Buffer Descriptors and Connection Tables
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
37-9
0x00
(cont.)
13
ICNG
Invert CNG (AAL5 only). Valid only when the current BD is the first BD of an
AAL5 frame. The ICNG mechanism allows the dynamic modification of the CNG
bit in the channel’s ATM cell header per frame. Setting ICNG instructs the CP to
invert (flip) the middle bit of the PTI (congestion indication) in TCT[CHEAD]. The
change takes effect immediately (starting from the first cell of this frame).
TxBD[ICNG] is cleared by the CP when the buffer is closed.
0 Do not invert the CNG bit in TCT[CHEAD].
1 Invert the CNG bit in TCT[CHEAD].
Note that for cases in which the mechanisms conflict, the ICNG mechanism is
applied after the RH mechanism.
14
RH
Replace header (AAL5 only). Valid only when the current BD is the first BD of
an AAL5 frame. The RH mechanism allows the dynamic modification of the
channel’s ATM cell header per frame. Setting RH instructs the CP to copy the
contents of the TxBD[HEADER] field into TCT[CHEAD], and then clear
TxBD[HEADER]. The header replacement takes effect immediately (starting
from the first cell of this frame). TxBD[RH] is cleared by the CP when the buffer
is closed.
When the RH bit is set, the CPCS-UU and CPI field in the TxBD is not available
because the 16 bits are used as the lower order half of the HEADER field. The
transmitter sends a dummy field of all zeros for the CPCS-UU and CPI field.
The RH mechanism can be used to implement a global AAL5 queue for different
VC/VP. It can also be used for frame relay to ATM CLP and EFCI interoperability.
0 Do not replace TCT[CHEAD].
1 Copy TxBD[HEADER] into TCT[CHEAD], and then clear TxBD[HEADER].
15
ICLP
Invert CLP (AAL5 only). Valid only when the current BD is the first BD of an
AAL5 frame. The ICLP mechanism allows the dynamic modification of the CLP
bit in the channel’s ATM cell header per frame. Setting ICLP instructs the CP to
invert (flip) the CLP bit in TCT[CHEAD]. The change takes effect immediately
(starting from the first cell of this frame). TxBD[ICLP] is cleared by the CP when
the buffer is closed.
0 Do not invert the CLP bit in TCT[CHEAD].
1 Invert the CLP bit in TCT[CHEAD].
Note that for cases in which the mechanisms conflict, the ICLP mechanism is
applied after the RH mechanism.
0x02
—
Data length
Specifies the number of octets the ATM controller sends from this BD’s data
buffer. The value of data length should follow the guidelines in
Section 37.1.1,
“AAL5 Buffers,”
or
Section 37.1.2, “AAL0 Buffers,”
as appropriate. This value is
not modified by the CP.
0x04
—
Transmit data
buffer pointer
Contains the address of the associated data buffer. The buffer may reside in
either internal or external memory. This value is not modified by the CP.
Table 37-2. ATM TxBD Field Descriptions (continued)
Offset from
TBD_PTR
Bits
Name
Description
Содержание PowerQUICC MPC870
Страница 1: ...MPC885 PowerQUICC Family Reference Manual Supports MPC885 MPC880 MPC875 MPC870 MPC885RM Rev 2 04 2006 ...
Страница 98: ...MPC885 PowerQUICC Family Reference Manual Rev 2 I 4 Freescale Semiconductor ...
Страница 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Страница 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Страница 192: ...MPC885 Instruction Set MPC885 PowerQUICC Family Reference Manual Rev 2 5 22 Freescale Semiconductor ...
Страница 242: ...Instruction and Data Caches MPC885 PowerQUICC Family Reference Manual Rev 2 7 30 Freescale Semiconductor ...
Страница 288: ...MPC885 PowerQUICC Family Reference Manual Rev 2 III 4 Freescale Semiconductor ...
Страница 416: ...External Bus Interface MPC885 PowerQUICC Family Reference Manual Rev 2 13 42 Freescale Semiconductor ...
Страница 440: ...Clocks and Power Control MPC885 PowerQUICC Family Reference Manual Rev 2 14 24 Freescale Semiconductor ...
Страница 554: ...MPC885 PowerQUICC Family Reference Manual Rev 2 V 6 Freescale Semiconductor ...
Страница 606: ...SDMA Channels and IDMA Emulation MPC885 PowerQUICC Family Reference Manual Rev 2 19 20 Freescale Semiconductor ...
Страница 738: ...SCC Asynchronous HDLC Mode and IrDA MPC885 PowerQUICC Family Reference Manual Rev 2 25 16 Freescale Semiconductor ...
Страница 780: ...SCC Ethernet Mode MPC885 PowerQUICC Family Reference Manual Rev 2 27 24 Freescale Semiconductor ...
Страница 794: ...SCC Transparent Mode MPC885 PowerQUICC Family Reference Manual Rev 2 28 14 Freescale Semiconductor ...
Страница 848: ...Serial Peripheral Interface SPI MPC885 PowerQUICC Family Reference Manual Rev 2 30 18 Freescale Semiconductor ...
Страница 882: ...Universal Serial Bus USB MPC885 PowerQUICC Family Reference Manual Rev 2 31 34 Freescale Semiconductor ...
Страница 944: ...Parallel I O Ports MPC885 PowerQUICC Family Reference Manual Rev 2 34 26 Freescale Semiconductor ...
Страница 956: ...CPM Interrupt Controller MPC885 PowerQUICC Family Reference Manual Rev 2 35 12 Freescale Semiconductor ...
Страница 1004: ...Buffer Descriptors and Connection Tables MPC885 PowerQUICC Family Reference Manual Rev 2 37 30 Freescale Semiconductor ...
Страница 1022: ...ATM Parameter RAM MPC885 PowerQUICC Family Reference Manual Rev 2 38 18 Freescale Semiconductor ...
Страница 1068: ...ATM Pace Control MPC885 PowerQUICC Family Reference Manual Rev 2 40 22 Freescale Semiconductor ...
Страница 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Страница 1120: ...AAL2 Implementation MPC885 PowerQUICC Family Reference Manual Rev 2 44 30 Freescale Semiconductor ...
Страница 1162: ...Fast Ethernet Controller FEC MPC885 PowerQUICC Family Reference Manual Rev 2 45 40 Freescale Semiconductor ...
Страница 1172: ...SEC Lite Overview MPC885 PowerQUICC Family Reference Manual Rev 2 46 8 Freescale Semiconductor ...
Страница 1176: ...SEC Lite Address Map MPC885 PowerQUICC Family Reference Manual Rev 2 47 4 Freescale Semiconductor ...
Страница 1214: ...SEC Lite Execution Units MPC885 PowerQUICC Family Reference Manual Rev 2 48 38 Freescale Semiconductor ...
Страница 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
Страница 1313: ...MPC885 PowerQUICC Family Reference Manual Rev 2 Freescale Semiconductor B 1 Appendix B Serial Communications Performance TBD ...
Страница 1314: ...Serial Communications Performance MPC885 PowerQUICC Family Reference Manual Rev 2 B 2 Freescale Semiconductor ...
Страница 1320: ...Register Quick Reference Guide MPC885 PowerQUICC Family Reference Manual Rev 2 C 6 Freescale Semiconductor ...
Страница 1336: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 16 Freescale Semiconductor ...
Страница 1358: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 38 Freescale Semiconductor ...
Страница 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Страница 1384: ...Serial ATM Scrambling Reception and SI Programming MPC885 PowerQUICC Family Reference Manual Rev 2 H 6 Freescale Semiconductor ...
Страница 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...