// license:BSD-3-Clause // copyright-holders:Nathan Woods, Raphael Nabet, R. Belmont /*************************************************************************** mac.c Sound handler ****************************************************************************/ #include "emu.h" #include "sound/asc.h" #include "includes/mac.h" #include "machine/ram.h" /*************************************************************************** MACROS / CONSTANTS ***************************************************************************/ #define MAC_MAIN_SND_BUF_OFFSET 0x0300 #define MAC_ALT_SND_BUF_OFFSET 0x5F00 #define MAC_SND_BUF_SIZE 370 /* total number of scan lines */ #define MAC_SAMPLE_RATE ( MAC_SND_BUF_SIZE * 60 /*22255*/ ) /* scan line rate, should be 22254.5 Hz */ /* intermediate buffer */ #define SND_CACHE_SIZE 128 const device_type MAC_SOUND = &device_creator; mac_sound_device::mac_sound_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : device_t(mconfig, MAC_SOUND, "Mac Audio Custom", tag, owner, clock, "mac_sound", __FILE__), device_sound_interface(mconfig, *this), m_sample_enable(0), m_mac_snd_buf_ptr(NULL), m_snd_cache_len(0), m_snd_cache_head(0), m_snd_cache_tail(0), m_indexx(0) { } //------------------------------------------------- // device_config_complete - perform any // operations now that the configuration is // complete //------------------------------------------------- void mac_sound_device::device_config_complete() { } //------------------------------------------------- // device_start - device-specific startup //------------------------------------------------- void mac_sound_device::device_start() { mac_state *mac = machine().driver_data(); m_snd_cache = auto_alloc_array_clear(machine(), UINT8, SND_CACHE_SIZE); m_mac_stream = machine().sound().stream_alloc(*this, 0, 1, MAC_SAMPLE_RATE); m_ram = machine().device(RAM_TAG); m_mac_model = mac->m_model; save_pointer(NAME(m_snd_cache), SND_CACHE_SIZE); save_item(NAME(m_sample_enable)); save_item(NAME(m_snd_cache_len)); save_item(NAME(m_snd_cache_head)); save_item(NAME(m_snd_cache_tail)); save_item(NAME(m_indexx)); } //------------------------------------------------- // sound_stream_update - handle a stream update //------------------------------------------------- void mac_sound_device::sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples) { INT16 last_val = 0; stream_sample_t *buffer = outputs[0]; if ((m_mac_model == MODEL_MAC_PORTABLE) || (m_mac_model == MODEL_MAC_PB100)) { memset(buffer, 0, samples * sizeof(*buffer)); return; } /* if we're not enabled, just fill with 0 */ if (machine().sample_rate() == 0) { memset(buffer, 0, samples * sizeof(*buffer)); return; } /* fill in the sample */ while (samples && m_snd_cache_len) { *buffer++ = last_val = ((m_snd_cache[m_snd_cache_head] << 8) ^ 0x8000) & 0xff00; m_snd_cache_head++; m_snd_cache_head %= SND_CACHE_SIZE; m_snd_cache_len--; samples--; } while (samples--) { /* should never happen */ *buffer++ = last_val; } } /*************************************************************************** IMPLEMENTATION ***************************************************************************/ // Set the sound enable flag (VIA port line) void mac_sound_device::enable_sound(int on) { m_sample_enable = on; } // Set the current sound buffer (one VIA port line) void mac_sound_device::set_sound_buffer(int buffer) { if (buffer) m_mac_snd_buf_ptr = (UINT16 *) (m_ram->pointer() + m_ram->size() - MAC_MAIN_SND_BUF_OFFSET); else m_mac_snd_buf_ptr = (UINT16 *) (m_ram->pointer() + m_ram->size() - MAC_ALT_SND_BUF_OFFSET); } // Set the current sound volume (3 VIA port line) void mac_sound_device::set_volume(int volume) { m_mac_stream->update(); volume = (100 / 7) * volume; m_mac_stream->set_output_gain(0, volume / 100.0); } // Fetch one byte from sound buffer and put it to sound output (called every scanline) void mac_sound_device::sh_updatebuffer() { UINT16 *base = m_mac_snd_buf_ptr; m_indexx++; m_indexx %= 370; if (m_snd_cache_len >= SND_CACHE_SIZE) { /* clear buffer */ m_mac_stream->update(); } if (m_snd_cache_len >= SND_CACHE_SIZE) /* should never happen */ return; m_snd_cache[m_snd_cache_tail] = m_sample_enable ? (base[m_indexx] >> 8) & 0xff : 0; m_snd_cache_tail++; m_snd_cache_tail %= SND_CACHE_SIZE; m_snd_cache_len++; }