1# Copyright (c) Barefoot Networks, Inc.
2# Licensed under the Apache License, Version 2.0 (the "License")
3
4from p4_hlir.hlir import P4_AUTO_WIDTH
5from ebpfType import *
6from compilationException import *
7from programSerializer import ProgramSerializer
8
9
10class EbpfScalarType(EbpfType):
11    __doc__ = "Represents a scalar type"
12    def __init__(self, parent, widthInBits, isSigned, config):
13        super(EbpfScalarType, self).__init__(None)
14        assert isinstance(widthInBits, int)
15        assert isinstance(isSigned, bool)
16        self.width = widthInBits
17        self.isSigned = isSigned
18        self.config = config
19        if widthInBits is P4_AUTO_WIDTH:
20            raise NotSupportedException("{0} Variable-width field", parent)
21
22    def widthInBits(self):
23        return self.width
24
25    @staticmethod
26    def bytesRequired(width):
27        return (width + 7) / 8
28
29    def asString(self):
30        if self.isSigned:
31            prefix = self.config.iprefix
32        else:
33            prefix = self.config.uprefix
34
35        if self.width <= 8:
36            name = prefix + "8"
37        elif self.width <= 16:
38            name = prefix + "16"
39        elif self.width <= 32:
40            name = prefix + "32"
41        else:
42            name = "char*"
43        return name
44
45    def alignment(self):
46        if self.width <= 8:
47            return 1
48        elif self.width <= 16:
49            return 2
50        elif self.width <= 32:
51            return 4
52        else:
53            return 1  # Char array
54
55    def serialize(self, serializer):
56        assert isinstance(serializer, ProgramSerializer)
57        serializer.append(self.asString())
58
59    def declareArray(self, serializer, identifier, size):
60        raise CompilationException(
61            True, "Arrays of base type not expected in P4")
62
63    def declare(self, serializer, identifier, asPointer):
64        assert isinstance(serializer, ProgramSerializer)
65        assert isinstance(asPointer, bool)
66        assert isinstance(identifier, str)
67
68        if self.width <= 32:
69            self.serialize(serializer)
70            if asPointer:
71                serializer.append("*")
72            serializer.space()
73            serializer.append(identifier)
74        else:
75            if asPointer:
76                serializer.append("char*")
77            else:
78                serializer.appendFormat(
79                    "char {0}[{1}]", identifier,
80                    EbpfScalarType.bytesRequired(self.width))
81
82    def emitInitializer(self, serializer):
83        assert isinstance(serializer, ProgramSerializer)
84        serializer.append("0")
85