A-4 APPENDIX A: PACKET FILTER OPCODES, EXAMPLES, AND SYNTAX ERRORS

pushSPGM

Description:

Pushes the source port group mask (SPGM) onto the top of the stack. The SPGM is a bitmap representing the groups to which the source port of a packet belongs. This instruction pushes 4 bytes on to the stack.

Each port group mask is represented by a single bit in the SPGM bitmap. Port group masks are assigned to the bitmap in sequence, starting with port group mask 1 as the least significant bit through port group mask 32 as the most significant bit.

Storage Needed:

1 byte

pushDPGM

Description:

Pushes the destination port group mask (DPGM) onto the top of the stack. The DPGM is a bitmap representing the groups to which the destination port of a packet belongs. This instruction pushes 4 bytes on to the stack.

Each port group mask is represented by a single bit in the DPGM bitmap. Port group masks are assigned to the bitmap in sequence, starting with port group mask 1 as the least significant bit through port group mask 32 as the most significant bit.

Storage Needed:

1 byte

eq (equal)

Description:

Pops two values from the stack and compares them. If they are equal, a byte containing the value non-zero is pushed onto the stack; otherwise, a byte containing 0 is pushed. The size of the operands is determined by the contents of the stack.

Storage Needed:

1 byte

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3Com 2200 manual PushSPGM, Byte PushDPGM, Byte Eq equal