c2go – Convert C to Go

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This is a subproject of the Go+ project. Its goal is converting any C project into Go without any human intervention and keeping performance close to C.

  • Make it passed. Stage: Done Almost. We have compiled libc (in progress) and sqlite3 (done).
  • Make it correct. Stage: Doing. We ported libc-test to test c2go and libc. Coverage: Coverage Status
  • Make it fast. Stage: Planning.

Screen Shot1

How to run examples?

Run an example:

  • Build c2go tools: go install -v ./...
  • Go testdata/xxx directory, and run c2go .

Run/Test multiple examples:

  • Run examples: c2go ./...
  • Test examples: c2go -test ./...

How c2go is used in Go+

Here is an example to show how Go+ interacts with C.

import "C"

C.printf C"Hello, c2go!\n"
C.fprintf C.stderr, C"Hi, %7.1f\n", 3.14

Here we use import "C" to import libc. It’s an abbreviation for import "C/github.com/goplus/libc". It is equivalent to the following code:

import "C/github.com/goplus/libc"

C.printf C"Hello, c2go!\n"
C.fprintf C.stderr, C"Hi, %7.1f\n", 3.14

In this example we call two C standard functions printf and fprintf, passing a C variable stderr and two C strings in the form of C"xxx" (a Go+ syntax to represent C style strings).

Run gop run . to see the output of this example:

Hello, c2go!
Hi,     3.1

What’s our plan?

  • First, support most of the syntax of C. Stage: Done Almost, see supported C syntax.
  • Second, compile sqlite3 to fix c2go bugs and get list of its dependent C standard libary fuctions. Stage: Done, see github.com/goplus/sqlite and its dependent fuctions.
  • Third, support most of C standard library functions (especially that used by sqlite3), and can import them by Go+. Stage: Doing, see detailed progress here.
  • Last, support all custom libraries, especially those well-known open source libraries. Stage: Planning.

Tested Platform

  • MacOS: 1.17.x
  • Linux: ubuntu-20.04 (temporarily skip testdata/qsort)
  • Windows

Supported C syntax

Data structures

  • Void: void
  • Boolean: _Bool, bool
  • Integer: [signed/unsigned] [short/long/long long] int
  • Enum: enum
  • Float: float, double, long double
  • Character: [signed/unsigned] char
  • Wide Character: wchar_t
  • Large Integer: [signed/unsigned] __int128
  • Complex: _Complex float/double/long double
  • Typedef: typedef
  • Pointer: *T, T[]
  • Array: T[N], T[]
  • Array Pointer: T(*)[N]
  • Function Pointer: T (*)(T1, T2, …)
  • Struct: struct
  • Union: union
  • BitField: intType :N

Operators

  • Arithmetic: a+b, a-b, a*b, a/b, a%b, -a, +a
  • Increment/Decrement: a++, a–, ++a, –a
  • Comparison: a<b, a<=b, a>b, a>=b, a==b, a!=b
  • Logical: a&&b, a||b, !a
  • Bitwise: a|b, a&b, a^b, ~a, a<<n, a>>n
  • Pointer Arithmetic: p+n, p-n, p-q, p++, p–
  • Assignment: =
  • Operator Assignment: a<op>=b
  • BitField Assignment: =
  • BitField Operator Assignment: a<op>=b
  • Struct/Union/BitField Member: a.b
  • Array Member: a[n]
  • Pointer Member: &a, *p, p[n], n[p], p->b
  • Comma: a,b
  • Ternary Conditional: cond?a:b
  • Function Call: f(a1, a2, …)
  • Conversion: (T)a
  • Sizeof: sizeof(T), sizeof(a)
  • Offsetof: __builtin_offsetof(T, member)

Literals

  • Boolean, Integer
  • Float, Complex Imaginary
  • Character, String
  • Array: (T[]){ expr1, expr2, ... }
  • Array Pointer: &(T[]){ expr1, expr2, ... }
  • Struct: struct T{ expr1, expr2, ... }

Initialization

  • Basic: T a = expr
  • Array: T a[] = { expr1, expr2, ... }, T a[N] = { expr1, expr2, ... }
  • Struct: struct T a = { expr1, expr2, ... }, struct T a = { .a = expr1, .b = expr2, ... }
  • Union: union T a = { expr }, union T a = { .a = expr }
  • Array in Struct: struct { T a[N]; ... } v = { { expr1, expr2, ... }, ... }, struct { T a[N]; ... } v = { { [0].a = expr1, [1].a = expr2, ... }, ... }

Control structures

  • If: if (cond) stmt1 [else stmt2]
  • Switch: switch (tag) { case expr1: stmt1 case expr2: stmt2 default: stmtN }
  • For: for (init; cond; post) stmt
  • While: while (cond) stmt
  • Do While: do stmt while (cond)
  • Break/Continue: break, continue
  • Goto: goto label

Functions

  • Parameters
  • Variadic Parameters
  • Variadic Parameter Access
  • Return

GitHub

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