ice40: Importer for placed ice40 designs from arachne

Signed-off-by: David Shah <davey1576@gmail.com>

ice40/.gitignore

@@ -3,3 +3,5 @@
 /blinky_tb.vcd
 /picorv32.v
 /chipdbs/
+*.blif
+

ice40/picorv32_arachne.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+set -ex
+rm -f picorv32.v
+wget https://raw.githubusercontent.com/cliffordwolf/picorv32/master/picorv32.v
+yosys -p 'synth_ice40 -nocarry -blif picorv32.blif -top top' picorv32.v picorv32_top.v
+arachne-pnr -d 8k --post-place-blif picorv32_place.blif picorv32.blif
+yosys picorv32_place.blif -o picorv32_place.json
+./transform_arachne_loc.py picorv32_place.json > picorv32_place_nx.json
+../nextpnr-ice40 --hx8k --asc picorv32.asc --json picorv32_place_nx.json

ice40/transform_arachne_loc.py

@@ -0,0 +1,24 @@
+#!/usr/bin/env python3
+import json
+import sys
+import re
+
+with open(sys.argv[1]) as f:
+    data = json.load(f)
+    
+for mod, moddata in data["modules"].items():
+    if "cells" in moddata:
+        for cell, celldata in moddata["cells"].items():
+            pos = re.split('[,/]', celldata["attributes"]["loc"])
+            pos = [int(_) for _ in pos]
+            if celldata["type"] == "ICESTORM_LC":
+                celldata["attributes"]["BEL"] = "X%d/Y%d/lc%d" % (pos[0], pos[1], pos[2])
+            elif celldata["type"] == "SB_IO":
+                celldata["attributes"]["BEL"] = "X%d/Y%d/io%d" % (pos[0], pos[1], pos[2])
+            elif "RAM" in celldata["type"]:
+                celldata["attributes"]["BEL"] = "X%d/Y%d/ram" % (pos[0], pos[1])
+            elif celldata["type"] == "SB_GB":
+                celldata["attributes"]["BEL"] = "X%d/Y%d/gb" % (pos[0], pos[1])
+            else:
+                assert False
+print(json.dumps(data, sort_keys=True, indent=4))