AM79C978 Advanced Micro Devices, AM79C978 Datasheet - Page 250

• Manufacturer Part Number: AM79C978
• Description: Single-Chip 1/10 Mbps PCI Home Networking Controller
• Manufacturer: Advanced Micro Devices

B-10
Descriptor
Descriptor
Descriptor
Descriptor
Descriptor
Descriptor
Descriptor
Descriptor
Descriptor
#1
#2
#3
#4
#5
#6
#7
#8
#9
OWN = 1
SIZE = HEADER_SIZE (minimum 64 bytes)
OWN = 1
SIZE = S1+S2+S3+S4
OWN = 0
SIZE = 1518 - (S1+S2+S3+S4+HEADER_SIZE)
OWN = 1
SIZE = HEADER_SIZE (minimum 64 bytes)
OWN = 1
SIZE = S1+S2+S3+S4
OWN = 0
SIZE = 1518 - (S1+S2+S3+S4+HEADER_SIZE)
OWN = 1
SIZE = HEADER_SIZE (minimum 64 bytes)
OWN = 1
SIZE = S1+S2+S3+S4
OWN = 0
SIZE = 1518 - (S1+S2+S3+S4+HEADER_SIZE)
Figure B-4. LAPP 3 Buffer Grouping for Two-interrupt Method
STP = 0
STP = 0
STP = 1
STP = 0
STP = 0
STP = 1
STP = 0
STP = 0
Am79C978
STP = 1
Note that the times needed for tasks S1,
S2, S3, S4, and S6 should be divided by
0.8 microseconds to yield an equivalent
number of network byte times before
subtracting these quantities from the
expected message size A.
A = Expected message size in bytes
S1 = Interrupt latency
S2 = Application call latency
S3 = Time needed for driver to write
S4 = Time needed for driver to copy
S6 = Time needed for driver to copy
to third descriptor
data from buffer #1 to
application buffer space
data from buffer #2 to
application buffer space
22206B-B4