fix(#19647): correction of fractional calculations
Altitude dissector added
This commit is contained in:
marmonier_c
AndersBroman
parent
ac9ff53c7a
commit
5e9e75537a
|
|
@ -1355,6 +1355,77 @@ media_power_base(gchar *buf, guint32 value) {
|
|||
snprintf(buf, ITEM_LABEL_LENGTH, "%u mW", value * 100);
|
||||
}
|
||||
|
||||
// Get absolute 2's complement value
|
||||
// Returns true if the value is negative (so if
|
||||
// it returns false, there is no conversion).
|
||||
// bitSize: number of bits of the variable.
|
||||
static gboolean
|
||||
get2sComplementAbsoluteValue(guint64 * value, guint bitSize){
|
||||
const guint64 signMask = G_GINT64_CONSTANT(0x1) << (bitSize - 1);
|
||||
|
||||
guint64 signedMask = G_GINT64_CONSTANT(0x1) << bitSize;
|
||||
signedMask--;
|
||||
signedMask = ~signedMask;
|
||||
|
||||
if(*value & signMask){
|
||||
*value |= signedMask; // sign propagation
|
||||
|
||||
// Convert to absolute value
|
||||
*value = ~(*value);
|
||||
(*value)++;
|
||||
return TRUE;
|
||||
}
|
||||
return FALSE;
|
||||
}
|
||||
|
||||
static guint64
|
||||
getUint64MaskedValue(guint64 value, guint bitSize){
|
||||
guint64 mask = G_GINT64_CONSTANT(0x1) << bitSize;
|
||||
mask--;
|
||||
return value & mask;
|
||||
}
|
||||
|
||||
static guint64
|
||||
pow10_uint64(gint exponent){
|
||||
guint64 val = 1;
|
||||
|
||||
while(exponent > 0){
|
||||
val *= 10;
|
||||
exponent--;
|
||||
}
|
||||
|
||||
while(exponent < 0){
|
||||
val /= 10;
|
||||
exponent++;
|
||||
}
|
||||
return val;
|
||||
}
|
||||
|
||||
// Decode uint fractionnal variable
|
||||
static guint64
|
||||
convertFractionalToFixedSizeDecimal(guint64 value, guint fractionnalBitSize, guint numberOfDigitToDisplay){
|
||||
const guint64 resolution = G_GINT64_CONSTANT(0x1) << fractionnalBitSize;
|
||||
// => 0x02000000 for 25-bits
|
||||
// => 0x00000100 for 8-bits
|
||||
|
||||
const guint64 fractionnalPortionMask = resolution - 1;
|
||||
value &= fractionnalPortionMask;
|
||||
|
||||
// Maximum value for numberOfDigitToDisplay is :
|
||||
// log10(G_GINT64_CONSTANT(0xFFFFFFFFFFFFFFFF) / fractionnalPortionMask);
|
||||
// => if result is stored in 32-bits, numberOfDigitToDisplay max = 9
|
||||
const guint64 displayMultiplier = pow10_uint64(numberOfDigitToDisplay);
|
||||
value *= displayMultiplier;
|
||||
guint64 moduloValue = value % resolution;
|
||||
value /= resolution;
|
||||
if(moduloValue >= (resolution/2)){
|
||||
value++; // rounded value
|
||||
}
|
||||
|
||||
return value;
|
||||
}
|
||||
|
||||
|
||||
/* Calculate Latitude and Longitude string */
|
||||
/*
|
||||
Parameters:
|
||||
|
|
@ -1364,54 +1435,57 @@ media_power_base(gchar *buf, guint32 value) {
|
|||
static void
|
||||
get_latitude_or_longitude(gchar *buf, int option, guint64 unmasked_value)
|
||||
{
|
||||
guint64 value = unmasked_value & G_GINT64_CONSTANT(0x03FFFFFFFF);
|
||||
guint64 tempValue = value;
|
||||
gboolean negativeNum = FALSE;
|
||||
guint32 integerPortion = 0;
|
||||
const char *direction;
|
||||
|
||||
/* The latitude and longitude are 34 bit fixed point value consisting
|
||||
of 9 bits of integer and 25 bits of fraction.
|
||||
When option is equal to 0, positive numbers are represent a location
|
||||
north of the equator and negative (2s complement) numbers are south of the equator.
|
||||
When option is equal to 1, positive values are east of the prime
|
||||
meridian and negative (2s complement) numbers are west of the prime meridian.
|
||||
Longitude values outside the range of -180 to 180 decimal degrees or latitude values
|
||||
outside the range of -90 to 90 degrees MUST be considered invalid.
|
||||
*/
|
||||
const guint variableBitSize = 34;
|
||||
const guint fractionnalBitSize = 25;
|
||||
|
||||
if (value & G_GINT64_CONSTANT(0x0000000200000000))
|
||||
{
|
||||
/* Have a negative number (2s complement) */
|
||||
negativeNum = TRUE;
|
||||
guint64 masked_value = getUint64MaskedValue(unmasked_value, variableBitSize); // get 34-bit value
|
||||
|
||||
tempValue = ~value;
|
||||
tempValue += 1;
|
||||
}
|
||||
// Get absoluste value of a 34-bit 2's variable
|
||||
// => value is 33-bit
|
||||
guint64 absolute_value = masked_value;
|
||||
gboolean isNegative = get2sComplementAbsoluteValue(&absolute_value, variableBitSize);
|
||||
|
||||
// Get unsigned integer 8-bit value
|
||||
guint32 integerPortion = absolute_value >> fractionnalBitSize;
|
||||
|
||||
/* Get the integer portion */
|
||||
integerPortion = (guint32)((tempValue & G_GINT64_CONSTANT(0x00000003FE000000)) >> 25);
|
||||
// Get fractionnal 25-bit value
|
||||
const guint numberOfDigitToDisplay = 4;
|
||||
guint64 fixedSizeDecimal = convertFractionalToFixedSizeDecimal(absolute_value, fractionnalBitSize, numberOfDigitToDisplay);
|
||||
|
||||
/* Calculate decimal portion (using 25 bits for fraction) */
|
||||
tempValue = (tempValue & G_GINT64_CONSTANT(0x0000000001FFFFFF))/33554432;
|
||||
|
||||
if (option == 0)
|
||||
{
|
||||
/* Latitude - north/south directions */
|
||||
if (negativeNum)
|
||||
const char *direction;
|
||||
if (option == 0){
|
||||
// Latitude - north/south directions
|
||||
if (isNegative){
|
||||
direction = "South";
|
||||
else
|
||||
} else {
|
||||
direction = "North";
|
||||
}
|
||||
else
|
||||
{
|
||||
/* Longitude - east/west directions */
|
||||
if (negativeNum)
|
||||
}
|
||||
} else {
|
||||
// Longitude - east/west directions
|
||||
if (isNegative){
|
||||
direction = "West";
|
||||
else
|
||||
} else {
|
||||
direction = "East";
|
||||
}
|
||||
}
|
||||
|
||||
snprintf(buf, ITEM_LABEL_LENGTH, "%u.%04" PRIu64 " degrees %s (0x%010" PRIX64 ")",
|
||||
integerPortion, tempValue, direction, value);
|
||||
const guint64 fractionalMask = (G_GINT64_CONSTANT(0x1) << fractionnalBitSize) - 1;
|
||||
|
||||
// %04 correspond to numberOfDigitToDisplay
|
||||
snprintf(buf, ITEM_LABEL_LENGTH, "%u.%04" PRIu64 " degrees %s (0x%010" PRIX64 " - %u-bit integer part 0x%04" PRIX64 " / %u-bit fractional part 0x%08" PRIX64 ")",
|
||||
integerPortion, fixedSizeDecimal, direction, masked_value,
|
||||
variableBitSize - fractionnalBitSize, masked_value >> fractionnalBitSize,
|
||||
fractionnalBitSize, masked_value & fractionalMask
|
||||
);
|
||||
}
|
||||
|
||||
static void
|
||||
|
|
@ -1424,6 +1498,74 @@ longitude_base(gchar *buf, guint64 value) {
|
|||
get_latitude_or_longitude(buf, 1, value);
|
||||
}
|
||||
|
||||
static void
|
||||
altitude_base(gchar *buf, guint32 unmasked_value) {
|
||||
// RFC6225
|
||||
// Altitude: A 30-bit value defined by the AType field.
|
||||
// In some cases, the altitude of the location might not be provided.
|
||||
// An Altitude Type value of zero indicates that the altitude is not
|
||||
// given to the client. In this case, the Altitude and Altitude
|
||||
// Uncertainty fields can contain any value and MUST be ignored.
|
||||
//
|
||||
// If the Altitude Type has a value of one, altitude is measured in
|
||||
// meters, in relation to the zero set by the vertical datum. For AType
|
||||
// = 1, the altitude value is expressed as a 30-bit, fixed-point, two's
|
||||
// complement integer with 22 integer bits and 8 fractional bits.
|
||||
//
|
||||
// A value of two for Altitude Type indicates that the altitude value is
|
||||
// measured in floors. Since altitude in meters may not be known within
|
||||
// a building, a floor indication may be more useful. For AType = 2,
|
||||
// the altitude value is expressed as a 30-bit, fixed-point, two's
|
||||
// complement integer with 22 integer bits and 8 fractional bits.
|
||||
//
|
||||
// the altitude resolution (AltRes) value encodes the number of
|
||||
// high-order altitude bits that should be considered valid.
|
||||
// Values above 30 (decimal) are undefined and reserved.
|
||||
//
|
||||
// The encoded altitude of 000000000000000010000110110011 decodes to
|
||||
// 33.69921875. The encoded uncertainty of 15 gives a value of 64;
|
||||
// therefore, the final uncertainty is 33.69921875 +/- 64 (or the range
|
||||
// from -30.30078125 to 97.69921875).
|
||||
// The amount of altitude uncertainty can be determined by the following
|
||||
// formula, where x is the encoded integer value:
|
||||
// Uncertainty = 2 ^ ( 21 - x )
|
||||
// = 2 ^ ( 21 - 15 ) = 2 ^ 6 = 64
|
||||
|
||||
const guint variableBitSize = 30;
|
||||
const guint fractionnalBitSize = 8;
|
||||
|
||||
guint64 masked_value = getUint64MaskedValue(unmasked_value, variableBitSize); // get 30-bit value
|
||||
|
||||
// Get absoluste value of a 30-bit 2's variable
|
||||
// => value is 29-bit
|
||||
guint64 absolute_value = masked_value;
|
||||
gboolean isNegative = get2sComplementAbsoluteValue(&absolute_value, variableBitSize);
|
||||
|
||||
// Get unsigned integer 8-bit value
|
||||
guint32 integerPortion = absolute_value >> fractionnalBitSize;
|
||||
|
||||
// Get fractionnal 8-bit value
|
||||
const guint numberOfDigitToDisplay = 4;
|
||||
guint64 fixedSizeDecimal = convertFractionalToFixedSizeDecimal(absolute_value, fractionnalBitSize, numberOfDigitToDisplay);
|
||||
|
||||
const char * sign;
|
||||
if (isNegative){
|
||||
sign = "-";
|
||||
} else {
|
||||
sign = "+";
|
||||
}
|
||||
|
||||
|
||||
const guint64 fractionalMask = (G_GINT64_CONSTANT(0x1) << fractionnalBitSize) - 1;
|
||||
|
||||
// %04 correspond to numberOfDigitToDisplay
|
||||
snprintf(buf, ITEM_LABEL_LENGTH, "%s%u.%04" PRIu64 " (0x%08" PRIX64 " - %u-bit integer part 0x%06" PRIX64 " / %u-bit fractional part 0x%02" PRIX64 ")",
|
||||
sign, integerPortion, fixedSizeDecimal, masked_value,
|
||||
variableBitSize - fractionnalBitSize, masked_value >> fractionnalBitSize,
|
||||
fractionnalBitSize, masked_value & fractionalMask
|
||||
);
|
||||
}
|
||||
|
||||
/* Dissect Chassis Id TLV (Mandatory) */
|
||||
static gint32
|
||||
dissect_lldp_chassis_id(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32 offset,
|
||||
|
|
@ -5861,8 +6003,8 @@ proto_register_lldp(void)
|
|||
NULL, 0x0FC0, NULL, HFILL }
|
||||
},
|
||||
{ &hf_media_loc_alt,
|
||||
{ "Altitude", "lldp.media.loc.altitude", FT_UINT32, BASE_DEC,
|
||||
NULL, 0x3FFFFFFF, NULL, HFILL }
|
||||
{ "Altitude", "lldp.media.loc.altitude", FT_UINT32, BASE_CUSTOM,
|
||||
CF_FUNC(altitude_base), 0x0, NULL, HFILL }
|
||||
},
|
||||
{ &hf_media_loc_datum,
|
||||
{ "Datum", "lldp.media.loc.datum", FT_UINT8, BASE_DEC,
|
||||
|
|
|
|||
Loading…
Reference in New Issue