152 lines
3.9 KiB
C++
152 lines
3.9 KiB
C++
// license:BSD-3-Clause
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// copyright-holders:Hiromitsu Shioya, Olivier Galibert
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/*********************************************************/
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/* SEGA 16ch 8bit PCM */
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/*********************************************************/
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#include <string.h>
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#include "segapcm.h"
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//-------------------------------------------------
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// segapcm_device - constructor
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//-------------------------------------------------
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segapcm_device::segapcm_device()
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: m_bankshift(12)
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, m_bankmask(0x70)
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{
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memset(m_muted,0,16*sizeof(bool));
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}
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//-------------------------------------------------
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// device_start - device-specific startup
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//-------------------------------------------------
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void segapcm_device::device_start()
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{
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memset(m_ram,255,0x800);
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memset(m_low,0,16);
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memset(lastOut,0,16*2*sizeof(short));
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}
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//-------------------------------------------------
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// sound_stream_update - handle a stream update
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//-------------------------------------------------
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void segapcm_device::sound_stream_update(int* outputs)
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{
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/* clear the buffers */
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outputs[0]=0;
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outputs[1]=0;
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// reg function
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// ------------------------------------------------
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// 0x00 ?
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// 0x01 ?
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// 0x02 volume left
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// 0x03 volume right
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// 0x04 loop address (08-15)
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// 0x05 loop address (16-23)
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// 0x06 end address
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// 0x07 address delta
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// 0x80 ?
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// 0x81 ?
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// 0x82 ?
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// 0x83 ?
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// 0x84 current address (08-15), 00-07 is internal?
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// 0x85 current address (16-23)
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// 0x86 bit 0: channel disable?
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// bit 1: loop disable
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// other bits: bank
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// 0x87 ?
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/* loop over channels */
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for (int ch = 0; ch < 16; ch++)
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{
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uint8_t *regs = &m_ram[8*ch];
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/* only process active channels */
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if (!(regs[0x86]&1))
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{
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int offset = (regs[0x86] & m_bankmask) << m_bankshift;
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uint32_t addr = (regs[0x85] << 16) | (regs[0x84] << 8) | m_low[ch];
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uint32_t loop = (regs[0x05] << 16) | (regs[0x04] << 8);
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uint8_t end = regs[6] + 1;
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int8_t v;
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bool fetch=true;
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/* handle looping if we've hit the end */
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if ((addr >> 16) == end)
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{
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if (regs[0x86] & 2)
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{
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regs[0x86] |= 1;
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fetch=false;
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}
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else addr = loop;
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}
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/* fetch the sample */
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if (fetch) {
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v = read_byte(offset + (addr >> 8)) - 0x80;
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/* apply panning and advance */
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if (m_muted[ch]) {
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lastOut[ch][0]=0;
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lastOut[ch][1]=0;
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} else {
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lastOut[ch][0]=v * (regs[2] & 0x7f);
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lastOut[ch][1]=v * (regs[3] & 0x7f);
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}
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outputs[0]+=lastOut[ch][0];
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outputs[1]+=lastOut[ch][1];
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addr = (addr + regs[7]) & 0xffffff;
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} else {
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lastOut[ch][0]=0;
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lastOut[ch][1]=0;
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}
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/* store back the updated address */
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regs[0x84] = addr >> 8;
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regs[0x85] = addr >> 16;
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m_low[ch] = regs[0x86] & 1 ? 0 : addr;
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}
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}
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}
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void segapcm_device::write(unsigned int offset, uint8_t data)
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{
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m_ram[offset & 0x07ff] = data;
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}
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uint8_t segapcm_device::read(unsigned int offset)
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{
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return m_ram[offset & 0x07ff];
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}
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uint8_t* segapcm_device::get_ram() {
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return m_ram;
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}
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unsigned int segapcm_device::get_addr(int ch) {
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uint8_t *regs = &m_ram[8*ch];
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int offset = (regs[0x86] & m_bankmask) << m_bankshift;
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uint32_t addr = (regs[0x85] << 8) | (regs[0x84]) | offset;
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return addr;
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}
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bool segapcm_device::is_playing(int ch) {
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uint8_t *regs = &m_ram[8*ch];
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return !(regs[0x86]&1);
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}
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void segapcm_device::mute(int ch, bool doMute) {
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m_muted[ch&15]=doMute;
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}
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