Topics

1

Ideas / Struct wrapping (multi-dimensional) arrays

« on: December 18, 2020, 05:18:35 PM »

Gnu C extension allows:
void * foo (int n) {
struct S { int data[n]; };
int (*s)[n] = malloc( sizeof (int[n]) );
...
}
which is very convenient. It would be even better to allow support for the following:
struct S {
int n;
f32 (*data)[.n]; // the ".n" refers to the internal field
}

It would be even more awesome to allow wrapping multi-dimensional arrays:
struct S2 {
int m;
int n;
f32 (*d)[.m][.n];
}
struct S2 a2;
a2.m = 100;
a2.n = 50;
a2.d = malloc( sizeof( f32[a2.m][a2.n] );
(*a2.d)[0][0] = (*a2.d)[1][1] + (*a2.d)[2][3];

If we then combine with my previous suggestion of allowing array access syntax on "fat pointers" we could do:
(*a2)[0][0] = (*a2)[1][1] + (*a2)[2][3];

2

Ideas / Fat pointer syntax support for 1D array like structs

« on: December 18, 2020, 04:39:20 PM »

It would be nice to allow the following type of syntax:
struct S {
int len;
f32 data[];
};

struct S *s = malloc( sizeof( struct S ) + 100 * sizeof( f32 ) );
s->len = 100;
(*s)[0] = (*s)[1] + (*s)[2];

So if a struct ends with a variable length array (or just a pointer type) then the array access syntax using [] is honored.

3

General Discussion / C function and type macros

« on: June 05, 2018, 07:59:24 PM »

I am trying to interface the C library lapacke to C2, however some of the functions and types in lapacke are defined to be macros. For example lapack_make_complex_float is a macro that takes 2 float arguments and returns a "complex" number whose type is the macro lapack_complex_float. Is there a way to handle these issues in the .c2i files? If the lapacke.h file could be #include'd in the generated C files this would be a solvable problem I think.

Otherwise I have to figure out the precise expansions of these macros on my platform and only write .c2i files for that.
Thanks.
--shiv--

4

General Discussion / VLA crash

« on: March 08, 2017, 04:59:55 AM »

The following code:

module test;
import stdio;
public func int32 main () {
   const uint64[2] Dims = {2, 3}
   float32[Dims[0]][Dims[1]] p;
   p[0][0] = 1;
   p[0][1] = 2;
   stdio.printf ("%g %g", p[0][0], p[0][1]);
  return 0;
}

causes the following error:
c2c: /home/shiv/c2compiler/c2c/CGenerator/CCodeGenerator.cpp:485: void C2::CCodeGenerator::EmitDecl(const C2::Decl *, C2::StringBuilder &): Assertion `D' failed.
Aborted (core dumped)

Not sure what Assert 'D' is?
Thanks.
--shiv--

5

General Discussion / Complex numbers

« on: March 06, 2017, 05:41:57 AM »

What would it take to support complex numbers in c2? I'm assuming c2 does not automatically overload the arithmetic operators so wrappers will have to be written? Thanks. --shiv--

6

General Discussion / Typo in manual

« on: March 06, 2017, 03:43:13 AM »

I just started trying c2 and I ran into an error in the manual. In "My First Project" it suggests using the following as recipe.txt
target hello
  $warnings no-unused
  $generate-c
  hello.c2
end
However c2c complains that "Error: recipe: line 1 expected keyword executable|lib". Replacing "target" by "executable" did the trick for me.
--shiv--

7

General Discussion / Diffs to C99 and C11

« on: February 15, 2017, 06:43:38 PM »

I have tried reading through the documentation carefully but I cannot find out what are the precise "evolutions/omissions" over existing standards.

I know that there seems to be discussions about C-style macros. Will the _Generic macro, or something equivalent, be supported? These are quite essential for numerical codes that seek to re-use code over single, double, single complex and double complex numbers. More generically, if macros and #include's are removed, will some other facility be provided for generic programming?

Also, will variable length arrays and multi-dimensional arrays be supported?

Finally, this is outside the standard, what about OpenMP directives?

Thanks.
--shiv--