4.1.4.2 Queue N Register B (0x00000004 + 16×N)
The Queue N Register B (Figure 4-12) provides a byte count feature, which is the sum of the Queue N Register C PACKET_SIZE fields of all packets that are currently contained in the queue. This register must be read prior to reading Queue N Register D during packet pop operation if the byte count information is desired. Note, this is a saturating 32-bit counter.
Figure 4-12 Queue N Register B (0x00000004 + 16×N)
Legend: R = Read only; - n = value after reset |
Table 4-15 Queue N Register B Field Descriptions
Bit |
Field |
Description |
31-0 |
QUEUE_BYTE_COUNT |
This field indicates the sum of all PACKET_SIZE fields that are currently pushed to this queue. The sum is increased with a push and decreased with a pop. Pushes MUST include writing to Queue N Register C or this sum will remain zero. Do not read this register unless you also intend on popping the queue with Reg D. To obtain the byte count without also popping the queue, use Queue N Status and Configuration Reg B in the Queue Peek region. |