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Fix class 1 noise by using channel buffering

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This commit is contained in:
Ed Clarke
2018-10-29 13:29:19 +00:00
parent 12327505e5
commit 40ea575589
2 changed files with 16 additions and 10 deletions
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4
examples/xua_lite_example/src/audio_hub.xc
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@@ -41,8 +41,8 @@ void AudioHub(server i2s_frame_callback_if i2s,
case i2s.restart_check() -> i2s_restart_t restart:
restart = I2S_NO_RESTART; // Keep on looping
for (int i = 0; i < NUM_USB_CHAN_IN; i++) c_audio_hub <: samples_in[i];
for (int i = 0; i < NUM_USB_CHAN_OUT; i++) c_audio_hub :> samples_out[i];
for (int i = 0; i < NUM_USB_CHAN_OUT; i++) samples_out[i] = (int)inuint(c_audio_hub);
for (int i = 0; i < NUM_USB_CHAN_IN; i++) outuint(c_audio_hub, (unsigned)samples_in[i]);
//delay_microseconds(5); //Test backpressure tolerance
break;
}

22
examples/xua_lite_example/src/xua_buffer.xc
View File

@@ -214,6 +214,10 @@ void XUA_Buffer_lite(chanend c_ep0_out, chanend c_ep0_in, chanend c_aud_out, cha
XUD_SetReady_InPtr(ep_feedback, (unsigned)fb_clocks, (AUDIO_CLASS == 2) ? 4 : 3);
XUD_SetReady_Out(ep0_out, sbuffer);
//Send initial samples so audiohub is not blocked
for (int i = 0; i < NUM_USB_CHAN_OUT; i++) outuint(c_audio_hub, 0);
//Unsafe to allow us to use fifo API
unsafe{
@@ -224,8 +228,7 @@ void XUA_Buffer_lite(chanend c_ep0_out, chanend c_ep0_in, chanend c_aud_out, cha
//XUD transaction variables passed in by reference
XUD_Result_t result;
unsigned length = 0;
unsigned tmp; //For select channel input by ref
unsigned u_tmp; //For select channel input by ref
while(1){
select{
//Handle EP0 requests
@@ -238,7 +241,7 @@ void XUA_Buffer_lite(chanend c_ep0_out, chanend c_ep0_in, chanend c_aud_out, cha
break;
//SOF handling
case inuint_byref(c_sof, tmp):
case inuint_byref(c_sof, u_tmp):
unsigned mclk_port_counter = 0;
asm volatile(" getts %0, res[%1]" : "=r" (mclk_port_counter) : "r" (p_for_mclk_count));
do_feedback_calculation(sof_count, mclk_hz, mclk_port_counter, mclk_port_counter_old, feedback_value, mod_from_last_time, fb_clocks);
@@ -277,14 +280,17 @@ void XUA_Buffer_lite(chanend c_ep0_out, chanend c_ep0_in, chanend c_aud_out, cha
num_samples_to_send_to_host = 0;
break;
//Exchange samples with audiohub
case c_audio_hub :> samples_in[0]:
for (int i = 1; i < NUM_USB_CHAN_IN; i++) c_audio_hub :> samples_in[i];
// for (int i = 0; i < NUM_USB_CHAN_OUT; i++) c_audio_hub <: samples_out[1];
//Exchange samples with audiohub. Note we are using channel buffering here to act as a FIFO
case inuint_byref(c_audio_hub, u_tmp):
samples_in[0] = (int)u_tmp;
for (int i = 1; i < NUM_USB_CHAN_IN; i++){
u_tmp = inuint(c_audio_hub);
samples_in[i] = (int)u_tmp;
}
int out_samps[NUM_USB_CHAN_OUT];
fifo_ret_t ret = fifo_block_pop(host_to_device_fifo_ptr, out_samps, NUM_USB_CHAN_OUT);
//if (ret != FIFO_SUCCESS) debug_printf("empty\n");
for (int i = 0; i < NUM_USB_CHAN_OUT; i++) c_audio_hub <: out_samps[i];
for (int i = 0; i < NUM_USB_CHAN_OUT; i++) outuint(c_audio_hub, (unsigned) out_samps[i]);
break;
}
}