/***************************************************************************//**
 *   @file   dac.cpp
 *   @brief  Implementation of dac.cpp
 *   @author
 *******************************************************************************
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 *
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 *    distribution.
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 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *  - The use of this software may or may not infringe the patent rights
 *    of one or more patent holders.  This license does not release you
 *    from the requirement that you obtain separate licenses from these
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 *
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#include <ADuCM360.h>
#include <cmath>
#include <errno.h>
#include <cstring>
#include <hal/devices.h>
#include <hal/drivers/flash.h>
#include <hal/drivers/dac.h>

//schematic: (0x0fff0000 * 15k) / (1.2v * (15k + 110k)) = 26836992
#define GAIN 26836992.f

static int position = 0;

ssize_t dac_read(void *buf, size_t count)
{
	dac_file file;

	file.voltage = pADI_DAC->DACDAT / GAIN;

	if ((position + count) > sizeof(dac_file)) {
		count = sizeof(dac_file) - position;
	}

	memcpy(buf, (char*) (&file) + position, count);

	position += count;

	return count;
}

ssize_t dac_write(const void *buf, size_t count)
{
	dac_file file;

	file.voltage = pADI_DAC->DACDAT / GAIN;

	if ((position + count) > sizeof(dac_file)) {
		count = sizeof(dac_file) - position;
	}

	memcpy((char*) (&file) + position, buf, count);

	position += count;

	if (file.voltage <= configure_file.max_voltage
	    && file.voltage >= configure_file.min_voltage) {
		pADI_DAC->DACDAT = lround(file.voltage * GAIN);
	}

	return count;
}

off_t dac_lseek(off_t offset, int whence)
{
	switch (whence) {
	case SEEK_SET:
		if (offset > sizeof(dac_file) || offset < 0) {
			errno = EINVAL;
			return -1;
		} else {
			position = offset;
		}
		break;
	case SEEK_CUR:
		if ((position + offset) > sizeof(dac_file) || (position + offset) < 0) {
			errno = EINVAL;
			return -1;
		} else {
			position += offset;
		}
		break;
	case SEEK_END:
		if (offset > 0 || (sizeof(dac_file) + offset) < 0) {
			errno = EINVAL;
			return -1;
		} else {
			position = sizeof(dac_file) + offset;
		}
		break;
	default:
		errno = ENXIO;
		return -1;
		break;
	}

	return position;
}

void dac_open(void)
{
	CLKDIS_DISDACCLK_BBA = false;

	pADI_ANA->REFCTRL = REFCTRL_REFPD_DIS;

	pADI_DAC->DACCON = DACCON_DMAEN_Off | DACCON_PD_DIS | DACCON_NPN_DIS |
			   DACCON_BUFBYP_DIS | DACCON_CLK_HCLK
			   | DACCON_CLR_On | DACCON_MDE_16BitFast |
			   DACCON_RNG_IntVref; //please check with user guide, DACCON_MDE_16BitFast is slow mode

	DACCON_CLR_BBA = true;

	flash_file * p_flash_file;

	decltype(flash_file::voltage) voltage;

	fseek(p_flash, (int) (&p_flash_file->voltage) - (int) (p_flash_file), SEEK_SET);
	fread(&voltage, sizeof(dac_file::voltage), 1, p_flash);

	pADI_DAC->DACDAT = lround(voltage * GAIN);
}