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| author | Josh Blum <josh@joshknows.com> | 2010-04-16 09:42:46 +0000 |
|---|---|---|
| committer | Josh Blum <josh@joshknows.com> | 2010-04-16 09:42:46 +0000 |
| commit | 835cb56ef820a69e1e6e0ccde7c5a0e78ca5ad25 (patch) | |
| tree | 4fe48bdaf92311deedfbe1a5e77dd209468a2d7d /fpga/usrp2/simple_gemac/flow_ctrl_tx.v | |
| parent | f1838b9284a124fcfb5996eaf1647a69b4473278 (diff) | |
| parent | 067491b58676cbdaa754334949a8ffc2daf32979 (diff) | |
| download | uhd-835cb56ef820a69e1e6e0ccde7c5a0e78ca5ad25.tar.gz uhd-835cb56ef820a69e1e6e0ccde7c5a0e78ca5ad25.tar.bz2 uhd-835cb56ef820a69e1e6e0ccde7c5a0e78ca5ad25.zip | |
Merge branch 'master' of git@ettus.sourcerepo.com:ettus/uhdpriv into usrp_e
Conflicts:
.gitignore
Diffstat (limited to 'fpga/usrp2/simple_gemac/flow_ctrl_tx.v')
| -rw-r--r-- | fpga/usrp2/simple_gemac/flow_ctrl_tx.v | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/fpga/usrp2/simple_gemac/flow_ctrl_tx.v b/fpga/usrp2/simple_gemac/flow_ctrl_tx.v new file mode 100644 index 000000000..f80f5a76d --- /dev/null +++ b/fpga/usrp2/simple_gemac/flow_ctrl_tx.v @@ -0,0 +1,39 @@ +
+// TX side of flow control -- when other side sends PAUSE, we wait
+
+module flow_ctrl_tx
+ (input rst,
+ input tx_clk,
+ //host processor
+ input tx_pause_en,
+ // From MAC_rx_ctrl
+ input [15:0] pause_quanta,
+ input pause_quanta_val,
+ // MAC_tx_ctrl
+ output pause_apply,
+ input paused);
+
+ // ******************************************************************************
+ // Inhibit our TX from transmitting because they sent us a PAUSE frame
+ // ******************************************************************************
+
+ // Pauses are in units of 512 bit times, or 64 bytes/clock cycles, and can be
+ // as big as 16 bits, so 22 bits are needed for the counter
+
+ reg [15+6:0] pause_quanta_counter;
+ reg pqval_d1, pqval_d2;
+
+ always @(posedge tx_clk) pqval_d1 <= pause_quanta_val;
+ always @(posedge tx_clk) pqval_d2 <= pqval_d1;
+
+ always @ (posedge tx_clk or posedge rst)
+ if (rst)
+ pause_quanta_counter <= 0;
+ else if (pqval_d1 & ~pqval_d2)
+ pause_quanta_counter <= {pause_quanta, 6'b0};
+ else if((pause_quanta_counter!=0) & paused)
+ pause_quanta_counter <= pause_quanta_counter - 1;
+
+ assign pause_apply = tx_pause_en & (pause_quanta_counter != 0);
+
+endmodule // flow_ctrl
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