as 64-bit signed integers --- */ + case DEVINFO_INT_TOKEN_BYTES: info->i = sizeof(okim6258_state); break; + + /* --- the following bits of info are returned as pointers to data or functions --- */ + case DEVINFO_FCT_START: info->start = DEVICE_START_NAME(okim6258); break; + case DEVINFO_FCT_STOP: /* nothing */ break; + case DEVINFO_FCT_RESET: info->reset = DEVICE_RESET_NAME(okim6258); break; + + /* --- the following bits of info are returned as NULL-terminated strings --- */ + case DEVINFO_STR_NAME: strcpy(info->s, "OKI6258"); break; + case DEVINFO_STR_FAMILY: strcpy(info->s, "OKI ADPCM"); 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(OKIM6258, okim6258); |