From 43653dbe1aafc9a9036735d9c2eb31f291c4bd68 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sebastien@milkymist.org>
Date: Thu, 12 Jul 2012 18:33:28 +0200
Subject: [PATCH] corelogic: reorder buffer (untested)

---
 migen/corelogic/buffers.py | 80 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 migen/corelogic/buffers.py

diff --git a/migen/corelogic/buffers.py b/migen/corelogic/buffers.py
new file mode 100644
index 000000000..b788a34fb
--- /dev/null
+++ b/migen/corelogic/buffers.py
@@ -0,0 +1,80 @@
+from migen.fhdl.structure import *
+
+class ReorderSlot:
+	def __init__(self, tag_width, data_width):
+		self.wait_data = Signal()
+		self.has_data = Signal()
+		self.tag = Signal(BV(tag_width))
+		self.data = Signal(BV(data_width))
+
+class ReorderBuffer:
+	def __init__(self, tag_width, data_width, depth):
+		self.depth = depth
+		
+		# issue
+		self.can_issue = Signal()
+		self.issue = Signal()
+		self.tag_issue = Signal(BV(tag_width))
+		
+		# call
+		self.call = Signal()
+		self.tag_call = Signal(BV(tag_width))
+		self.data_call = Signal(BV(data_width))
+		
+		# readback
+		self.can_read = Signal()
+		self.read = Signal()
+		self.data_read = Signal(BV(data_width))
+		
+		self._empty_count = Signal(BV(bits_for(self.depth)), reset=self.depth)
+		self._produce = Signal(BV(bits_for(self.depth-1)))
+		self._consume = Signal(BV(bits_for(self.depth-1)))
+		self._slots = Array(ReorderSlot(tag_width, data_width)
+			for n in range(self.depth))
+	
+	def get_fragment(self):
+		# issue
+		comb = [
+			self.can_issue.eq(self._empty_count != 0)
+		]
+		sync = [
+			If(self.issue & self.can_issue,
+				self._empty_count.eq(self._empty_count - 1),
+				If(self._produce == self.depth - 1,
+					self._produce.eq(0)
+				).Else(
+					self._produce.eq(self._produce + 1)
+				),
+				self._slots[self._produce].wait_data.eq(1),
+				self._slots[self._produce].tag.eq(self.tag_issue)
+			)
+		]
+		
+		# call
+		for n, slot in enumerate(self._slots):
+			sync.append(
+				If(self.call & slot.wait_data & (self.tag_call == slot.tag),
+					slot.wait_data.eq(0),
+					slot.has_data.eq(1),
+					slot.data.eq(self.data_call)
+				)
+			)
+		
+		# readback
+		comb += [
+			self.can_read.eq(self._slots[self._consume].has_data),
+			self.data_read.eq(self._slots[self._consume].data)
+		]
+		sync += [
+			If(self.read & self.can_read,
+				self._empty_count.eq(self._empty_count + 1),
+				If(self._consume == self.depth - 1,
+					self._consume.eq(0)
+				).Else(
+					self._consume.eq(self._consume + 1)
+				),
+				self._slots[self._consume].has_data.eq(0)
+			)
+		]
+		
+		return Fragment(comb, sync)
\ No newline at end of file