ATM Parameter RAM
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
38-13
The address match parameter configuration for extended channel mode with address compression
(SRSTATE[EXT, ACP] = 11) is shown in Table 38-10. See also
Section 39.1.2, “Address Compression
(SRSTATE[EXT,ACP] = 11).”
FLMASK is shown in
Figure 38-6
.
The FLMASK fields are described in
Table 38-11
.
The address match parameter configuration for extended channel mode CAM operation
(SRSTATE[EXT,ACP] = 10) is shown in
Table 38-12
. See also the discussion in
Section 39.1.3, “CAM
Address Mapping (SRSTATE[EXT,ACP] = 10).”
Table 38-10. AM1–AM5 Parameters
for Extended Channel Address Compression
Field
Name
Function
AM1
FLBASE First-level table base. Contains the word-aligned starting address for the first-level table of the
address compression mechanism.
AM2
AM3
SLBASE Second-level table base. Pointer to the word-aligned beginning of a 64-Kbyte memory space where
the set of second-level addressing tables are located. Bit 31 of SLBASE, if set, enables scaling of
Second-level offsets (SLTOFFSET values) by a factor of 4 before adding them to SLBASE.
AM4
AM5
FLMASK First-level mask. The ATM controller masks the GFC, VPI, and PTI bits of the header of each
incoming cell with FLMASK[1–15] and uses the resulting masked header in the first-level address
matching process. The masking process uses a bitwise AND function to allow address bits to be
masked out by clearing the relevant bits in FLMASK. The FLMASK fields are shown in
Figure 38-6
.
The FLMASK should contain an unbroken sequence of ones. For example, the sequence
0b0000_0011_1111_1110 would be a valid sequence, while the sequence
0b0000_1111_1001_1100 contains a broken sequence of ones and would lead to undefined
behavior during the matching process.
0
1
4
5
12
13
15
CUMB
GFC
VPI
PTI
Figure 38-6. FLMASK
Table 38-11. FLMASK Field Descriptions
Bit(s)
Name
Description
0
CUMB Check unused mask bits. CUMB allows the user to screen out (pass to the global raw cell queue)
misinserted cells. Setting CUMB signals the receiver to check for non-zero values in the address
bits not used during the address matching. See
Section 39.1.2.4, “Preventing Channel Aliasing.”
0 Do not check unused address bits.
1 Check that all unused address bits equal 0.
1–4
GFC
Generic flow control mask. Can be cleared when the GFC protocol is not enforced.
5–12
VPI
Virtual path identifier mask
13–15
PTI
Payload type identifier mask
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