All the get item from uvm_tlm_analysis_fifo are the last one been pushed into

[enchanter]

I try to use uvm_tlm_analysis_fifo in my scoreboard.

uvm_analysis_export #(spi_adc_item) before_export;

uvm_analysis_export #(cpu_item) after_export;

uvm_tlm_analysis_fifo #(spi_adc_item) before_fifo;

uvm_tlm_analysis_fifo #(cpu_item) after_fifo;

function void build_phase(uvm_phase phase);

before_fifo = new("before_fifo", this);

before_export = new("before_export", this);

after_fifo = new("after_fifo", this);

after_export = new("after_export", this);

endfunction // build_phase

function void connect_phase(uvm_phase phase);

before_export.connect(before_fifo.analysis_export);

after_export.connect(after_fifo.analysis_export);

endfunction : connect_phase

The before_fifo should have 8 items before the after_fifo is written one item.

If I try to use before_fifo.get every time when item is written into, I can see all the item are good.:

forever begin

before_fifo.get(before_txn);

$display("SPI_ADC_ITEM: %s", before_txn.sprint());

end

But if I wait until after_fifo is not empty, the items get from before_fifo are all the last one be written into.

forever begin

after_fifo.get(after_txn);

fifo_usage = before_fifo.used();

$display("Usage of before_fifo: %0d", fifo_usage);

for (int i = 0; i < fifo_usage; i++) begin

before_fifo.get(before_txn);

before_txn.pack_ints(num_bits);

$display("SPI_ADC_ITEM: %s", before_txn.sprint());

$display("Usage of before_fifo: %0d", before_fifo.used());

end

end

Log file:

# UVM_INFO ../../src/spi_adc_monitor.sv(39) @ 10: uvm_test_top.sample_tb0.spi_adc0 [uvm_test_top.sample_tb0.spi_adc0] Transfer collected :

# -----------------------------------------------------------------

# Name Type Size Value

# -----------------------------------------------------------------

# spi_adc_item spi_adc_item - @548

# dout sa(integral) 4 -

# [0] integral 1 'h0

# [1] integral 1 'h0

# [2] integral 1 'h1

# [3] integral 1 'h0

# len integral 32 'h4

# -----------------------------------------------------------------

#

# UVM_INFO ../../src/spi_adc_monitor.sv(39) @ 30: uvm_test_top.sample_tb0.spi_adc0 [uvm_test_top.sample_tb0.spi_adc0] Transfer collected :

# -----------------------------------------------------------------

# Name Type Size Value

# -----------------------------------------------------------------

# spi_adc_item spi_adc_item - @548

# dout sa(integral) 4 -

# [0] integral 1 'h0

# [1] integral 1 'h1

# [2] integral 1 'h1

# [3] integral 1 'h0

# len integral 32 'h4

# -----------------------------------------------------------------

#

# FIFO Usage: 2

# SPI_ADC_ITEM: 'h6000

# FIFO Usage: 1

# SPI_ADC_ITEM: 'h6000

I pack the dout to integer so '0110' show '6' at the MSB.

I have no idea what's wrong in my code. I attached my rubbish test code. Would please anyone give it look.

Thanks

Edited April 19, 2012 by enchanter
add log and attached test code.

[claudxiao]

Hi,

No server by hands, so can't run simulation based on your code, just some general feeling about your issue....

typically I suspect that the reason you can only read the last one is that, though you might continously pushed 8 items into 'before_fifo' , but the element you pushed into the fifo is always the same item...Because when you push item into buffer, you normally need to 'clone' it and then push, instead of just push the original one.. otherwise, all the 8 items share the same pointer address, hence of course share the same content when you read;(I like 'factory mode'.. you know)

And especially when you use some after_fifo use() as some trigger, that means, we can be sure, all 8 times 'push' has been done before your read attemp; but in your previous test (i.e. push->before_fifo, and get<-before_fifo), of course, even you are still only use one address, but you can read each times change before you write next one....

That's just assumption based on your description and some silly mistake of myself before, hope it can help... and all assumption is based on you forget to clone your elemetn before you push it into fifo...otherwise..just forget my words

:cool:

Edited April 27, 2012 by claudxiao