Intel IXP1200 4.6.5 msgq_receive(), 4.6.6 Example

IXP1200 Network Processor Family ATM OC-3/12/Ethernet IP Router Example Design

44 Application Note

Modified on: 3/20/02,

msgq_send(io_message, MSGQ_HANDLE, RAM_OPTION)

4.6.5 msgq_receive()

Receives a message from the queue.

msgq_receive(io_xfer, MSGQ_HANDLE)

4.6.6 Example

In the following example, a single microengine uses four threads to receive from INPUT_MSGQ,

perform some processing, then send to OUTPUT_MSGQ in the order received. The example shows

how critical sections are used to control multiple threads accessing the same queue, and how

sequence numbers can be used to maintain queue order.

Parameter Description

io_message The message to be sent. Valid messages must have bit 31 clear, and must not

be 0. 0 is returned on success, the message is untouched on failure.

MSGQ_HANDLE Parameters described in “MSGQ_HANDLE Parameters”.

RAM_OPTION ctx_swap, sig_done, no_option -- depending on the behavior desired for the

write at the end of msgq_send().

Parameter Description

io_xfer A read/write SRAM transfer register for use by msgq_receive(). The write

transfer is terminated and the read transfer returns the message.

MSGQ_HANDLE Parameters described in “MSGQ_HANDLE Parameters”.

#define INPUT_MSGQ @msgq_in_index, @msgq_in_base, MSGQ_IN_BASE_ADDR, MSGQ_SYNC,

scratch, LWCOUNT16

#define OUTPUT_MSGQ @msgq_out_index, @msgq_out_base, MSGQ_OUT_BASE_ADDR,

MSGQ_SYNC, scratch, LWCOUNT16

#define MY_SEQUENCE_HANDLE my_seq_number, @enter, @one, @exit, @one, 32

msgq_init_queue(INPUT_MSGQ) ; must complete before any threads access queue

msgq_init_queue(OUTPUT_MSGQ) ; must complete before any threads access queue

...

msgq_init_regs(INPUT_MSGQ)

msgq_init_regs(OUTPUT_MSGQ)

sequence_init(MY_SEQUENCE)

critsect_init(@mutex)

...

critsect_enter(@mutex) ; allow only 1 thread to access queue at a time

sequence_enter(MY_SEQUENCE) ; remember the order messages were received

msgq_receive($xfer, INPUT_MSGQ) ; receive a message

critsect_exit(@mutex) ; allow next thread to receive

Contents

Main Application Note Contents Page Page Figures 1.0 Introduction 1.1 Purpose of ATM Example Design 1.2 Scope of Example Design 1.2.1 Supported / Not Implemented Functions 1.3 Background 1.3.1 Ethernet, IP and AAL5 Protocol Processing 1.3.2 Frame and PDU Length vs. IP Packet Length 1.3.3 Expected Ethernet Transmit Bandwidth 1.4 Execution Environment 1.4.1 Software Page 1.4.2 Hardware 2.0 System Overview 2.1 System Programming Model 2.2 StrongARM Core Software 2.3 Software Partitioning Modified on: 3/20/02, 2.3.1 Lookup Tables Not shown in the diagrams, the microengines make use of either three or four lookup tables: Route microengine and the Ethernet Receive microengine. verification. * Modified on: 3/20/02, 2.4.1.2 IP Lookup Table Modified on: 3/20/02, 2.4.2 Ethernet to ATM D at a Flo w 2.5 StrongARM Core Initialization 2.6 Microengine Initialization 3.0 Microengine Functional Blocks 3.1 ATM Receive Microengine 3.1.1 Structure Application Note 21 Modified on: 3/20/02, 3.1.2 High Level Algorithm Figure 12. ATM Receive High Level Algorithm if(ATM header hits in VC cach 3.2 ATM Transmit Microengine 3.2.1 High Level Algorithm 3.3 IP-Router Microengine 3.3.1 Structure 3.3.2 High Level Algorithm 3.4 Ethernet Receive Microengine 3.5 Ethernet Transmit Microengine 3.5.1 Ethernet Transmit Structure 3.5.2 High Level Algorithm 3.6 CRC-32 Calculations using IXP1240/1250 Hardware 3.6.1 CRC-32 Hardware Checking on Receive Page 3.6.2 CRC-32 Hardware Generation on Transmit 3.6.2.1 Transmit Alignment 3.7 CRC-32 Checker and Generator Microengines (Soft-CRC) 3.7.2 CRC -32 Checker and Generator High Level Algorithm 3.7.3 CRC-32 Computation 4.0 Software Subsystems & Data Structures 4.1 Virtual Circuit Lookup Table - atm_vc_table.uc 4.1.1 VC Table Function Page 4.1.3 VC_TABLE_LINEAR Structure . . . 4.1.4 VC Table Management API - atm_utils.c 4.1.5 VC Table Entry Modified on: 3/20/02, Figure 24. VC Lookup Table Entry (VC_TABLE_LINEAR) 4.2 Virtual Circuit Lookup Table Cache 4.2.1 VC Cache Function 4.2.1.1 OC-12 Configuration 4.2.1.2 OC-3 Configuration 4.2.2 VC Cache Structure 4.2.3 VC Cache API 4.3 IP Lookup Table 4.3.1 IP Table Function 4.3.2 IP Table Structure 4.3.3 IP Table Management API 4.3.3.1 route_table_init() 4.3.3.2 mtu_change() 4.3.3.3 atm_route_add() 4.3.3.4 enet_route_add() 4.3.3.5 rt_ent_info() 4.3.3.6 route_delete() 4.3.3.7 rt_help () 4.3.4 IP Route Table Entry 4.4 SRAM Buffer Descriptors and DRAM Data Buffers Figure 25. IP Route Table Entry - ATM Destination Figure 26. IP Route Table Entry - Ethernet Destination Modified on: 3/20/02, SRAM 4.4.1 SRAM Buffer Descriptor Format Figure 27. SRAM Descriptor to DRAM Buffer Mapping SRAM Figure 28. Buffer Descriptor Format for ATM Transmit Destination Port Modified on: 3/20/02, 4.4.2 DRAM Data Buffer Format Figure 29. Buffer Descriptor Format for Ethernet Transmit Destination Port Figure 30. DRAM Data Buffer Format - 12 Byte Offset (Received by ATM) Figure 31. DRAM Data Buffer Format - 6 Byte Offset (Received by ATM, Transmitted by Ethernet) Figure 32. DRAM Data Buffer Format - 6 Byte Offset (Received by Ethernet, Transmitted by ATM) 4.5 Sequence Numbers - sequence.uc 4.5.1 SEQUENCE_HANDLE Usage 4.5.2 Usage Model 4.5.2.1 Example 4.6 Message Queues - msgq.uc 4.6.1 MSGQ_HANDLE Parameters 4.6.2 msgq_init_queue() 4.6.3 msgq_init_regs() 4.6.4 msgq_send() Modified on: 3/20/02, 4.6.5 msgq_receive() Receives a message from the queue. 4.6.6 Example 4.7 Buffer Descriptor Queues - bdq.uc 4.7.1 BDQ Manag ement Macros 4.7.1.1 Features 4.7.1.2 Limitations 4.8 Counters Page 4.8.2.3 Global Counter Enable and Flags Global Counter Enable and Flags Counter Flags Modified on: 3/20/02, 4.8.3 counters.uc 4.8.3.1 counter_reset() Resets the specified counter to zero. 4.8.3.2 counter_inc() Increments the specified counter. 4.8.3.3 port_counter_inc() port_counter_inc() Algorithm Example Modified on: 3/20/02, 4.8.4 counters.c 4.8.4.1 counters_init() Initializes all counters. 4.8.4.2 counters_print() Prints the names and values of all counters. Example 4.9 Global $transfer Register Name Manager - xfer.uc 4.10 Mutex Vectors 4.10.1 mutex_vector_init() 4.10.2 mutex_vector_enter() 4.10.3 mutex_vector_exit() 4.11 Inter-Thread Signalling 5.0 Project Configuration / Modifying the Example Design 5.1 project_config.h 5.2 system_config.h 5.3 Switching Between Hardware Configurations 6.0 Testing Environments 7.0 Simulation Support (Scripts, etc.) 8.0 Limitations 9.0 Extending the Example Design Modified on: 3/20/02, 10.0 Document Conventions 11.0 Acronyms & Definitions Figure 37. Illustration of Array of 32-bit Words Figure 38. Illustration of Byte Sequence Figure 39. Definitions 12.0 Related Documents Modified on: 3/20/02, Figure 39. Definitions (Continued)