AXIS5Packet Class

AXIS5Packet is AXISPacket plus the AMBA5 fields: a wakeup bit, per-byte parity, and a parity_error flag for recording check results. This page also covers AXIS5Transaction, the randomized generator that produces these packets.

Key Differences from AXIS4 Packet

• Added fields: wakeup (1 bit), parity (1 bit per data byte), parity_error (1 bit)
• Parity support: automatic per-byte odd parity calculation and verification, per the AMBA AXI5-Stream TPARITY convention
• Wakeup support: the wake-up signal state travels with the packet
• Backward compatibility: all AXIS4 fields (data, strb, last, id, dest, user) are unchanged
• Conversion: to_axis4_packet() drops the AXIS5 extras when you need a plain AXIS4 packet

AXIS5Packet

Class Signature

class AXIS5Packet(AXISPacket):
    def __init__(self, field_config=None, skip_compare_fields=None,
                 data_width=32, enable_wakeup=True, enable_parity=False, **kwargs)

Constructor Parameters

Parameter	Type	Description	Default
field_config	FieldConfig	Field configuration (auto-created if None)	None
skip_compare_fields	List[str]	Fields to skip in packet comparison	['start_time', 'end_time', 'count', 'parity_error']
data_width	int	Data width in bits	32
enable_wakeup	bool	Enable wakeup signal field	True
enable_parity	bool	Enable parity signal field	False
**kwargs	Any	Initial field values	--

Static Methods

create_axis5_field_config(data_width, id_width, dest_width, user_width, enable_wakeup, enable_parity) -> FieldConfig

Builds a field configuration for AXIS5 packets.

Parameter	Type	Description	Default
data_width	int	Data width in bits	32
id_width	int	ID width in bits	8
dest_width	int	Destination width in bits	4
user_width	int	User width in bits	1
enable_wakeup	bool	Enable wakeup field	True
enable_parity	bool	Enable parity field	False

Returns: FieldConfig with the following fields:

Field	Bits	Description	Condition
data	data_width	Stream data	Always
strb	data_width/8	Byte strobes	Always
last	1	Last transfer indicator	Always
id	id_width	Stream ID	id_width > 0
dest	dest_width	Destination	dest_width > 0
user	user_width	User signal	user_width > 0
wakeup	1	Wake-up signal	enable_wakeup
parity	data_width/8	Data parity (1 bit per byte)	enable_parity
parity_error	1	Parity error indicator	enable_parity

Properties

Property	Type	Description
wakeup	int	Wake-up signal value (0 or 1)
parity	int	Parity value (bit per byte)
parity_error	int	Parity error indicator (0 or 1)

Key Methods

calculate_parity() -> int

The expected TPARITY for the current data field value: per-byte odd parity, one parity bit per data byte, matching the AMBA AXI5-Stream specification.

Returns: Calculated parity value.

Algorithm: For each byte of data, count the set bits. The parity bit is chosen so the byte plus its parity bit carry an odd total number of ones — it is the inverted XOR of the byte's bits (0 when the byte already has an odd number of ones, 1 when it has an even number). The standalone helper calculate_odd_parity(data_value, num_bytes) (exported from axis5_packet) does the same math and is reused by the slave and monitor.

check_parity() -> bool

Compares the stored parity against the calculated odd parity for the current data.

Returns: True if parity is correct (or parity is disabled), False on mismatch.

copy() -> AXIS5Packet

Copies the packet. Unlike the base Packet.copy(), this override keeps the AXIS5 constructor options (data_width, enable_wakeup, enable_parity) along with all field values and timing. That matters for parity: copy a packet whose parity was deliberately corrupted and the copy still reports check_parity() == False, because it keeps enable_parity enabled.

set_wakeup(enable=True)

Sets the wakeup signal state.

Parameter	Type	Description	Default
enable	bool	True to assert wakeup	True

is_wakeup_active() -> bool

True if wakeup is asserted in this packet.

to_axis4_packet() -> AXISPacket

Converts to an AXIS4 packet by dropping the AXIS5-specific fields (wakeup, parity, parity_error).

Returns: AXISPacket with the core fields copied over.

Usage Examples

Example 1: Basic Packet Creation

from CocoTBFramework.components.axis5 import AXIS5Packet

# Create packet with wakeup only
pkt = AXIS5Packet(data_width=32, enable_wakeup=True, enable_parity=False)
pkt.data = 0xDEADBEEF
pkt.strb = 0xF
pkt.last = 1
pkt.id = 5
pkt.dest = 2
pkt.wakeup = 1

print(pkt)
# AXIS5 Packet:
#   Data:     0xDEADBEEF
#   Strobe:   0b1111
#   Last:     1
#   ID:       0x5
#   Dest:     0x2
#   User:     0x0
#   Wakeup:   1

Example 2: Parity Calculation and Checking

# Create packet with parity enabled
pkt = AXIS5Packet(data_width=32, enable_wakeup=False, enable_parity=True)
pkt.data = 0x12345678

# Auto-calculate parity
pkt.parity = pkt.calculate_parity()
print(f"Parity: 0b{pkt.parity:04b}")

# Verify parity
assert pkt.check_parity() is True

# Corrupt data and re-check
pkt.data = 0x12345679  # Changed last byte
assert pkt.check_parity() is False  # Parity no longer matches

Example 3: Conversion to AXIS4

# Create AXIS5 packet
axis5_pkt = AXIS5Packet(
    data_width=64, enable_wakeup=True, enable_parity=True
)
axis5_pkt.data = 0xCAFEBABEDEADBEEF
axis5_pkt.last = 1
axis5_pkt.id = 3
axis5_pkt.wakeup = 1
axis5_pkt.parity = axis5_pkt.calculate_parity()

# Convert to AXIS4 (drops wakeup and parity)
axis4_pkt = axis5_pkt.to_axis4_packet()
assert axis4_pkt.data == 0xCAFEBABEDEADBEEF
assert axis4_pkt.id == 3
assert not hasattr(axis4_pkt, 'wakeup')  # AXIS5 field removed

---

AXIS5Transaction

A randomized generator for AXIS5 traffic — call next() and it hands you packets, so you don't have to hand-write each one.

Class Signature

class AXIS5Transaction:
    def __init__(self, data_width=32, id_width=8, dest_width=4, user_width=1,
                 enable_wakeup=True, enable_parity=False, randomizer=None)

Constructor Parameters

Parameter	Type	Description	Default
data_width	int	Data width in bits	32
id_width	int	ID width in bits	8
dest_width	int	Destination width in bits	4
user_width	int	User width in bits	1
enable_wakeup	bool	Enable wakeup randomization	True
enable_parity	bool	Enable parity generation	False
randomizer	FlexRandomizer or dict	Optional randomizer for value generation	None

When no randomizer is provided, a default FlexRandomizer is created with: - data: Full range random - strb: All bytes enabled - last: 75% not-last, 25% last - id, dest, user: Full range random - wakeup: 90% inactive, 10% active

Key Methods

next() -> AXIS5Packet

Generates the next random transaction packet. If parity is enabled, it's calculated automatically.

Returns: New AXIS5Packet with randomized values.

create_packet(data, last=0, id=0, dest=0, user=0, wakeup=0, strb=None) -> AXIS5Packet

Builds a packet with specific values instead of random ones — the directed-test counterpart to next().

Parameter	Type	Description	Default
data	int	Data value	(required)
last	int	Last transfer flag	0
id	int	Stream ID	0
dest	int	Destination	0
user	int	User signal	0
wakeup	int	Wakeup signal	0
strb	int	Strobe value (full strobe if None)	None

Returns: AXIS5Packet with the specified values and auto-calculated parity (if enabled).

Usage Examples

from CocoTBFramework.components.axis5 import AXIS5Transaction

# Example 1: Random transaction generation
txn_gen = AXIS5Transaction(
    data_width=32, enable_wakeup=True, enable_parity=True
)

# Generate 10 random packets
packets = [txn_gen.next() for _ in range(10)]
for pkt in packets:
    print(f"data=0x{pkt.data:08X}, last={pkt.last}, wakeup={pkt.wakeup}")

# Example 2: Specific packet creation
txn_gen = AXIS5Transaction(data_width=64, enable_parity=True)

pkt = txn_gen.create_packet(
    data=0x1122334455667788,
    last=1, id=3, dest=1, wakeup=0
)
assert pkt.check_parity() is True

# Example 3: Custom randomizer
from CocoTBFramework.components.shared.flex_randomizer import FlexRandomizer

custom_rand = FlexRandomizer({
    'data': ([(0, 0xFF)], [1]),           # Small data values
    'strb': ([(0xF, 0xF)], [1]),          # Full strobe
    'last': ([(0, 0), (1, 1)], [1, 1]),   # 50/50 last
    'id': ([(0, 3)], [1]),                # 4 stream IDs
    'dest': ([(0, 0)], [1]),              # Single destination
    'user': ([(0, 0)], [1]),              # No user data
    'wakeup': ([(0, 0), (1, 1)], [4, 1]),  # 20% wakeup
})

txn_gen = AXIS5Transaction(
    data_width=32, enable_wakeup=True,
    enable_parity=True, randomizer=custom_rand
)