utils/conv_gen.py: use shared tables if possible

This change introduces the memory usage optimization, mentioned
in d2d9760c08f35a231d32f0ebeb73b2927e5573b3. The aim is to make
code generator able to detect, whether the same tables are used
by several convolutional code definitions, and prevent one from
writing these tables multiple times.

For now, the detection process isn't fully automatic, so all
shared polynomials should be placed inside the 'shared_polys'
dictionary, for example:

shared_polys = {
	"xcch" : [
		( G0, 1 ),
		( G1, 1 ),
	],
	"mcs" : [
		( G4, 1 ),
		( G7, 1 ),
		( G5, 1 ),
	],
}

Change-Id: I84760f5cdfdaece376b801d2e6cb2954ee875a3b

1 files changed, 61 insertions, 37 deletions

diff --git a/utils/conv_gen.py b/utils/conv_gen.py
index 62fa8adb..1ecb550a 100644
--- a/utils/conv_gen.py
+++ b/utils/conv_gen.py
@@ -164,7 +164,7 @@ class ConvolutionalCode(object):
 		# Up to 12 numbers should be placed per line
 		print_formatted(self.puncture, "%3d, ", 12, fi)
 
-	def gen_tables(self, pref, fi):
+	def print_state_and_output(self, fi):
 		pack = lambda n: \
 			sum([x << (self.rate_inv - i - 1) for i, x in enumerate(n)])
 		num_states = 1 << (self.k - 1)
@@ -186,6 +186,14 @@ class ConvolutionalCode(object):
 			self._print_term(fi, num_states, pack)
 			fi.write("};\n\n")
 
+	def gen_tables(self, pref, fi, shared_tables = None):
+		# Do not print shared tables
+		if shared_tables is None:
+			self.print_state_and_output(fi)
+			table_pref = self.name
+		else:
+			table_pref = shared_tables
+
 		if len(self.puncture):
 			fi.write("static const int %s_puncture[] = {\n" % self.name)
 			self._print_puncture(fi)
@@ -203,15 +211,15 @@ class ConvolutionalCode(object):
 		fi.write("\t.N = %d,\n" % self.rate_inv)
 		fi.write("\t.K = %d,\n" % self.k)
 		fi.write("\t.len = %d,\n" % self.block_len)
-		fi.write("\t.next_output = %s_output,\n" % self.name)
-		fi.write("\t.next_state = %s_state,\n" % self.name)
+		fi.write("\t.next_output = %s_output,\n" % table_pref)
+		fi.write("\t.next_state = %s_state,\n" % table_pref)
 
 		if self.term_type is not None:
 			fi.write("\t.term = %s,\n" % self.term_type)
 
 		if self.recursive:
-			fi.write("\t.next_term_output = %s_term_output,\n" % self.name)
-			fi.write("\t.next_term_state = %s_term_state,\n" % self.name)
+			fi.write("\t.next_term_output = %s_term_output,\n" % table_pref)
+			fi.write("\t.next_term_state = %s_term_state,\n" % table_pref)
 
 		if len(self.puncture):
 			fi.write("\t.puncture = %s_puncture,\n" % self.name)
@@ -239,6 +247,12 @@ def print_formatted(items, format, count, fi):
 
 	fi.write("\n")
 
+def print_shared(fi):
+	for (name, polys) in shared_polys.items():
+		# HACK
+		code = ConvolutionalCode(0, polys, name = name)
+		code.print_state_and_output(fi)
+
 # Polynomials according to 3GPP TS 05.03 Annex B
 G0 = poly(0, 3, 4)
 G1 = poly(0, 1, 3, 4)
@@ -249,22 +263,23 @@ G5 = poly(0, 1, 4, 6)
 G6 = poly(0, 1, 2, 3, 4, 6)
 G7 = poly(0, 1, 2, 3, 6)
 
-CCH_poly = [
-	( G0, 1 ),
-	( G1, 1 ),
-]
-
-MCS_poly = [
-	( G4, 1 ),
-	( G7, 1 ),
-	( G5, 1 ),
-]
+shared_polys = {
+	"xcch" : [
+		( G0, 1 ),
+		( G1, 1 ),
+	],
+	"mcs" : [
+		( G4, 1 ),
+		( G7, 1 ),
+		( G5, 1 ),
+	],
+}
 
 conv_codes = [
 	# xCCH definition
 	ConvolutionalCode(
 		224,
-		CCH_poly,
+		shared_polys["xcch"],
 		name = "xcch",
 		description = [
 			"xCCH convolutional code:",
@@ -277,7 +292,7 @@ conv_codes = [
 	# RACH definition
 	ConvolutionalCode(
 		14,
-		CCH_poly,
+		shared_polys["xcch"],
 		name = "rach",
 		description = ["RACH convolutional code"]
 	),
@@ -285,7 +300,7 @@ conv_codes = [
 	# SCH definition
 	ConvolutionalCode(
 		35,
-		CCH_poly,
+		shared_polys["xcch"],
 		name = "sch",
 		description = ["SCH convolutional code"]
 	),
@@ -293,7 +308,7 @@ conv_codes = [
 	# CS2 definition
 	ConvolutionalCode(
 		290,
-		CCH_poly,
+		shared_polys["xcch"],
 		puncture = [
 			 15,  19,  23,  27,  31,  35,  43,  47,  51,  55,  59,  63,  67,  71,
 			 75,  79,  83,  91,  95,  99, 103, 107, 111, 115, 119, 123, 127, 131,
@@ -317,7 +332,7 @@ conv_codes = [
 	# CS3 definition
 	ConvolutionalCode(
 		334,
-		CCH_poly,
+		shared_polys["xcch"],
 		puncture = [
 			 15,  17,  21,  23,  27,  29,  33,  35,  39,  41,  45,  47,  51,  53,
 			 57,  59,  63,  65,  69,  71,  75,  77,  81,  83,  87,  89,  93,  95,
@@ -579,7 +594,7 @@ conv_codes = [
 	# TCH_FR definition
 	ConvolutionalCode(
 		185,
-		CCH_poly,
+		shared_polys["xcch"],
 		name = "tch_fr",
 		description = ["TCH/F convolutional code"]
 	),
@@ -724,7 +739,7 @@ conv_codes = [
 	# EDGE MCS1_DL_HDR definition
 	ConvolutionalCode(
 		36,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs1_dl_hdr",
 		term_type = "CONV_TERM_TAIL_BITING",
 		description = [
@@ -739,7 +754,7 @@ conv_codes = [
 	# EDGE MCS1_UL_HDR definition
 	ConvolutionalCode(
 		39,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs1_ul_hdr",
 		term_type = "CONV_TERM_TAIL_BITING",
 		description = [
@@ -754,7 +769,7 @@ conv_codes = [
 	# EDGE MCS1 definition
 	ConvolutionalCode(
 		190,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs1",
 		description = [
 			"EDGE MCS-1 data convolutional code:",
@@ -768,7 +783,7 @@ conv_codes = [
 	# EDGE MCS2 definition
 	ConvolutionalCode(
 		238,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs2",
 		description = [
 			"EDGE MCS-2 data convolutional code:",
@@ -782,7 +797,7 @@ conv_codes = [
 	# EDGE MCS3 definition
 	ConvolutionalCode(
 		310,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs3",
 		description = [
 			"EDGE MCS-3 data convolutional code:",
@@ -796,7 +811,7 @@ conv_codes = [
 	# EDGE MCS4 definition
 	ConvolutionalCode(
 		366,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs4",
 		description = [
 			"EDGE MCS-4 data convolutional code:",
@@ -810,7 +825,7 @@ conv_codes = [
 	# EDGE MCS5_DL_HDR definition
 	ConvolutionalCode(
 		33,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs5_dl_hdr",
 		term_type = "CONV_TERM_TAIL_BITING",
 		description = [
@@ -825,7 +840,7 @@ conv_codes = [
 	# EDGE MCS5_UL_HDR definition
 	ConvolutionalCode(
 		45,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs5_ul_hdr",
 		term_type = "CONV_TERM_TAIL_BITING",
 		description = [
@@ -840,7 +855,7 @@ conv_codes = [
 	# EDGE MCS5 definition
 	ConvolutionalCode(
 		462,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs5",
 		description = [
 			"EDGE MCS-5 data convolutional code:",
@@ -854,7 +869,7 @@ conv_codes = [
 	# EDGE MCS6 definition
 	ConvolutionalCode(
 		606,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs6",
 		description = [
 			"EDGE MCS-6 data convolutional code:",
@@ -868,7 +883,7 @@ conv_codes = [
 	# EDGE MCS7_DL_HDR definition
 	ConvolutionalCode(
 		45,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs7_dl_hdr",
 		term_type = "CONV_TERM_TAIL_BITING",
 		description = [
@@ -883,7 +898,7 @@ conv_codes = [
 	# EDGE MCS7_UL_HDR definition
 	ConvolutionalCode(
 		54,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs7_ul_hdr",
 		term_type = "CONV_TERM_TAIL_BITING",
 		description = [
@@ -898,7 +913,7 @@ conv_codes = [
 	# EDGE MCS7 definition
 	ConvolutionalCode(
 		462,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs7",
 		description = [
 			"EDGE MCS-7 data convolutional code:",
@@ -912,7 +927,7 @@ conv_codes = [
 	# EDGE MCS8 definition
 	ConvolutionalCode(
 		558,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs8",
 		description = [
 			"EDGE MCS-8 data convolutional code:",
@@ -926,7 +941,7 @@ conv_codes = [
 	# EDGE MCS9 definition
 	ConvolutionalCode(
 		606,
-		MCS_poly,
+		shared_polys["mcs"],
 		name = "mcs9",
 		description = [
 			"EDGE MCS-9 data convolutional code:",
@@ -949,10 +964,19 @@ if __name__ == '__main__':
 	f.write(mod_license + "\n")
 	f.write("#include <stdint.h>\n")
 	f.write("#include <osmocom/core/conv.h>\n\n")
+	print_shared(f)
 
 	# Generate the tables one by one
 	for code in conv_codes:
 		sys.stderr.write("Generate '%s' definition\n" % code.name)
-		code.gen_tables(prefix, f)
+
+		# Check whether shared polynomials are used
+		shared = None
+		for (name, polys) in shared_polys.items():
+			if code.polys == polys:
+				shared = name
+				break
+
+		code.gen_tables(prefix, f, shared_tables = shared)
 
 	sys.stderr.write("Generation complete.\n")