PXF4336 Datasheet, PDF (139/425 Pages) Infineon Technologies AG – ABM Premium ATM Buf fer Manager

ABM-P
PXF 4336 V1.1
Operational Description
First, a dimensionless floating point number T_SB is calculated from CCR_SB as follows:
T_SB
=
-----^S----^Y----^S-----^C----^L----^K-------
32 × CCR_SB
(6)
with T_SB constrained internally to
T_SB
≤
2 ¹⁴
–
--¹---
2⁸
(7)
Therefore T_SBmax = 16383,99609.
Given a particular T_SB, the internal parameters for the SB rate can be calculated:
The integer division factor is calculated as:
T_SB(i) = T_SB
(8)
The fractional division factor is calculated as:
T_SB(f) = min( áT_SB – T_SB ñ × 2⁸ , 255 )
(9)
with X designating the integer part of X and X designating the next integer
greater or equal to X.
The integer and fractional division factor defined above are referred to as IntRate and
FracRate in the register description. Refer to “USCTI/DSCTI” on Page 309 and
“USCTFT/DSCTFT” on Page 318.
The minimum cell rate possible in an SB is configured with T_SBmax according to:
MCR_SB
=
----^S-----^Y----^S-----^C----^L----^K------
32 × T_SBmax
(10)
The following Table 4-2 shows the rate limits for the SB as a function of the system clock
SYSCLK.
Table 4-2 Scheduler Block Rate Limits
SYSCLK
[MHz]
51.84
60
Cell cycle
[ns]
617
533
PCR_SB
[cells/s]
1556000
1811000
MCR_SB
[cells/s]
MBR_SB
[bit/s] (53)
98.8769 41924
114.4409 48523
In Table 4-3, the numerical values of the integer and fractional divisors are shown for
different desired CCR_SB. Due to the limited resolution of the internal rate representation,
Data Sheet
139
2001-12-17