feat: publish FreeRTOS C FC07 card

vendor/Hazard3/hdl/arith/muldiv_model.py

@@ -0,0 +1,65 @@
+#!/usr/bin/env python3
+
+# Quick reference model for sequential unsigned multiply/divide/modulo
+
+def div_step(w, accum, divisor):
+	sub_tmp = accum - (divisor << (w - 1))
+	underflow = sub_tmp < 0
+	if not underflow:
+		accum = sub_tmp
+	accum = (accum << 1) | (not underflow)
+	return accum
+
+def divmod(w, dividend, divisor, debug=True):
+	accum = dividend
+	for i in range(w):
+		accum_prev = accum
+		accum = div_step(w, accum, divisor)
+		if debug:
+			print("Step {:02d}: accum {:0{}x} -> {:0{}x}".format(
+				i, accum_prev, int(w / 2), accum, int(w / 2)))
+	return (accum >> w, accum & ((1 << w) - 1))
+
+def mul_step(w, accum, multiplicand):
+	add_en = accum & 1
+	accum = accum >> 1
+	if add_en:
+		accum += (multiplicand << (w - 1))
+	return accum
+
+def mul(w, multiplicand, multiplier, debug=True):
+	accum = multiplier
+	for i in range(w):
+		accum_prev = accum
+		accum = mul_step(w, accum, multiplicand)
+		if debug:
+			print("Step {:02d}: accum {:0{}x} -> {:0{}x}".format(
+				i, accum_prev, int(w / 2), accum, int(w / 2)))
+	return (accum >> w, accum & ((1 << w) - 1))
+
+def divtest(w=4):
+	for i in range(2 ** w):
+		for j in range(1, 2 ** w):
+			gatemod, gatediv = divmod(w, i, j, debug=False)
+			goldmod, golddiv = (i % j, i // j)
+			print("{:02d} % {:02d} = {:02d} (gold {:02d}); ./. = {:02d} (gold {:02d})"
+				.format(i, j, gatemod, goldmod, gatediv, golddiv))
+			assert(gatemod == goldmod)
+			assert(gatediv == golddiv)
+
+def multest(w=4):
+	for i in range(2 ** w):
+		for j in range(2 ** w):
+			gateh, gatel = mul(w, i, j, debug=False)
+			gold = i * j
+			goldl, goldh = (gold & ((1 << w) - 1), gold >> w)
+			print("{:02d} * {:02d} = ({:02d} (gold {:02d}), {:02d} (gold {:02d})"
+				.format(i, j, gateh, goldh, gatel, goldl))
+			assert(gatel == goldl)
+			assert(gateh == goldh)
+
+if __name__ == "__main__":
+	print("Test division:")
+	divtest()
+	print("Test multiplication:")
+	multest()