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Regarding Strobe IN AXI4

"The WSTRB[n:0] signals when HIGH, specify the byte lanes of the data bus that contain valid information. There
is one write strobe for each eight bits of the write data bus, therefore WSTRB[n] corresponds to
WDATA[(8n)+7: (8n)].
A master must ensure that the write strobes are HIGH only for byte lanes that contain valid data."   -- -->
THIS WHAT GIVEN IN AXI4 PROTOCOL SPECIFICATIONS

Like I am having a confusion here what exactly it indicates like i am presenting the possible use cases and could someone tell me whether my assumptions are correct!!

I am taking WDATA BUS width as 128 bits wide and WSTRB corresponds to 16 bits 

USE CASE- I

MASTER                                                  SLAVE

ADDR:0
Transfer Size: 16 bits                                     Slave will receive data as 2 like strb 1 indicate like [7:0] are valid bytes
Transfer Length: Single beat
Data to be written is 2
Burst type: Fixed
Strobe  here is 1 


USE CASE- II

MASTER                                                  SLAVE

ADDR:0
Transfer Size: 16 bits                          In this case strobe is 2 therefore [15:8]  is a valid byte and slave would read the value as 0 or the master will tend to shift the data "2" in [15:8] and the slave would read that shifted data
Transfer Length: Single beat
Data to be written is 2
Burst type: Fixed
Strobe  here is 2

USE CASE- III

MASTER                                                  SLAVE

ADDR:0
Transfer Size: 16 bits                                   like strb 3 indicate like [7:0] and [15:8] are valid bytes and so slave would read data as 02
Transfer Length: Single beat
Data to be written is 2
Burst type: Fixed
Strobe  here is 3

 
Could someone tell me out of these three test cases which test case is correct and if possible could you give me a solution for it....As Wstrobe indicates these are the valid bytes in the particular data bus and whether master should often obey the strobe signal and based on that it should write the data into the slave memory locations..

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