teensy-audio/output_spdif2.cpp

/* SPDIF for Teensy 3.X
 * Copyright (c) 2015, Frank Bösing, f.boesing@gmx.de,
 * Thanks to KPC & Paul Stoffregen!
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice, development funding notice, and this permission
 * notice shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

 // 2015/08/23: (FB) added mute_PCM() - sets or unsets VALID in VUCP (and adjusts PARITY)

#if defined(__IMXRT1052__) || defined(__IMXRT1062__)
 
#include <Arduino.h>
#include "output_spdif2.h"
#include "utility/imxrt_hw.h"

audio_block_t * AudioOutputSPDIF2::block_left_1st = NULL;
audio_block_t * AudioOutputSPDIF2::block_right_1st = NULL;
audio_block_t * AudioOutputSPDIF2::block_left_2nd = NULL;
audio_block_t * AudioOutputSPDIF2::block_right_2nd = NULL;
uint16_t  AudioOutputSPDIF2::block_left_offset = 0;
uint16_t  AudioOutputSPDIF2::block_right_offset = 0;
bool AudioOutputSPDIF2::update_responsibility = false;
DMAChannel AudioOutputSPDIF2::dma(false);
extern uint16_t spdif_bmclookup[256];

DMAMEM __attribute__((aligned(32)))
static uint32_t SPDIF_tx_buffer[AUDIO_BLOCK_SAMPLES * 4]; //2 KB

#define PREAMBLE_B  (0xE8) //11101000
#define PREAMBLE_M  (0xE2) //11100010
#define PREAMBLE_W  (0xE4) //11100100

#define VUCP_VALID   ((0xCC) << 24)
#define VUCP_INVALID ((0xD4) << 24)// To mute PCM, set VUCP = invalid.

uint32_t  AudioOutputSPDIF2::vucp = VUCP_VALID;

PROGMEM
void AudioOutputSPDIF2::begin(void)
{

	dma.begin(true); // Allocate the DMA channel first

	block_left_1st = NULL;
	block_right_1st = NULL;

	// TODO: should we set & clear the I2S_TCSR_SR bit here?
	config_SPDIF();

	CORE_PIN2_CONFIG  = 2;  //2:TX_DATA0
	const int nbytes_mlno = 2 * 4; // 8 Bytes per minor loop

	dma.TCD->SADDR = SPDIF_tx_buffer;
	dma.TCD->SOFF = 4;
	dma.TCD->ATTR = DMA_TCD_ATTR_SSIZE(2) | DMA_TCD_ATTR_DSIZE(2);
	dma.TCD->NBYTES_MLNO = nbytes_mlno;
	dma.TCD->SLAST = -sizeof(SPDIF_tx_buffer);
	dma.TCD->DADDR = &I2S2_TDR0;
	dma.TCD->DOFF = 0;
	dma.TCD->CITER_ELINKNO = sizeof(SPDIF_tx_buffer) / nbytes_mlno;
	dma.TCD->DLASTSGA = 0;
	dma.TCD->BITER_ELINKNO = sizeof(SPDIF_tx_buffer) / nbytes_mlno;
	dma.TCD->CSR = DMA_TCD_CSR_INTHALF | DMA_TCD_CSR_INTMAJOR;
	dma.triggerAtHardwareEvent(DMAMUX_SOURCE_SAI2_TX);
	update_responsibility = update_setup();
	dma.enable();

	I2S2_TCSR |= I2S_TCSR_TE | I2S_TCSR_BCE | I2S_TCSR_FRDE | I2S_TCSR_FR;
	dma.attachInterrupt(isr);
}

/*

 http://www.hardwarebook.info/S/PDIF

 1. To make it easier and a bit faster, the parity-bit is always the same.
	- With a alternating parity we had to adjust the next subframe. Instead, use a bit from the aux-info as parity.

 2. The buffer is filled with an offset of 1 byte, so the last parity (which is always 0 now (see 1.) ) is written as first byte.
	-> A bit easier and faster to construct both subframes.

*/

void AudioOutputSPDIF2::isr(void)
{
	static uint16_t frame = 0;
	const int16_t *src;
	int32_t *end, *dest;
	audio_block_t *block;
	uint32_t saddr, offset;
	uint16_t sample, lo, hi, aux;

	saddr = (uint32_t)(dma.TCD->SADDR);
	dma.clearInterrupt();
	if (saddr < (uint32_t)SPDIF_tx_buffer + sizeof(SPDIF_tx_buffer) / 2) {
		// DMA is transmitting the first half of the buffer
		// so we must fill the second half
		dest = (int32_t *)&SPDIF_tx_buffer[AUDIO_BLOCK_SAMPLES * 4/2];
		end = (int32_t *)&SPDIF_tx_buffer[AUDIO_BLOCK_SAMPLES * 4];
		if (AudioOutputSPDIF2::update_responsibility) AudioStream::update_all();
	} else {
		// DMA is transmitting the second half of the buffer
		// so we must fill the first half
		dest = (int32_t *)SPDIF_tx_buffer;
		end = (int32_t *)&SPDIF_tx_buffer[AUDIO_BLOCK_SAMPLES * 4/2];
	}

	block = AudioOutputSPDIF2::block_left_1st;
	if (block) {
		offset = AudioOutputSPDIF2::block_left_offset;
		src = &block->data[offset];
		do {

			sample = *src++;

			//Subframe Channel 1
			hi  = spdif_bmclookup[(uint8_t)(sample >> 8)];
			lo  = spdif_bmclookup[(uint8_t) sample];
			lo ^= (~((int16_t)hi) >> 16);
			// 16 Bit sample:
			*(dest+1) = ((uint32_t)lo << 16) | hi;
			// 4 Bit Auxillary-audio-databits, the first used as parity
			aux = (0xB333 ^ (((uint32_t)((int16_t)lo)) >> 17));

			if (++frame > 191) {
				// VUCP-Bits ("Valid, Subcode, Channelstatus, Parity) = 0 (0xcc) | Preamble (depends on Framno.) | Auxillary
				*(dest+0) =  vucp | (PREAMBLE_B << 16 ) | aux; //special preamble for one of 192 frames
				frame = 0;
			} else {
				*(dest+0) = vucp | (PREAMBLE_M << 16 ) | aux;
			}
			dest += 4;

		} while (dest < end);
		offset += AUDIO_BLOCK_SAMPLES/2;
		if (offset < AUDIO_BLOCK_SAMPLES) {
			AudioOutputSPDIF2::block_left_offset = offset;
		} else {
			AudioOutputSPDIF2::block_left_offset = 0;
			AudioStream::release(block);
			AudioOutputSPDIF2::block_left_1st = AudioOutputSPDIF2::block_left_2nd;
			AudioOutputSPDIF2::block_left_2nd = NULL;
		}
	} else {
		do {
			if ( ++frame > 191 ) {
				*(dest+0) = vucp | 0x00e8cccc;
				frame = 0;
			} else {
				*(dest+0) = vucp | 0x00e2cccc;
			}
			*(dest+1) = 0xccccccccUL;

			dest +=4;
		} while (dest < end);
	}


	dest -= AUDIO_BLOCK_SAMPLES * 4/2 - 4/2;
	block = AudioOutputSPDIF2::block_right_1st;
	if (block) {
		offset = AudioOutputSPDIF2::block_right_offset;
		src = &block->data[offset];

		do {
			sample = *src++;

			//Subframe Channel 2
			hi  = spdif_bmclookup[(uint8_t)(sample >> 8)];
			lo  = spdif_bmclookup[(uint8_t)sample];
			lo ^= (~((int16_t)hi) >> 16);

			*(dest+1) = ( ((uint32_t)lo << 16) | hi );

			aux = (0xB333 ^ (((uint32_t)((int16_t)lo)) >> 17));
			*(dest+0)  =  vucp | (PREAMBLE_W << 16 ) | aux;

			dest += 4;
		} while (dest < end);

		offset += AUDIO_BLOCK_SAMPLES/2;
		if (offset < AUDIO_BLOCK_SAMPLES) {
			AudioOutputSPDIF2::block_right_offset = offset;
		} else {
			AudioOutputSPDIF2::block_right_offset = 0;
			AudioStream::release(block);
			AudioOutputSPDIF2::block_right_1st = AudioOutputSPDIF2::block_right_2nd;
			AudioOutputSPDIF2::block_right_2nd = NULL;
		}
	} else {
		do {
			*dest 	= vucp | 0x00e4ccccUL;
			*(dest+1) = 0xccccccccUL;
			dest += 4 ;
		} while (dest < end);
	}

	#if IMXRT_CACHE_ENABLED >= 2
	dest -= AUDIO_BLOCK_SAMPLES * 4/2 + 4/2;
	arm_dcache_flush_delete(dest, sizeof(SPDIF_tx_buffer) / 2 );
	#endif

}

void AudioOutputSPDIF2::mute_PCM(const bool mute)
{
	vucp = mute?VUCP_INVALID:VUCP_VALID;
}

void AudioOutputSPDIF2::update(void)
{

	audio_block_t *block;
	block = receiveReadOnly(0); // input 0 = left channel
	if (block) {

		__disable_irq();
		if (block_left_1st == NULL) {
			block_left_1st = block;
			block_left_offset = 0;
			__enable_irq();
		} else if (block_left_2nd == NULL) {
			block_left_2nd = block;
			__enable_irq();
		} else {
			audio_block_t *tmp = block_left_1st;
			block_left_1st = block_left_2nd;
			block_left_2nd = block;
			block_left_offset = 0;
			__enable_irq();
			release(tmp);
		}
	}
	block = receiveReadOnly(1); // input 1 = right channel
	if (block) {
		__disable_irq();
		if (block_right_1st == NULL) {
			block_right_1st = block;
			block_right_offset = 0;
			__enable_irq();
		} else if (block_right_2nd == NULL) {
			block_right_2nd = block;
			__enable_irq();
		} else {
			audio_block_t *tmp = block_right_1st;
			block_right_1st = block_right_2nd;
			block_right_2nd = block;
			block_right_offset = 0;
			__enable_irq();
			release(tmp);
		}
	}

}

PROGMEM
void AudioOutputSPDIF2::config_SPDIF(void)
{
	CCM_CCGR5 |= CCM_CCGR5_SAI2(CCM_CCGR_ON);
//PLL:
	int fs = AUDIO_SAMPLE_RATE_EXACT;
	// PLL between 27*24 = 648MHz und 54*24=1296MHz
	int n1 = 4; //SAI prescaler 4 => (n1*n2) = multiple of 4
	int n2 = 1 + (24000000 * 27) / (fs * 256 * n1);

	double C = ((double)fs * 256 * n1 * n2) / 24000000;
	int c0 = C;
	int c2 = 10000;
	int c1 = C * c2 - (c0 * c2);
	set_audioClock(c0, c1, c2);

	CCM_CSCMR1 = (CCM_CSCMR1 & ~(CCM_CSCMR1_SAI2_CLK_SEL_MASK))
		   | CCM_CSCMR1_SAI2_CLK_SEL(2); // &0x03 // (0,1,2): PLL3PFD0, PLL5, PLL4,
	CCM_CS2CDR = (CCM_CS2CDR & ~(CCM_CS2CDR_SAI2_CLK_PRED_MASK | CCM_CS2CDR_SAI2_CLK_PODF_MASK))
		   | CCM_CS2CDR_SAI2_CLK_PRED(n1-1)
		   | CCM_CS2CDR_SAI2_CLK_PODF(n2-1);
	IOMUXC_GPR_GPR1 = (IOMUXC_GPR_GPR1 & ~(IOMUXC_GPR_GPR1_SAI2_MCLK3_SEL_MASK))
			| (IOMUXC_GPR_GPR1_SAI2_MCLK_DIR | IOMUXC_GPR_GPR1_SAI2_MCLK3_SEL(0));	//Select MCLK

	// configure transmitter
	I2S2_TMR = 0;
	I2S2_TCR1 = I2S_TCR1_RFW(0);  // watermark
	I2S2_TCR2 = I2S_TCR2_SYNC(0) | I2S_TCR2_MSEL(1) | I2S_TCR2_BCD | I2S_TCR2_DIV(0);
	I2S2_TCR3 = I2S_TCR3_TCE;

	//4 Words per Frame 32 Bit Word-Length -> 128 Bit Frame-Length, MSB First:
	I2S2_TCR4 = I2S_TCR4_FRSZ(3) | I2S_TCR4_SYWD(0) | I2S_TCR4_MF | I2S_TCR4_FSP | I2S_TCR4_FSD;
	I2S2_TCR5 = I2S_TCR5_WNW(31) | I2S_TCR5_W0W(31) | I2S_TCR5_FBT(31);
#if 0
	//debug only:
	CORE_PIN5_CONFIG  = 2;  //2:MCLK	11.43MHz
	CORE_PIN4_CONFIG  = 2;  //2:TX_BCLK	5 MHz
	CORE_PIN3_CONFIG  = 2;  //2:TX_SYNC	44.1 KHz
#endif
}


#else

void AudioOutputSPDIF2::update(void)
{

	audio_block_t *block;
	block = receiveReadOnly(0); // input 0 = left channel
	if (block) release(block);
	block = receiveReadOnly(1); // input 1 = right channel
	if (block) release(block);
}

#endif