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Literals
CoreDSL 2 supports C-style literals in binary (prefix 0b), octal (prefix 0), decimal and hexadecimal (prefix 0x) representations.
These literals have the unsigned type with the minimal width required to represent the value.
The u, l and ll suffixes are ignored.
As bool is an alias for unsigned<1>, we define bool false = 0, true = 1;.
The automatic width-inference may be inconvenient in certain situations.
To that end, CoreDSL 2 also supports integer literals with an explicit width specification in a Verilog-inspired syntax, i.e. <size>'<signed><base><value>.
The base may be b (binary), o (octal), d (decimal) or h (hexadecimal).
The literal <value> must be representable in the specified <size> bits.
| Expression | Type | Value (decimal) |
|---|---|---|
0 |
unsigned<1> |
0 |
1 |
unsigned<1> |
1 |
-1 |
signed<2> |
-1 |
3 |
unsigned<2> |
3 |
-3 |
signed<3> |
-3 |
0b101010 |
unsigned<6> |
42 |
(signed) 0b101010 |
signed<6> |
-22 |
052 |
unsigned<6> |
42 |
0x2A |
unsigned<6> |
42 |
11'd42 |
unsigned<11> |
42 |
4'sb1011 |
signed<4> |
-5 |
6'sd42 |
signed<6> |
-22 |
16'hFFFF |
unsigned<16> |
2^16 - 1 |
5'd42 |
Error! |
NB 1: We do not exploit the asymmetry of the two's complement representation here.
Technically, -1 could be represented as a signed<1> type (i.e., just the sign bit), but as it is parsed as UnaryMinus(IntLiteral(1)), the type rules mandate that -1 has the static type signed<2>.
NB 2: Similarly, we decided against representing 0 with the unsigned<0> type. The expected gains are small, and zero-bit types always require special handling somewhere in the compilation pipeline (e.g. LLVM/MLIR do not support them) -- hence, avoiding them at the language level ensures consistency across CoreDSL implementations.
CoreDSL 2 supports C-like character ('c') and string ("string") literals.
Wide characters and unicode strings (L and U prefixes) are not supported.
If an implementation supports escape sequences such as '\n', \042, etc., these shall carry the same meaning as in C.
C-like compound literals such as (struct foo){1, 2} and (union bar){.baz = 33} are supported.