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5.27 Receive Channel 0-7 Free Buffer Count Register (RX nFREEBUFFER)
Ethernet Media Access Controller (EMAC) Registers
The receive channel 0-7 free buffer count register (RX nFREEBUFFER) is shown in Figure 53 and
described in Table 52 .
Figure 53. Receive Channel n Free Buffer Count Register (RX nFREEBUFFER)
31 16
Reserved
R-0
15 0
RX nFREEBUF
WI-0
LEGEND: R = Read only; WI = Write to increment; - n = value after reset
Table 52. Receive Channel n Free Buffer Count Register (RX nFREEBUFFER) Field Descriptions
Bit Field Value Description
31-16 Reserved 0 Reserved
15-0 RX nFREEBUF 0-FFh Receive free buffer count. These bits contain the count of free buffers available. The
RXFILTERTHRESH value is compared with this field to determine if low priority frames should be
filtered. The RX nFLOWTHRESH value is compared with this field to determine if receive flow
control should be issued against incoming packets (if enabled). This is a write-to-increment field.
This field rolls over to 0 on overflow.
If hardware flow control or QOS is used, the host must initialize this field to the number of available
buffers (one register per channel). The EMAC decrements the associated channel register for each
received frame by the number of buffers in the received frame. The host must write this field with
the number of buffers that have been freed due to host processing.
SPRU941A – April 2007 Ethernet Media Access Controller (EMAC)/ 93
Management Data Input/Output (MDIO)
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