add myhdl mux.py experiment

diff --git a/src/myhdl/mux.py b/src/myhdl/mux.py
new file mode 100644 (file)
index 0000000..6eeba5c
--- /dev/null
+++ b/src/myhdl/mux.py
@@ -0,0 +1,132 @@
+# mux.py
+
+from math import log
+from myhdl import *
+
+period = 20  # clk frequency = 50 MHz
+
+
+@block
+def mux4(clk, in_a, in_b, in_c, in_d,
+         selector, out):
+    sel_r = Signal(intbv(0)[2:0])
+    sel25 = Signal(intbv(0)[4:0])
+
+    #@always(clk.posedge, reset_n.negedge)
+    #def logic_reg():
+    #    if reset_n == 0:
+    #        out.next = 0
+    #    else:
+    #        out.next = count_next
+
+    @always(clk.posedge)
+    def logic_selection():
+        sel_r.next = selector
+
+    @always(clk.posedge)
+    def logic_next():
+        if selector != sel_r:
+            sel25.next = intbv(0)[2:0]
+        else:
+            if selector == intbv(0)[2:0]:
+                sel25.next = intbv(1)[4:0]
+            if selector == intbv(1)[2:0]:
+                sel25.next = intbv(2)[4:0]
+            if selector == intbv(2)[2:0]:
+                sel25.next = intbv(4)[4:0]
+            if selector == intbv(3)[2:0]:
+                sel25.next = intbv(8)[4:0]
+
+    #@always(clk.posedge, clk.negedge)
+    @always(sel25, in_a, in_b, in_c, in_d)
+    def make_out():
+        out.next = bool(in_a if sel25[0] else False) | \
+                   bool(in_b if sel25[1] else False) | \
+                   bool(in_c if sel25[2] else False) | \
+                   bool(in_d if sel25[3] else False)
+
+    return instances()  # return all instances
+
+
+# testbench
+@block
+def mux_tb():
+
+    clk = Signal(bool(0))
+    in_a = Signal(intbv(0)[1:0])
+    in_b = Signal(intbv(0)[1:0])
+    in_c = Signal(intbv(0)[1:0])
+    in_d = Signal(intbv(0)[1:0])
+    selector = Signal(intbv(0)[2:0])
+    out = Signal(bool(0))
+
+    mux_inst = mux4(clk, in_a, in_b, in_c, in_d, selector, out)
+
+    @instance
+    def clk_signal():
+        while True:
+            clk.next = not clk
+            if clk:
+                in_a.next = not in_a
+                if in_a:
+                    in_b.next = not in_b
+                    if in_b:
+                        in_c.next = not in_c
+                        if in_c:
+                            in_d.next = not in_d
+                            if in_d:
+                                if selector == 0:
+                                    selector.next = 3
+                                else:
+                                    selector.next = selector - 1
+            yield delay(period // 2)
+
+    # print simulation data on screen and file
+    file_data = open("mux.csv", 'w')  # file for saving data
+    # # print header on screen
+    s = "{0},{1},{2},{3},{4},{5}".format("in_a", "in_b", "in_c", "in_d",
+                                         "selector", "out")
+    print(s)
+    # # print header to file
+    file_data.write(s)
+    # print data on each clock
+
+    @always(clk.posedge)
+    def print_data():
+        # print on screen
+        # print.format is not supported in MyHDL 1.0
+        s = str(in_a) + "," + str(in_b) + "," + str(in_c) + "," + str(in_d)
+        s = s + "," + str(selector) + "," + str(out)
+        print(s)
+
+        # print in file
+        # print.format is not supported in MyHDL 1.0
+        #file_data.write(s + "\n")
+
+    return instances()
+
+
+def main():
+
+    clk = Signal(bool(0))
+    in_a = Signal(intbv(0)[1:0])
+    in_b = Signal(intbv(0)[1:0])
+    in_c = Signal(intbv(0)[1:0])
+    in_d = Signal(intbv(0)[1:0])
+    selector = Signal(intbv(0)[2:0])
+    out = Signal(bool(0))
+
+    mux_v = mux4(clk, in_a, in_b, in_c, in_d, selector, out)
+    mux_v.convert(hdl="Verilog", initial_values=True)
+
+    # test bench
+    tb = mux_tb()
+    tb.convert(hdl="Verilog", initial_values=True)
+    # keep following lines below the 'tb.convert' line
+    # otherwise error will be reported
+    tb.config_sim(trace=True)
+    tb.run_sim(66 * period)  # run for 15 clock cycle
+
+
+if __name__ == '__main__':
+    main()