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Transfer dma data in small, timed, chunks (sb16)

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This allows double buffering method of audio transfer, as the memory
would get updated progressively.

See http://the.earth.li/~tfm/oldpage/sb_wave.html
This commit is contained in:
Ernest Wong 2017-11-19 11:50:38 +13:00 committed by Fabian
parent ff646aac6c
commit b868e48283
2 changed files with 64 additions and 35 deletions
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5
src/dma.js
View file

@ -308,6 +308,11 @@ DMA.prototype.do_write = function(buffer, start, len, channel, fn)
if(len < read_count)
{
dbg_log("DMA should read more than provided", LOG_DMA);
read_count = len;
}
else if(len > read_count)
{
dbg_log("DMA attempted to read more than provided", LOG_DMA);
}
if(start + read_count > buffer.byteLength)

94
src/sb16.js
View file

@ -6,6 +6,7 @@ var
/** @const */ DSP_BUFSIZE = 64,
/** @const */ DSP_DACSIZE = 65536,
/** @const */ DMA_BUFSIZE = 65536,
/** @const */ DMA_BLOCK_SAMPLES = 1024,
/** @const */ DMA_CHANNEL_8BIT = 1, // (ISA DMA standard sound card channels)
/** @const */ DMA_CHANNEL_16BIT = 5,
/** @const */ SB_IRQ = 5,
@ -32,6 +33,9 @@ function SB16(cpu, bus)
/** @const @type {CPU} */
this.cpu = cpu;
/** @const @type {BusConnector} */
this.bus = bus;
// I/O Buffers.
this.write_buffer = new ByteQueue(DSP_BUFSIZE);
this.read_buffer = new ByteQueue(DSP_BUFSIZE);
@ -66,7 +70,10 @@ function SB16(cpu, bus)
// Direct Memory Access transfer info.
this.dma = cpu.devices.dma;
this.dma_transfer_size = 0; // in samples
this.dma_sample_count = 0;
this.dma_bytes_count = 0;
this.dma_bytes_left = 0;
this.dma_bytes_block = 0;
this.dma_irq = 0;
this.dma_channel = 0;
this.dma_channel_8bit = DMA_CHANNEL_8BIT;
@ -79,6 +86,7 @@ function SB16(cpu, bus)
this.dma_buffer_uint16 = new Uint16Array(this.dma_buffer);
this.dma_syncbuffer = new SyncBuffer(this.dma_buffer);
this.sampling_rate = 22050;
this.bytes_per_sample = 1;
// DMA identification data
this.e2_value = 0xAA;
@ -170,7 +178,10 @@ SB16.prototype.reset_dsp = function()
this.dac_buffer.clear();
this.dma_transfer_size = 0;
this.dma_sample_count = 0;
this.dma_bytes_count = 0;
this.dma_bytes_left = 0;
this.dma_bytes_block = 0;
this.dma_irq = 0;
this.dma_channel = 0;
this.dma_autoinit = false;
@ -180,6 +191,7 @@ SB16.prototype.reset_dsp = function()
this.e2_count = 0;
this.sampling_rate = 22050;
this.bytes_per_sample = 1;
this.lower_irq(SB_IRQ_8BIT);
this.irq_triggered.fill(0);
@ -818,17 +830,15 @@ register_dsp_command([0xE2], 1, function()
this.e2_count++;
this.e2_value %= 256;
var sb16 = this;
this.dma.on_unmask(this.dma_channel_8bit, function()
this.dma.on_unmask(this.dma_channel_8bit, () =>
{
sb16.dma.on_unmask(sb16.dma_channel_8bit, undefined);
this.dma.on_unmask(this.dma_channel_8bit, undefined);
var buffer = new Uint8Array(1);
buffer[0] = sb16.e2_value;
buffer[0] = this.e2_value;
var syncbuffer = new SyncBuffer(buffer);
sb16.dma.do_read(syncbuffer, 0, 1, sb16.dma_channel_8bit, function()
this.dma.do_read(syncbuffer, 0, 1, this.dma_channel_8bit, function()
{
dbg_log("e2 dma identification: written to dma", LOG_SB16);
});
@ -1010,6 +1020,7 @@ register_mixer_read(0x82, function()
SB16.prototype.sampling_rate_change = function(rate)
{
this.bus.send("speaker-samplerate", rate);
this.sampling_rate = rate;
}
@ -1020,7 +1031,7 @@ SB16.prototype.get_channel_count = function()
SB16.prototype.dma_transfer_size_set = function()
{
this.dma_transfer_size = 1
this.dma_sample_count = 1
+ (this.write_buffer.shift() << 0)
+ (this.write_buffer.shift() << 8);
}
@ -1028,28 +1039,50 @@ SB16.prototype.dma_transfer_size_set = function()
SB16.prototype.dma_transfer_start = function()
{
dbg_log("begin dma transfer", LOG_SB16);
var irq = this.dma_irq;
var sb16 = this;
this.bytes_per_sample = 1;
if(this.dsp_16bit) this.bytes_per_sample *= 2;
if(this.dsp_stereo) this.bytes_per_sample *= 2;
var size = this.dma_transfer_size;
if(this.dsp_16bit) size *= 2;
if(this.dsp_stereo) size *= 2;
this.dma_bytes_count = this.dma_sample_count * this.bytes_per_sample;
this.dma_bytes_block = DMA_BLOCK_SAMPLES * this.bytes_per_sample;
this.dma.on_unmask(this.dma_channel, function()
this.dma.on_unmask(this.dma_channel, () =>
{
sb16.dma.on_unmask(sb16.dma_channel, undefined);
sb16.dma.do_write(sb16.dma_syncbuffer, 0, size, sb16.dma_channel, function(error)
{
dbg_log("dma transfer " + (error ? "unsuccessful" : "successful"), LOG_SB16);
sb16.dma_to_dac();
sb16.raise_irq(irq);
});
this.dma.on_unmask(this.dma_channel, undefined);
this.dma_bytes_left = this.dma_bytes_count;
});
}
SB16.prototype.dma_to_dac = function()
SB16.prototype.dma_transfer_next = function()
{
if(!this.dma_bytes_left) return;
dbg_log("dma transfering next block", LOG_SB16);
var size = Math.min(this.dma_bytes_left, this.dma_bytes_block);
var samples = Math.floor(size / this.bytes_per_sample);
this.dma.do_write(this.dma_syncbuffer, 0, size, this.dma_channel, (error) =>
{
dbg_log("dma block transfer " + (error ? "unsuccessful" : "successful"), LOG_SB16);
if(error) return;
this.dma_to_dac(samples);
this.dma_bytes_left -= size;
if(!this.dma_bytes_left)
{
this.raise_irq(this.dma_irq);
if(this.dma_autoinit)
{
this.dma_bytes_left = this.dma_bytes_count;
}
}
});
}
SB16.prototype.dma_to_dac = function(sample_count)
{
var amplitude = this.dsp_16bit? 32767.5 : 127.5;
var offset = this.dsp_signed? 0 : -1;
@ -1069,7 +1102,7 @@ SB16.prototype.dma_to_dac = function()
this.dma_buffer_uint8;
}
for(var i = 0; i < this.dma_transfer_size; i++)
for(var i = 0; i < sample_count; i++)
{
for(var j = 0; j < repeats; j++)
{
@ -1090,16 +1123,7 @@ SB16.prototype.audio_process = function(event)
out1[i] = (!!this.dac_buffer.length) * this.dac_buffer.shift();
}
if(this.dma_autoinit)
{
// Resend. Emulate DMA autoinit mode.
this.dma_to_dac();
}
else
{
// Clear.
this.dma_buffer_uint8.fill(0);
}
setTimeout(() => { this.dma_transfer_next(); }, 0);
}
SB16.prototype.raise_irq = function(type)