From 45e5589ed9c555c604fb66be9f314c02ff5fb9e4 Mon Sep 17 00:00:00 2001
From: Matt Ettus <matt@ettus.com>
Date: Thu, 10 Jun 2010 11:34:18 -0700
Subject: first attempt at cleaning up the build system

---
 usrp2/fifo/fifo_spec.txt | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 usrp2/fifo/fifo_spec.txt

(limited to 'usrp2/fifo/fifo_spec.txt')

diff --git a/usrp2/fifo/fifo_spec.txt b/usrp2/fifo/fifo_spec.txt
new file mode 100644
index 000000000..133b9fa8e
--- /dev/null
+++ b/usrp2/fifo/fifo_spec.txt
@@ -0,0 +1,36 @@
+
+
+FIFO and Buffer Interface Spec
+
+Buffer Interface Data Wires -- matches fifo36
+     DATA[31:0]
+     FLAGS[3:0]
+     Bit 0	SOP
+     Bit 1	EOP
+	If SOP=1 && EOP=1, OCC contains error flags
+     Bits 3:2	OCC[1:0] --> 00 = all 4 bytes
+		     01 = 1 byte
+		     10 = 2 bytes
+		     11 = 3 bytes
+
+fifo36 -->  {OCC[1:0],EOP,SOP,DATA[31:0]}
+       OCC same as buffer interface
+
+fifo19 -->  {OCC,EOP,SOP,DATA[15:0]}    
+       Doesn't fit well into BRAM, dist RAM ok
+       OCC = 1 means last word is half full
+	   = 0 means last word is full
+
+fifo18 -->  {EOP,SOP,DATA[15:0]}
+       No half-word capability?  Should we drop sop instead?
+
+Control Wires - Data into FIFO
+	SRC_RDY_i    Upstream has data for me
+	DST_RDY_o    I have space
+		     Transfer occurs if SRC_RDI_i && DST_RDY_o
+	
+Control Wires - Data out of FIFO
+	SRC_RDY_o    I have data for downstream
+	DST_RDY_i    Downstream has space
+		     Transfer occurs if SRC_RDI_o && DST_RDY_i
+	
-- 
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