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#include <Kernel/Devices/SB16.h>
#include <Kernel/IO.h>
#include <Kernel/Thread.h>
#include <Kernel/VM/MemoryManager.h>
//#define SB16_DEBUG
enum class SampleFormat : u8 {
Signed = 0x10,
Stereo = 0x20,
};
const u16 DSP_READ = 0x22A;
const u16 DSP_WRITE = 0x22C;
const u16 DSP_STATUS = 0x22E;
const u16 DSP_R_ACK = 0x22F;
/* Write a value to the DSP write register */
void SB16::dsp_write(u8 value)
{
while (IO::in8(DSP_WRITE) & 0x80) {
;
}
IO::out8(DSP_WRITE, value);
}
/* Reads the value of the DSP read register */
u8 SB16::dsp_read()
{
while (!(IO::in8(DSP_STATUS) & 0x80)) {
;
}
return IO::in8(DSP_READ);
}
/* Changes the sample rate of sound output */
void SB16::set_sample_rate(uint16_t hz)
{
dsp_write(0x41); // output
dsp_write((u8)(hz >> 8));
dsp_write((u8)hz);
dsp_write(0x42); // input
dsp_write((u8)(hz >> 8));
dsp_write((u8)hz);
}
static SB16* s_the;
SB16::SB16()
: IRQHandler(5)
, CharacterDevice(42, 42) // ### ?
{
s_the = this;
initialize();
}
SB16::~SB16()
{
}
SB16& SB16::the()
{
return *s_the;
}
void SB16::initialize()
{
IO::out8(0x226, 1);
IO::delay();
IO::out8(0x226, 0);
auto data = dsp_read();
if (data != 0xaa) {
kprintf("SB16: sb not ready");
return;
}
// Get the version info
dsp_write(0xe1);
m_major_version = dsp_read();
auto vmin = dsp_read();
kprintf("SB16: found version %d.%d\n", m_major_version, vmin);
enable_irq();
}
bool SB16::can_read(FileDescription&) const
{
return false;
}
ssize_t SB16::read(FileDescription&, u8*, ssize_t)
{
return 0;
}
void SB16::dma_start(uint32_t length)
{
const auto addr = m_dma_buffer_page->paddr().get();
const u8 channel = 5; // 16-bit samples use DMA channel 5 (on the master DMA controller)
const u8 mode = 0;
// Disable the DMA channel
IO::out8(0xd4, 4 + (channel % 4));
// Clear the byte pointer flip-flop
IO::out8(0xd8, 0);
// Write the DMA mode for the transfer
IO::out8(0xd6, (channel % 4) | mode);
// Write the offset of the buffer
u16 offset = (addr / 2) % 65536;
IO::out8(0xc4, (u8)offset);
IO::out8(0xc4, (u8)(offset >> 8));
// Write the transfer length
IO::out8(0xc6, (u8)(length - 1));
IO::out8(0xc6, (u8)((length - 1) >> 8));
// Write the buffer
IO::out8(0x8b, addr >> 16);
// Enable the DMA channel
IO::out8(0xd4, (channel % 4));
}
void SB16::handle_irq()
{
// Stop sound output ready for the next block.
dsp_write(0xd5);
IO::in8(DSP_STATUS); // 8 bit interrupt
if (m_major_version >= 4)
IO::in8(DSP_R_ACK); // 16 bit interrupt
m_interrupted = true;
}
void SB16::wait_for_irq()
{
// Well, we have no way of knowing how much got written. So just hope all of
// it did, even if we're interrupted.
(void)current->block_until("Interrupting", [this] {
return m_interrupted;
});
}
ssize_t SB16::write(FileDescription&, const u8* data, ssize_t length)
{
if (!m_dma_buffer_page)
m_dma_buffer_page = MM.allocate_supervisor_physical_page();
#ifdef SB16_DEBUG
kprintf("SB16: Writing buffer of %d bytes\n", length);
#endif
ASSERT(length <= PAGE_SIZE);
const int BLOCK_SIZE = 32 * 1024;
if (length > BLOCK_SIZE) {
return -ENOSPC;
}
u8 mode = (u8)SampleFormat::Signed | (u8)SampleFormat::Stereo;
disable_irq();
const int sample_rate = 44100;
set_sample_rate(sample_rate);
memcpy(m_dma_buffer_page->paddr().as_ptr(), data, length);
dma_start(length);
// 16-bit single-cycle output.
// FIXME: Implement auto-initialized output.
u8 command = 0xb0;
u16 sample_count = length / sizeof(i16);
if (mode & (u8)SampleFormat::Stereo)
sample_count /= 2;
sample_count -= 1;
dsp_write(command);
dsp_write(mode);
dsp_write((u8)sample_count);
dsp_write((u8)(sample_count >> 8));
m_interrupted = false;
enable_irq();
wait_for_irq();
return length;
}
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