codec/h264/h264dec: created tokenMap type to make things more readable

codec/h264/h264dec/cavlc.go

@@ -49,7 +49,7 @@ func init() {
 		panic(fmt.Sprintf("could not read lines from coeftokenmap.csv file, failed with error: %v", err))
 	}
 
-	coeffTokenMap, err = formCoeffTokenMap(lines)
+	coeffTokenMaps, err = formCoeffTokenMap(lines)
 	if err != nil {
 		panic(fmt.Sprintf("could not form coeff_token map, failed with err: %v", err))
 	}
@@ -202,7 +202,7 @@ func readCoeffToken(br *bits.BitReader, nC int) (trailingOnes, totalCoeff, coeff
 	val := b
 	nBits := nZeros
 	for {
-		vars, ok := coeffTokenMap[nCIdx][nZeros][int(val)]
+		vars, ok := coeffTokenMaps[nCIdx][nZeros][int(val)]
 		if ok {
 			trailingOnes = vars[0]
 			totalCoeff = vars[1]
@@ -247,31 +247,36 @@ func available(b block) bool {
 // representative of the number of defined nC ranges defined in table 9-5.
 const nColumns = 6
 
+// coeffMapping maps values of coeff_token to values of TrailingOnes(coeff_token)
+// and TotalCoeff(coeff_token) given as map[ coeff_token val ][ 0 for trailing ones
+// and 1 for totalCoef ]
+type tokenMap map[int]map[int][2]int
+
 // coeffTokenMap will a representation of table 9-5 from the specifications, and
 // is indexed as follows, coeffToken[ nC group ][ number of coeff_token leading
 // zeros ][ value of coeff_token ][ 0 for TrailingOnes(coeff_token) and 1 for
 // TotalCoef(coeff_token) ].
-var coeffTokenMap [nColumns]map[int]map[int][2]int
+var coeffTokenMaps [nColumns]tokenMap
 
 // formCoeffTokenMap populates the global [nColumns]map[int]map[int][2]int,
 // coeffTokenMap representation of table 9-5 from the specifications using lines
 // read from a corresponding CSV file coefftokenmap.csv.
-func formCoeffTokenMap(lines [][]string) ([nColumns]map[int]map[int][2]int, error) {
-	var tokenMap [nColumns]map[int]map[int][2]int
+func formCoeffTokenMap(lines [][]string) ([nColumns]tokenMap, error) {
+	var maps [nColumns]tokenMap
 
-	for i := range tokenMap {
-		tokenMap[i] = make(map[int]map[int][2]int)
+	for i := range maps {
+		maps[i] = make(tokenMap)
 	}
 
 	for _, line := range lines {
 		trailingOnes, err := strconv.Atoi(line[0])
 		if err != nil {
-			return tokenMap, fmt.Errorf("could not convert trailingOnes string to int, failed with error: %v", err)
+			return maps, fmt.Errorf("could not convert trailingOnes string to int, failed with error: %v", err)
 		}
 
 		totalCoeff, err := strconv.Atoi(line[1])
 		if err != nil {
-			return tokenMap, fmt.Errorf("could not convert totalCoeff string to int, failed with error: %v", err)
+			return maps, fmt.Errorf("could not convert totalCoeff string to int, failed with error: %v", err)
 		}
 
 		// For each column in this row, therefore each nC category, load the
@@ -298,18 +303,18 @@ func formCoeffTokenMap(lines [][]string) ([nColumns]map[int]map[int][2]int, erro
 			// This will be the value of the coeff_token (without leading zeros).
 			val, err := binToInt(v[nZeros:])
 			if err != nil {
-				return tokenMap, fmt.Errorf("could not get value of remaining binary, failed with error: %v", err)
+				return maps, fmt.Errorf("could not get value of remaining binary, failed with error: %v", err)
 			}
 
 			// Add the TrailingOnes(coeff_token) and TotalCoeff(coeff_token) values
 			// into the map for the coeff_token leading zeros and value.
-			if tokenMap[j][nZeros] == nil {
-				tokenMap[j][nZeros] = make(map[int][2]int)
+			if maps[j][nZeros] == nil {
+				maps[j][nZeros] = make(map[int][2]int)
 			}
-			tokenMap[j][nZeros][val] = [2]int{trailingOnes, totalCoeff}
+			maps[j][nZeros][val] = [2]int{trailingOnes, totalCoeff}
 		}
 	}
-	return tokenMap, nil
+	return maps, nil
 }
 
 // parseLevelPrefix parses the level_prefix variable as specified by the process