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)

#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;

/* DMAMEM */ static uint32_t SPDIF_tx_buffer[AUDIO_BLOCK_SAMPLES * 4]; //2 KB
DMAChannel AudioOutputSPDIF2::dma(false);

#if defined(__IMXRT1052__) || defined(__IMXRT1062__)

#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;

static const
uint16_t bmclookup[256] = { //biphase mark encoded values (least significant bit first)
	0xcccc, 0x4ccc, 0x2ccc, 0xaccc, 0x34cc, 0xb4cc, 0xd4cc, 0x54cc,
	0x32cc, 0xb2cc, 0xd2cc, 0x52cc, 0xcacc, 0x4acc, 0x2acc, 0xaacc,
	0x334c, 0xb34c, 0xd34c, 0x534c, 0xcb4c, 0x4b4c, 0x2b4c, 0xab4c,
	0xcd4c, 0x4d4c, 0x2d4c, 0xad4c, 0x354c, 0xb54c, 0xd54c, 0x554c,
	0x332c, 0xb32c, 0xd32c, 0x532c, 0xcb2c, 0x4b2c, 0x2b2c, 0xab2c,
	0xcd2c, 0x4d2c, 0x2d2c, 0xad2c, 0x352c, 0xb52c, 0xd52c, 0x552c,
	0xccac, 0x4cac, 0x2cac, 0xacac, 0x34ac, 0xb4ac, 0xd4ac, 0x54ac,
	0x32ac, 0xb2ac, 0xd2ac, 0x52ac, 0xcaac, 0x4aac, 0x2aac, 0xaaac,
	0x3334, 0xb334, 0xd334, 0x5334, 0xcb34, 0x4b34, 0x2b34, 0xab34,
	0xcd34, 0x4d34, 0x2d34, 0xad34, 0x3534, 0xb534, 0xd534, 0x5534,
	0xccb4, 0x4cb4, 0x2cb4, 0xacb4, 0x34b4, 0xb4b4, 0xd4b4, 0x54b4,
	0x32b4, 0xb2b4, 0xd2b4, 0x52b4, 0xcab4, 0x4ab4, 0x2ab4, 0xaab4,
	0xccd4, 0x4cd4, 0x2cd4, 0xacd4, 0x34d4, 0xb4d4, 0xd4d4, 0x54d4,
	0x32d4, 0xb2d4, 0xd2d4, 0x52d4, 0xcad4, 0x4ad4, 0x2ad4, 0xaad4,
	0x3354, 0xb354, 0xd354, 0x5354, 0xcb54, 0x4b54, 0x2b54, 0xab54,
	0xcd54, 0x4d54, 0x2d54, 0xad54, 0x3554, 0xb554, 0xd554, 0x5554,
	0x3332, 0xb332, 0xd332, 0x5332, 0xcb32, 0x4b32, 0x2b32, 0xab32,
	0xcd32, 0x4d32, 0x2d32, 0xad32, 0x3532, 0xb532, 0xd532, 0x5532,
	0xccb2, 0x4cb2, 0x2cb2, 0xacb2, 0x34b2, 0xb4b2, 0xd4b2, 0x54b2,
	0x32b2, 0xb2b2, 0xd2b2, 0x52b2, 0xcab2, 0x4ab2, 0x2ab2, 0xaab2,
	0xccd2, 0x4cd2, 0x2cd2, 0xacd2, 0x34d2, 0xb4d2, 0xd4d2, 0x54d2,
	0x32d2, 0xb2d2, 0xd2d2, 0x52d2, 0xcad2, 0x4ad2, 0x2ad2, 0xaad2,
	0x3352, 0xb352, 0xd352, 0x5352, 0xcb52, 0x4b52, 0x2b52, 0xab52,
	0xcd52, 0x4d52, 0x2d52, 0xad52, 0x3552, 0xb552, 0xd552, 0x5552,
	0xccca, 0x4cca, 0x2cca, 0xacca, 0x34ca, 0xb4ca, 0xd4ca, 0x54ca,
	0x32ca, 0xb2ca, 0xd2ca, 0x52ca, 0xcaca, 0x4aca, 0x2aca, 0xaaca,
	0x334a, 0xb34a, 0xd34a, 0x534a, 0xcb4a, 0x4b4a, 0x2b4a, 0xab4a,
	0xcd4a, 0x4d4a, 0x2d4a, 0xad4a, 0x354a, 0xb54a, 0xd54a, 0x554a,
	0x332a, 0xb32a, 0xd32a, 0x532a, 0xcb2a, 0x4b2a, 0x2b2a, 0xab2a,
	0xcd2a, 0x4d2a, 0x2d2a, 0xad2a, 0x352a, 0xb52a, 0xd52a, 0x552a,
	0xccaa, 0x4caa, 0x2caa, 0xacaa, 0x34aa, 0xb4aa, 0xd4aa, 0x54aa,
	0x32aa, 0xb2aa, 0xd2aa, 0x52aa, 0xcaaa, 0x4aaa, 0x2aaa, 0xaaaa
};

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  = bmclookup[(uint8_t)(sample >> 8)];
			lo  = 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  = bmclookup[(uint8_t)(sample >> 8)];
			lo  = 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);
	}

}

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);
		}
	}

}

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