29-68
MPC8260 PowerQUICC II UserÕs Manual
MOTOROLA
Part IV. Communications Processor Module
Table 29-32 describes free buffer pool entry Þelds.
29.10.5.2.4 Free Buffer Pool Parameter Tables
The free buffer pool parameters are held in parameter tables in the dual-port RAM; see
Table 29-33. FBT_BASE in the parameter RAM points to the base address of these tables.
Each of the four free buffer pools has its own parameter table with a starting address given
by F RCT[BPOOL]
´
16.
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0x00
V
Ñ
W
I
Buffer Pointer (BP)
0x02
Buffer Pointer (BP)
Figure 29-45. Free Buffer Pool Entry
Table 29-32. Free Buffer Pool Entry Field Descriptions
Offset
Bits
Name
Description
0x00
0
V
Valid buffer entry.
0 This free buffer pool entry contains an invalid buffer pointer.
1 This free buffer pool entry contains a valid buffer pointer.
1
Ñ
Reserved, should be cleared.
2
W
Wrap bit. When set, this bit indicates the last entry in the circular table. During initialization,
the host must clear all W bits in the table except the last one, which must be set.
3
I
Red-line interrupt. Can be used to indicate that the free buffer pool has reached a red line and
additional buffers should be added to this pool to avoid a busy condition.
0 No interrupt is generated.
1 A red-line interrupt is generated when this buffer is fetched from the free buffer pool.
4Ð15
BP
Buffer pointer. Points to the start address of the receive buffer. The four msbs are control bits,
and the four msbs of the real buffer pointer are taken from the four msbs of the parameter
FBP_ENTRY_EXT in the free buffer pool parameter table.
0x02
0Ð15
Table 29-33. Free Buffer Pool Parameter Table
Offset
1
Bits
Name
Description
0x00
Ñ
FBP_BASE
Free buffer pool base. Holds the pointer to the Þrst entry in the free buffer pool.
FBP_BASE should be word aligned. User-deÞned.
0x04
Ñ
FBP_PTR
Free buffer pool pointer. Pointer to the current entry in the free buffer pool.
Initialize to FBP_BASE.
0x08
Ñ
FBP_ENTRY_EXT
Free buffer pool entry extension. FBP_ENTRY_EXT[0Ð3] holds the four left bits
of FBP_ENTRY. FBP_ENTRY_EXT[4Ð15] should be cleared. User-deÞned.
0x0A
0
BUSY
The CP sets this bit when it tries to fetch buffer pointer with V bit clear.
FCCE[GBPB] is also set. Initialize to zero.
1
RLI
Red-line interrupt. Set by the CP when it fetches a buffer pointer with I = 1.
FCCE[GRLI] is also set. Initialize to zero.
2Ð7
Ñ
Reserved, should be cleared.
Summary of Contents for MPC8260 PowerQUICC II
Page 1: ...MPC8260UM D 4 1999 Rev 0 MPC8260 PowerQUICC II UserÕs Manual ª ª ...
Page 66: ...lxvi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA ...
Page 88: ...1 18 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 120: ...2 32 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 138: ...Part II iv MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II Configuration and Reset ...
Page 184: ...4 46 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II ConÞguration and Reset ...
Page 202: ...Part III vi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 266: ...8 34 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 382: ...10 106 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 392: ...11 10 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 430: ...Part IV viii MOTOROLA Part IV Communications Processor Module ...
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Page 980: ...A 4 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Appendixes ...
Page 1002: ...Index 22 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA INDEX ...
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