[libsigrok.git] / src / dmm / rs9lcd.c

/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * RadioShack 22-812 protocol parser.
 *
 * This protocol is currently encountered on the RadioShack 22-812 DMM.
 * It is a 9-byte packet representing a 1:1 mapping of the LCD segments, hence
 * the name rs9lcd.
 *
 * The chip is a bare die covered by a plastic blob. It is unclear if this chip
 * and protocol is used on any other device.
 */

#include <string.h>
#include <ctype.h>
#include <math.h>
#include <glib.h>
#include <libsigrok/libsigrok.h>
#include "libsigrok-internal.h"

#define LOG_PREFIX "rs9lcd"

/* Byte 1 of the packet, and the modes it represents */
#define IND1_HZ		(1 << 7)
#define IND1_OHM	(1 << 6)
#define IND1_KILO	(1 << 5)
#define IND1_MEGA	(1 << 4)
#define IND1_FARAD	(1 << 3)
#define IND1_AMP	(1 << 2)
#define IND1_VOLT	(1 << 1)
#define IND1_MILI	(1 << 0)
/* Byte 2 of the packet, and the modes it represents */
#define IND2_MICRO	(1 << 7)
#define IND2_NANO	(1 << 6)
#define IND2_DBM	(1 << 5)
#define IND2_SEC	(1 << 4)
#define IND2_DUTY	(1 << 3)
#define IND2_HFE	(1 << 2)
#define IND2_REL	(1 << 1)
#define IND2_MIN	(1 << 0)
/* Byte 7 of the packet, and the modes it represents */
#define INFO_BEEP	(1 << 7)
#define INFO_DIODE	(1 << 6)
#define INFO_BAT	(1 << 5)
#define INFO_HOLD	(1 << 4)
#define INFO_NEG	(1 << 3)
#define INFO_AC		(1 << 2)
#define INFO_RS232	(1 << 1)
#define INFO_AUTO	(1 << 0)
/* Instead of a decimal point, digit 4 carries the MAX flag */
#define DIG4_MAX	(1 << 3)
/* Mask to remove the decimal point from a digit */
#define DP_MASK		(1 << 3)

/* What the LCD values represent */
#define LCD_0		0xd7
#define LCD_1		0x50
#define LCD_2		0xb5
#define LCD_3		0xf1
#define LCD_4		0x72
#define LCD_5		0xe3
#define LCD_6		0xe7
#define LCD_7		0x51
#define LCD_8		0xf7
#define LCD_9		0xf3

#define LCD_C		0x87
#define LCD_E
#define LCD_F
#define LCD_h		0x66
#define LCD_H		0x76
#define LCD_I
#define LCD_n
#define LCD_P		0x37
#define LCD_r

enum {
	MODE_DC_V	= 0,
	MODE_AC_V	= 1,
	MODE_DC_UA	= 2,
	MODE_DC_MA	= 3,
	MODE_DC_A 	= 4,
	MODE_AC_UA	= 5,
	MODE_AC_MA	= 6,
	MODE_AC_A	= 7,
	MODE_OHM	= 8,
	MODE_FARAD	= 9,
	MODE_HZ		= 10,
	MODE_VOLT_HZ	= 11,	/* Dial set to V, Hz selected by Hz button */
	MODE_AMP_HZ	= 12,	/* Dial set to A, Hz selected by Hz button */
	MODE_DUTY	= 13,
	MODE_VOLT_DUTY	= 14,	/* Dial set to V, duty cycle selected */
	MODE_AMP_DUTY	= 15,	/* Dial set to A, duty cycle selected */
	MODE_WIDTH	= 16,
	MODE_VOLT_WIDTH	= 17,	/* Dial set to V, pulse width selected */
	MODE_AMP_WIDTH	= 18,	/* Dial set to A, pulse width selected */
	MODE_DIODE	= 19,
	MODE_CONT	= 20,
	MODE_HFE	= 21,
	MODE_LOGIC	= 22,
	MODE_DBM	= 23,
	/* MODE_EF	= 24, */ /* Not encountered on any DMM */
	MODE_TEMP	= 25,
	MODE_INVALID	= 26,
};

enum {
	READ_ALL,
	READ_TEMP,
};

struct rs9lcd_packet {
	uint8_t mode;
	uint8_t indicatrix1;
	uint8_t indicatrix2;
	uint8_t digit4;
	uint8_t digit3;
	uint8_t digit2;
	uint8_t digit1;
	uint8_t info;
	uint8_t checksum;
};

static gboolean checksum_valid(const struct rs9lcd_packet *rs_packet)
{
	uint8_t *raw;
	uint8_t sum = 0;
	int i;

	raw = (void *)rs_packet;

	for (i = 0; i < RS9LCD_PACKET_SIZE - 1; i++)
		sum += raw[i];

	/* This is just a funky constant added to the checksum. */
	sum += 57;
	sum -= rs_packet->checksum;
	return (sum == 0);
}

static gboolean selection_good(const struct rs9lcd_packet *rs_packet)
{
	int count;

	/* Does the packet have more than one multiplier? */
	count = 0;
	count += (rs_packet->indicatrix1 & IND1_KILO)  ? 1 : 0;
	count += (rs_packet->indicatrix1 & IND1_MEGA)  ? 1 : 0;
	count += (rs_packet->indicatrix1 & IND1_MILI)  ? 1 : 0;
	count += (rs_packet->indicatrix2 & IND2_MICRO) ? 1 : 0;
	count += (rs_packet->indicatrix2 & IND2_NANO)  ? 1 : 0;
	if (count > 1) {
		sr_dbg("More than one multiplier detected in packet.");
		return FALSE;
	}

	/* Does the packet "measure" more than one type of value? */
	count = 0;
	count += (rs_packet->indicatrix1 & IND1_HZ)    ? 1 : 0;
	count += (rs_packet->indicatrix1 & IND1_OHM)   ? 1 : 0;
	count += (rs_packet->indicatrix1 & IND1_FARAD) ? 1 : 0;
	count += (rs_packet->indicatrix1 & IND1_AMP)   ? 1 : 0;
	count += (rs_packet->indicatrix1 & IND1_VOLT)  ? 1 : 0;
	count += (rs_packet->indicatrix2 & IND2_DBM)   ? 1 : 0;
	count += (rs_packet->indicatrix2 & IND2_SEC)   ? 1 : 0;
	count += (rs_packet->indicatrix2 & IND2_DUTY)  ? 1 : 0;
	count += (rs_packet->indicatrix2 & IND2_HFE)   ? 1 : 0;
	if (count > 1) {
		sr_dbg("More than one measurement type detected in packet.");
		return FALSE;
	}

	return TRUE;
}

/*
 * Since the 22-812 does not identify itself in any way, shape, or form,
 * we really don't know for sure who is sending the data. We must use every
 * possible check to filter out bad packets, especially since detection of the
 * 22-812 depends on how well we can filter the packets.
 */
SR_PRIV gboolean sr_rs9lcd_packet_valid(const uint8_t *buf)
{
	const struct rs9lcd_packet *rs_packet = (void *)buf;

	/*
	 * Check for valid mode first, before calculating the checksum. No
	 * point calculating the checksum, if we know we'll reject the packet.
	 */
	if (!(rs_packet->mode < MODE_INVALID))
		return FALSE;

	if (!checksum_valid(rs_packet)) {
		sr_spew("Packet with invalid checksum. Discarding.");
		return FALSE;
	}

	if (!selection_good(rs_packet)) {
		sr_spew("Packet with invalid selection bits. Discarding.");
		return FALSE;
	}

	return TRUE;
}

static uint8_t decode_digit(uint8_t raw_digit)
{
	/* Take out the decimal point, so we can use a simple switch(). */
	raw_digit &= ~DP_MASK;

	switch (raw_digit) {
	case 0x00:
	case LCD_0:
		return 0;
	case LCD_1:
		return 1;
	case LCD_2:
		return 2;
	case LCD_3:
		return 3;
	case LCD_4:
		return 4;
	case LCD_5:
		return 5;
	case LCD_6:
		return 6;
	case LCD_7:
		return 7;
	case LCD_8:
		return 8;
	case LCD_9:
		return 9;
	default:
		sr_dbg("Invalid digit byte: 0x%02x.", raw_digit);
		return 0xff;
	}
}

static double lcd_to_double(const struct rs9lcd_packet *rs_packet, int type)
{
	double rawval = 0, multiplier = 1;
	uint8_t digit, raw_digit;
	gboolean dp_reached = FALSE;
	int i, end;

	/* end = 1: Don't parse last digit. end = 0: Parse all digits. */
	end = (type == READ_TEMP) ? 1 : 0;

	/* We have 4 digits, and we start from the most significant. */
	for (i = 3; i >= end; i--) {
		raw_digit = *(&(rs_packet->digit4) + i);
		digit = decode_digit(raw_digit);
		if (digit == 0xff) {
			rawval = NAN;
			break;
		}
		/*
		 * Digit 1 does not have a decimal point. Instead, the decimal
		 * point is used to indicate MAX, so we must avoid testing it.
		 */
		if ((i < 3) && (raw_digit & DP_MASK))
			dp_reached = TRUE;
		if (dp_reached)
			multiplier /= 10;
		rawval = rawval * 10 + digit;
	}
	rawval *= multiplier;
	if (rs_packet->info & INFO_NEG)
		rawval *= -1;

	/* See if we need to multiply our raw value by anything. */
	if (rs_packet->indicatrix1 & IND2_NANO)
		rawval *= 1E-9;
	else if (rs_packet->indicatrix2 & IND2_MICRO)
		rawval *= 1E-6;
	else if (rs_packet->indicatrix1 & IND1_MILI)
		rawval *= 1E-3;
	else if (rs_packet->indicatrix1 & IND1_KILO)
		rawval *= 1E3;
	else if (rs_packet->indicatrix1 & IND1_MEGA)
		rawval *= 1E6;

	return rawval;
}

static gboolean is_celsius(const struct rs9lcd_packet *rs_packet)
{
	return ((rs_packet->digit4 & ~DP_MASK) == LCD_C);
}

static gboolean is_shortcirc(const struct rs9lcd_packet *rs_packet)
{
	return ((rs_packet->digit2 & ~DP_MASK) == LCD_h);
}

static gboolean is_logic_high(const struct rs9lcd_packet *rs_packet)
{
	sr_spew("Digit 2: 0x%02x.", rs_packet->digit2 & ~DP_MASK);
	return ((rs_packet->digit2 & ~DP_MASK) == LCD_H);
}

SR_PRIV int sr_rs9lcd_parse(const uint8_t *buf, float *floatval,
			    struct sr_datafeed_analog *analog, void *info)
{
	const struct rs9lcd_packet *rs_packet = (void *)buf;
	double rawval;

	(void)info;

	rawval = lcd_to_double(rs_packet, READ_ALL);

	switch (rs_packet->mode) {
	case MODE_DC_V:
		analog->mq = SR_MQ_VOLTAGE;
		analog->unit = SR_UNIT_VOLT;
		analog->mqflags |= SR_MQFLAG_DC;
		break;
	case MODE_AC_V:
		analog->mq = SR_MQ_VOLTAGE;
		analog->unit = SR_UNIT_VOLT;
		analog->mqflags |= SR_MQFLAG_AC;
		break;
	case MODE_DC_UA:	/* Fall through */
	case MODE_DC_MA:	/* Fall through */
	case MODE_DC_A:
		analog->mq = SR_MQ_CURRENT;
		analog->unit = SR_UNIT_AMPERE;
		analog->mqflags |= SR_MQFLAG_DC;
		break;
	case MODE_AC_UA:	/* Fall through */
	case MODE_AC_MA:	/* Fall through */
	case MODE_AC_A:
		analog->mq = SR_MQ_CURRENT;
		analog->unit = SR_UNIT_AMPERE;
		analog->mqflags |= SR_MQFLAG_AC;
		break;
	case MODE_OHM:
		analog->mq = SR_MQ_RESISTANCE;
		analog->unit = SR_UNIT_OHM;
		break;
	case MODE_FARAD:
		analog->mq = SR_MQ_CAPACITANCE;
		analog->unit = SR_UNIT_FARAD;
		break;
	case MODE_CONT:
		analog->mq = SR_MQ_CONTINUITY;
		analog->unit = SR_UNIT_BOOLEAN;
		rawval = is_shortcirc(rs_packet);
		break;
	case MODE_DIODE:
		analog->mq = SR_MQ_VOLTAGE;
		analog->unit = SR_UNIT_VOLT;
		analog->mqflags |= SR_MQFLAG_DIODE | SR_MQFLAG_DC;
		break;
	case MODE_HZ:		/* Fall through */
	case MODE_VOLT_HZ:	/* Fall through */
	case MODE_AMP_HZ:
		analog->mq = SR_MQ_FREQUENCY;
		analog->unit = SR_UNIT_HERTZ;
		break;
	case MODE_LOGIC:
		/*
		 * No matter whether or not we have an actual voltage reading,
		 * we are measuring voltage, so we set our MQ as VOLTAGE.
		 */
		analog->mq = SR_MQ_VOLTAGE;
		if (!isnan(rawval)) {
			/* We have an actual voltage. */
			analog->unit = SR_UNIT_VOLT;
		} else {
			/* We have either HI or LOW. */
			analog->unit = SR_UNIT_BOOLEAN;
			rawval = is_logic_high(rs_packet);
		}
		break;
	case MODE_HFE:
		analog->mq = SR_MQ_GAIN;
		analog->unit = SR_UNIT_UNITLESS;
		break;
	case MODE_DUTY:		/* Fall through */
	case MODE_VOLT_DUTY:	/* Fall through */
	case MODE_AMP_DUTY:
		analog->mq = SR_MQ_DUTY_CYCLE;
		analog->unit = SR_UNIT_PERCENTAGE;
		break;
	case MODE_WIDTH:	/* Fall through */
	case MODE_VOLT_WIDTH:	/* Fall through */
	case MODE_AMP_WIDTH:
		analog->mq = SR_MQ_PULSE_WIDTH;
		analog->unit = SR_UNIT_SECOND;
		break;
	case MODE_TEMP:
		analog->mq = SR_MQ_TEMPERATURE;
		/* We need to reparse. */
		rawval = lcd_to_double(rs_packet, READ_TEMP);
		analog->unit = is_celsius(rs_packet) ?
				SR_UNIT_CELSIUS : SR_UNIT_FAHRENHEIT;
		break;
	case MODE_DBM:
		analog->mq = SR_MQ_POWER;
		analog->unit = SR_UNIT_DECIBEL_MW;
		analog->mqflags |= SR_MQFLAG_AC;
		break;
	default:
		sr_dbg("Unknown mode: %d.", rs_packet->mode);
		break;
	}

	if (rs_packet->info & INFO_HOLD)
		analog->mqflags |= SR_MQFLAG_HOLD;
	if (rs_packet->digit4 & DIG4_MAX)
		analog->mqflags |= SR_MQFLAG_MAX;
	if (rs_packet->indicatrix2 & IND2_MIN)
		analog->mqflags |= SR_MQFLAG_MIN;
	if (rs_packet->info & INFO_AUTO)
		analog->mqflags |= SR_MQFLAG_AUTORANGE;

	*floatval = rawval;
	return SR_OK;
}
Commit	Line	Data
05f134ab	1	/*
50985c20	2	* This file is part of the libsigrok project.
05f134ab AG	3	*
	4	* Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com>
	5	*
	6	* This program is free software: you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation, either version 3 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	18	*/
	19
	20	/*
	21	* RadioShack 22-812 protocol parser.
	22	*
	23	* This protocol is currently encountered on the RadioShack 22-812 DMM.
	24	* It is a 9-byte packet representing a 1:1 mapping of the LCD segments, hence
	25	* the name rs9lcd.
	26	*
	27	* The chip is a bare die covered by a plastic blob. It is unclear if this chip
	28	* and protocol is used on any other device.
	29	*/
	30
	31	#include <string.h>
	32	#include <ctype.h>
	33	#include <math.h>
	34	#include <glib.h>
c1aae900	35	#include <libsigrok/libsigrok.h>
05f134ab AG	36	#include "libsigrok-internal.h"
05f134ab AG	37
b95dd761	38	#define LOG_PREFIX "rs9lcd"
05f134ab AG	39
05f134ab AG	40	/* Byte 1 of the packet, and the modes it represents */
0853d5e6 AG	41	#define IND1_HZ (1 << 7)
	42	#define IND1_OHM (1 << 6)
	43	#define IND1_KILO (1 << 5)
	44	#define IND1_MEGA (1 << 4)
	45	#define IND1_FARAD (1 << 3)
	46	#define IND1_AMP (1 << 2)
	47	#define IND1_VOLT (1 << 1)
	48	#define IND1_MILI (1 << 0)
05f134ab	49	/* Byte 2 of the packet, and the modes it represents */
0853d5e6 AG	50	#define IND2_MICRO (1 << 7)
	51	#define IND2_NANO (1 << 6)
	52	#define IND2_DBM (1 << 5)
	53	#define IND2_SEC (1 << 4)
	54	#define IND2_DUTY (1 << 3)
	55	#define IND2_HFE (1 << 2)
	56	#define IND2_REL (1 << 1)
	57	#define IND2_MIN (1 << 0)
05f134ab	58	/* Byte 7 of the packet, and the modes it represents */
0853d5e6 AG	59	#define INFO_BEEP (1 << 7)
	60	#define INFO_DIODE (1 << 6)
	61	#define INFO_BAT (1 << 5)
	62	#define INFO_HOLD (1 << 4)
	63	#define INFO_NEG (1 << 3)
	64	#define INFO_AC (1 << 2)
	65	#define INFO_RS232 (1 << 1)
	66	#define INFO_AUTO (1 << 0)
05f134ab	67	/* Instead of a decimal point, digit 4 carries the MAX flag */
0853d5e6	68	#define DIG4_MAX (1 << 3)
05f134ab	69	/* Mask to remove the decimal point from a digit */
0853d5e6	70	#define DP_MASK (1 << 3)
05f134ab AG	71
	72	/* What the LCD values represent */
	73	#define LCD_0 0xd7
	74	#define LCD_1 0x50
	75	#define LCD_2 0xb5
	76	#define LCD_3 0xf1
	77	#define LCD_4 0x72
	78	#define LCD_5 0xe3
	79	#define LCD_6 0xe7
	80	#define LCD_7 0x51
	81	#define LCD_8 0xf7
	82	#define LCD_9 0xf3
	83
	84	#define LCD_C 0x87
	85	#define LCD_E
	86	#define LCD_F
	87	#define LCD_h 0x66
	88	#define LCD_H 0x76
	89	#define LCD_I
	90	#define LCD_n
	91	#define LCD_P 0x37
	92	#define LCD_r
	93
	94	enum {
	95	MODE_DC_V = 0,
	96	MODE_AC_V = 1,
	97	MODE_DC_UA = 2,
	98	MODE_DC_MA = 3,
	99	MODE_DC_A = 4,
	100	MODE_AC_UA = 5,
	101	MODE_AC_MA = 6,
	102	MODE_AC_A = 7,
	103	MODE_OHM = 8,
	104	MODE_FARAD = 9,
	105	MODE_HZ = 10,
0853d5e6 AG	106	MODE_VOLT_HZ = 11, /* Dial set to V, Hz selected by Hz button */
0853d5e6 AG	107	MODE_AMP_HZ = 12, /* Dial set to A, Hz selected by Hz button */
05f134ab	108	MODE_DUTY = 13,
0853d5e6 AG	109	MODE_VOLT_DUTY = 14, /* Dial set to V, duty cycle selected */
0853d5e6 AG	110	MODE_AMP_DUTY = 15, /* Dial set to A, duty cycle selected */
05f134ab	111	MODE_WIDTH = 16,
0853d5e6 AG	112	MODE_VOLT_WIDTH = 17, /* Dial set to V, pulse width selected */
0853d5e6 AG	113	MODE_AMP_WIDTH = 18, /* Dial set to A, pulse width selected */
05f134ab AG	114	MODE_DIODE = 19,
	115	MODE_CONT = 20,
	116	MODE_HFE = 21,
	117	MODE_LOGIC = 22,
	118	MODE_DBM = 23,
0853d5e6	119	/* MODE_EF = 24, / / Not encountered on any DMM */
05f134ab AG	120	MODE_TEMP = 25,
	121	MODE_INVALID = 26,
	122	};
	123
	124	enum {
	125	READ_ALL,
	126	READ_TEMP,
	127	};
	128
	129	struct rs9lcd_packet {
	130	uint8_t mode;
	131	uint8_t indicatrix1;
	132	uint8_t indicatrix2;
	133	uint8_t digit4;
	134	uint8_t digit3;
	135	uint8_t digit2;
	136	uint8_t digit1;
	137	uint8_t info;
	138	uint8_t checksum;
	139	};
	140
	141	static gboolean checksum_valid(const struct rs9lcd_packet *rs_packet)
	142	{
	143	uint8_t *raw;
	144	uint8_t sum = 0;
	145	int i;
	146
	147	raw = (void *)rs_packet;
	148
21829e67	149	for (i = 0; i < RS9LCD_PACKET_SIZE - 1; i++)
05f134ab AG	150	sum += raw[i];
	151
	152	/* This is just a funky constant added to the checksum. */
	153	sum += 57;
	154	sum -= rs_packet->checksum;
	155	return (sum == 0);
	156	}
	157
	158	static gboolean selection_good(const struct rs9lcd_packet *rs_packet)
	159	{
	160	int count;
	161
	162	/* Does the packet have more than one multiplier? */
	163	count = 0;
	164	count += (rs_packet->indicatrix1 & IND1_KILO) ? 1 : 0;
	165	count += (rs_packet->indicatrix1 & IND1_MEGA) ? 1 : 0;
	166	count += (rs_packet->indicatrix1 & IND1_MILI) ? 1 : 0;
	167	count += (rs_packet->indicatrix2 & IND2_MICRO) ? 1 : 0;
	168	count += (rs_packet->indicatrix2 & IND2_NANO) ? 1 : 0;
	169	if (count > 1) {
ec5186f9	170	sr_dbg("More than one multiplier detected in packet.");
05f134ab AG	171	return FALSE;
	172	}
	173
	174	/* Does the packet "measure" more than one type of value? */
	175	count = 0;
	176	count += (rs_packet->indicatrix1 & IND1_HZ) ? 1 : 0;
	177	count += (rs_packet->indicatrix1 & IND1_OHM) ? 1 : 0;
	178	count += (rs_packet->indicatrix1 & IND1_FARAD) ? 1 : 0;
	179	count += (rs_packet->indicatrix1 & IND1_AMP) ? 1 : 0;
	180	count += (rs_packet->indicatrix1 & IND1_VOLT) ? 1 : 0;
	181	count += (rs_packet->indicatrix2 & IND2_DBM) ? 1 : 0;
	182	count += (rs_packet->indicatrix2 & IND2_SEC) ? 1 : 0;
	183	count += (rs_packet->indicatrix2 & IND2_DUTY) ? 1 : 0;
	184	count += (rs_packet->indicatrix2 & IND2_HFE) ? 1 : 0;
	185	if (count > 1) {
ec5186f9	186	sr_dbg("More than one measurement type detected in packet.");
05f134ab AG	187	return FALSE;
	188	}
	189
	190	return TRUE;
	191	}
	192
	193	/*
	194	* Since the 22-812 does not identify itself in any way, shape, or form,
	195	* we really don't know for sure who is sending the data. We must use every
	196	* possible check to filter out bad packets, especially since detection of the
	197	* 22-812 depends on how well we can filter the packets.
	198	*/
	199	SR_PRIV gboolean sr_rs9lcd_packet_valid(const uint8_t *buf)
	200	{
	201	const struct rs9lcd_packet rs_packet = (void )buf;
	202
	203	/*
	204	* Check for valid mode first, before calculating the checksum. No
	205	* point calculating the checksum, if we know we'll reject the packet.
	206	*/
	207	if (!(rs_packet->mode < MODE_INVALID))
	208	return FALSE;
	209
	210	if (!checksum_valid(rs_packet)) {
	211	sr_spew("Packet with invalid checksum. Discarding.");
	212	return FALSE;
	213	}
	214
	215	if (!selection_good(rs_packet)) {
	216	sr_spew("Packet with invalid selection bits. Discarding.");
	217	return FALSE;
	218	}
	219
	220	return TRUE;
	221	}
	222
	223	static uint8_t decode_digit(uint8_t raw_digit)
	224	{
	225	/* Take out the decimal point, so we can use a simple switch(). */
	226	raw_digit &= ~DP_MASK;
	227
	228	switch (raw_digit) {
	229	case 0x00:
	230	case LCD_0:
	231	return 0;
	232	case LCD_1:
	233	return 1;
	234	case LCD_2:
	235	return 2;
	236	case LCD_3:
	237	return 3;
	238	case LCD_4:
	239	return 4;
	240	case LCD_5:
	241	return 5;
	242	case LCD_6:
	243	return 6;
	244	case LCD_7:
	245	return 7;
	246	case LCD_8:
	247	return 8;
	248	case LCD_9:
	249	return 9;
	250	default:
ec5186f9	251	sr_dbg("Invalid digit byte: 0x%02x.", raw_digit);
05f134ab AG	252	return 0xff;
	253	}
	254	}
	255
	256	static double lcd_to_double(const struct rs9lcd_packet *rs_packet, int type)
	257	{
6e9d545c	258	double rawval = 0, multiplier = 1;
05f134ab AG	259	uint8_t digit, raw_digit;
	260	gboolean dp_reached = FALSE;
	261	int i, end;
	262
	263	/* end = 1: Don't parse last digit. end = 0: Parse all digits. */
	264	end = (type == READ_TEMP) ? 1 : 0;
	265
	266	/* We have 4 digits, and we start from the most significant. */
	267	for (i = 3; i >= end; i--) {
	268	raw_digit = *(&(rs_packet->digit4) + i);
	269	digit = decode_digit(raw_digit);
	270	if (digit == 0xff) {
	271	rawval = NAN;
	272	break;
	273	}
	274	/*
	275	* Digit 1 does not have a decimal point. Instead, the decimal
	276	* point is used to indicate MAX, so we must avoid testing it.
	277	*/
	278	if ((i < 3) && (raw_digit & DP_MASK))
	279	dp_reached = TRUE;
	280	if (dp_reached)
	281	multiplier /= 10;
	282	rawval = rawval * 10 + digit;
	283	}
	284	rawval *= multiplier;
	285	if (rs_packet->info & INFO_NEG)
	286	rawval *= -1;
	287
	288	/* See if we need to multiply our raw value by anything. */
	289	if (rs_packet->indicatrix1 & IND2_NANO)
	290	rawval *= 1E-9;
	291	else if (rs_packet->indicatrix2 & IND2_MICRO)
	292	rawval *= 1E-6;
	293	else if (rs_packet->indicatrix1 & IND1_MILI)
	294	rawval *= 1E-3;
	295	else if (rs_packet->indicatrix1 & IND1_KILO)
	296	rawval *= 1E3;
	297	else if (rs_packet->indicatrix1 & IND1_MEGA)
	298	rawval *= 1E6;
	299
	300	return rawval;
	301	}
	302
	303	static gboolean is_celsius(const struct rs9lcd_packet *rs_packet)
	304	{
	305	return ((rs_packet->digit4 & ~DP_MASK) == LCD_C);
	306	}
	307
	308	static gboolean is_shortcirc(const struct rs9lcd_packet *rs_packet)
	309	{
	310	return ((rs_packet->digit2 & ~DP_MASK) == LCD_h);
	311	}
	312
	313	static gboolean is_logic_high(const struct rs9lcd_packet *rs_packet)
	314	{
	315	sr_spew("Digit 2: 0x%02x.", rs_packet->digit2 & ~DP_MASK);
	316	return ((rs_packet->digit2 & ~DP_MASK) == LCD_H);
	317	}
	318
	319	SR_PRIV int sr_rs9lcd_parse(const uint8_t buf, float floatval,
	320	struct sr_datafeed_analog analog, void info)
	321	{
	322	const struct rs9lcd_packet rs_packet = (void )buf;
323	double rawval;
324
325	(void)info;
326
327	rawval = lcd_to_double(rs_packet, READ_ALL);
328
329	switch (rs_packet->mode) {
330	case MODE_DC_V:
331	analog->mq = SR_MQ_VOLTAGE;
332	analog->unit = SR_UNIT_VOLT;
333	analog->mqflags \|= SR_MQFLAG_DC;
334	break;
335	case MODE_AC_V:
336	analog->mq = SR_MQ_VOLTAGE;
337	analog->unit = SR_UNIT_VOLT;
338	analog->mqflags \|= SR_MQFLAG_AC;
339	break;
0853d5e6 AG	340	case MODE_DC_UA: /* Fall through */
0853d5e6 AG	341	case MODE_DC_MA: /* Fall through */
05f134ab AG	342	case MODE_DC_A:
	343	analog->mq = SR_MQ_CURRENT;
	344	analog->unit = SR_UNIT_AMPERE;
	345	analog->mqflags \|= SR_MQFLAG_DC;
	346	break;
0853d5e6 AG	347	case MODE_AC_UA: /* Fall through */
0853d5e6 AG	348	case MODE_AC_MA: /* Fall through */
05f134ab AG	349	case MODE_AC_A:
	350	analog->mq = SR_MQ_CURRENT;
	351	analog->unit = SR_UNIT_AMPERE;
	352	analog->mqflags \|= SR_MQFLAG_AC;
	353	break;
	354	case MODE_OHM:
	355	analog->mq = SR_MQ_RESISTANCE;
	356	analog->unit = SR_UNIT_OHM;
	357	break;
	358	case MODE_FARAD:
	359	analog->mq = SR_MQ_CAPACITANCE;
	360	analog->unit = SR_UNIT_FARAD;
	361	break;
	362	case MODE_CONT:
	363	analog->mq = SR_MQ_CONTINUITY;
	364	analog->unit = SR_UNIT_BOOLEAN;
47eda193	365	rawval = is_shortcirc(rs_packet);
05f134ab AG	366	break;
	367	case MODE_DIODE:
	368	analog->mq = SR_MQ_VOLTAGE;
	369	analog->unit = SR_UNIT_VOLT;
	370	analog->mqflags \|= SR_MQFLAG_DIODE \| SR_MQFLAG_DC;
	371	break;
0853d5e6 AG	372	case MODE_HZ: /* Fall through */
0853d5e6 AG	373	case MODE_VOLT_HZ: /* Fall through */
05f134ab AG	374	case MODE_AMP_HZ:
	375	analog->mq = SR_MQ_FREQUENCY;
	376	analog->unit = SR_UNIT_HERTZ;
	377	break;
	378	case MODE_LOGIC:
	379	/*
	380	* No matter whether or not we have an actual voltage reading,
	381	* we are measuring voltage, so we set our MQ as VOLTAGE.
	382	*/
	383	analog->mq = SR_MQ_VOLTAGE;
	384	if (!isnan(rawval)) {
	385	/* We have an actual voltage. */
	386	analog->unit = SR_UNIT_VOLT;
	387	} else {
	388	/* We have either HI or LOW. */
	389	analog->unit = SR_UNIT_BOOLEAN;
47eda193	390	rawval = is_logic_high(rs_packet);
05f134ab AG	391	}
	392	break;
	393	case MODE_HFE:
	394	analog->mq = SR_MQ_GAIN;
	395	analog->unit = SR_UNIT_UNITLESS;
	396	break;
0853d5e6 AG	397	case MODE_DUTY: /* Fall through */
0853d5e6 AG	398	case MODE_VOLT_DUTY: /* Fall through */
05f134ab AG	399	case MODE_AMP_DUTY:
	400	analog->mq = SR_MQ_DUTY_CYCLE;
	401	analog->unit = SR_UNIT_PERCENTAGE;
	402	break;
0853d5e6 AG	403	case MODE_WIDTH: /* Fall through */
0853d5e6 AG	404	case MODE_VOLT_WIDTH: /* Fall through */
05f134ab AG	405	case MODE_AMP_WIDTH:
	406	analog->mq = SR_MQ_PULSE_WIDTH;
	407	analog->unit = SR_UNIT_SECOND;
cbc8cbd8	408	break;
05f134ab AG	409	case MODE_TEMP:
	410	analog->mq = SR_MQ_TEMPERATURE;
	411	/* We need to reparse. */
47eda193	412	rawval = lcd_to_double(rs_packet, READ_TEMP);
05f134ab AG	413	analog->unit = is_celsius(rs_packet) ?
	414	SR_UNIT_CELSIUS : SR_UNIT_FAHRENHEIT;
	415	break;
	416	case MODE_DBM:
	417	analog->mq = SR_MQ_POWER;
	418	analog->unit = SR_UNIT_DECIBEL_MW;
	419	analog->mqflags \|= SR_MQFLAG_AC;
	420	break;
	421	default:
ec5186f9	422	sr_dbg("Unknown mode: %d.", rs_packet->mode);
05f134ab AG	423	break;
	424	}
	425
	426	if (rs_packet->info & INFO_HOLD)
	427	analog->mqflags \|= SR_MQFLAG_HOLD;
	428	if (rs_packet->digit4 & DIG4_MAX)
	429	analog->mqflags \|= SR_MQFLAG_MAX;
	430	if (rs_packet->indicatrix2 & IND2_MIN)
	431	analog->mqflags \|= SR_MQFLAG_MIN;
	432	if (rs_packet->info & INFO_AUTO)
	433	analog->mqflags \|= SR_MQFLAG_AUTORANGE;
	434
	435	*floatval = rawval;
	436	return SR_OK;
	437	}