Re: Two questions regarding 'native'

[Alexander Williams]

This looks pretty good.

If it helps, I've written a few 'native' tutorials, at 
https://picolisp.a1w.ca


+1 for choosing a liberal license as well (CC0).


AW

On 17-10-24 11:06 AM, Alfonso Villén wrote:


I've created a public Bitbucket repository with my work so far,
including some examples.
https://bitbucket.org/alfonsovillen/picolispffi


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Re: Two questions regarding 'native'

[Alfonso Villén]

Hello Mike,

I've just made the Reddit post:
https://www.reddit.com/r/lisp/comments/78iy7w/sdl2_and_opengl_33_on_picolisp_64bit/

2017-10-24 13:35 GMT+02:00 Mike Pechkin :

> ​Alfonso,
>
> Make a post on reddit.com/r/lisp​
>
>
>
>
>> I've created a public Bitbucket repository with my work so far, including
>> some examples.
>> https://bitbucket.org/alfonsovillen/picolispffi
>>
>> I don't know if someone will be interested in it, but I'm having fun
>> doing it.
>>
>
>

Re: Two questions regarding 'native'

[Mike Pechkin]

​Alfonso,

Make a post on reddit.com/r/lisp​




> I've created a public Bitbucket repository with my work so far, including
> some examples.
> https://bitbucket.org/alfonsovillen/picolispffi
>
> I don't know if someone will be interested in it, but I'm having fun doing
> it.
>

Re: Two questions regarding 'native'

[Alfonso Villén]

Hello,

finally, I could display a triangle using OpenGL 3.3. I translated the code
from the C tutorial at:
https://learnopengl.com/#!Getting-started/Hello-Triangle.

Thanks again for your help, Alex.

Unfortunately I'm running into difficulties again because after translating
the next tutorial, nothing is rendered. Maybe I'll post a question about it
later.

I've created a public Bitbucket repository with my work so far, including
some examples.
https://bitbucket.org/alfonsovillen/picolispffi

I don't know if someone will be interested in it, but I'm having fun doing
it.

Bye,
Alfonso V.

2017-10-21 15:34 GMT+02:00 Alexander Burger :

> On Sat, Oct 21, 2017 at 02:38:18PM +0200, Alfonso Villén wrote:
> > The function arguments don't work as you expected. That C function needs
> > some weird information such as an array of integers giving the length of
> > the strings in the other array if those don't end with null bytes...
>
> Ah, I see. Didn't know that. Then it is probably something like:
>
>
>(de glShaderSource (Shader Strings)
>   (let
>  (Lst
> (mapcar
>'((Str) (cons (native "@" "strdup" 'N Str) 8))
>Strings )
> Len (length Strings) )
>  (native `*GlutLib "glShaderSource" NIL
> Shader
> Len
> (cons NIL (list (* 8 Len)) Lst)
> (cons NIL (list (* 8 Len))
>(mapcar
>   '((Str) (- (length Str)))
>   Strings ) ) )
>  (mapc '((X) (native "@" "free" NIL (car X))) Lst) ) )
>
>
> > I'm also having problems with other function, and in all of them there
> are
> > pointer arguments involved. But I hope I'll be able to figure the
> solution
> > myself.
> >
> > When I get some examples working I'd like to share the code with you all.
>
> Great, thanks! Perhaps we can add them to @lib/openGl.l then.
>
> ♪♫ Alex
>
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>

Re: Two questions regarding 'native'

[Alexander Burger]

On Sat, Oct 21, 2017 at 02:38:18PM +0200, Alfonso Villén wrote:
> The function arguments don't work as you expected. That C function needs
> some weird information such as an array of integers giving the length of
> the strings in the other array if those don't end with null bytes...

Ah, I see. Didn't know that. Then it is probably something like:


   (de glShaderSource (Shader Strings)
  (let
 (Lst
(mapcar
   '((Str) (cons (native "@" "strdup" 'N Str) 8))
   Strings )
Len (length Strings) )
 (native `*GlutLib "glShaderSource" NIL
Shader
Len
(cons NIL (list (* 8 Len)) Lst)
(cons NIL (list (* 8 Len))
   (mapcar
  '((Str) (- (length Str)))
  Strings ) ) )
 (mapc '((X) (native "@" "free" NIL (car X))) Lst) ) )


> I'm also having problems with other function, and in all of them there are
> pointer arguments involved. But I hope I'll be able to figure the solution
> myself.
> 
> When I get some examples working I'd like to share the code with you all.

Great, thanks! Perhaps we can add them to @lib/openGl.l then.

♪♫ Alex

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Re: Two questions regarding 'native'

[Alfonso Villén]

Hello,

thank you very much, Alex. It seems to work, but I have to test more
thoroughly.

The function arguments don't work as you expected. That C function needs
some weird information such as an array of integers giving the length of
the strings in the other array if those don't end with null bytes...

I'm also having problems with other function, and in all of them there are
pointer arguments involved. But I hope I'll be able to figure the solution
myself.

When I get some examples working I'd like to share the code with you all.

Alfonso Villén

Am 21.10.2017 10:08 schrieb "Alexander Burger" :

> Hi Alfonso,
>
> > I'm exploring Picolisp as a hobby for a while now, and I find it
> absolutely
> > amazing. I'm experimenting with 'native', trying to make some bindings
> for
> > SDL2 and OpenGL.
>
> I assume you found the OpenGL library in the distribution too, right? Just
> for
> the records, it is in "@lib/openGl.l".
>
>
> > I want to call this OpenGL function with 'native':
> >
> > void glShaderSource(
> > GLuint shader,
> > GLsizei count,
> > const GLchar **string,
> > const GLint *length)
> >
> > I have a problem with the third argument. I can't figure out if and how a
> > pointer to an array of string pointers can be passed to the function
> using
> > 'native'.
>
> An array of string pointers basically boils down to a structure in C.
>
> However, this case is indeed tricky, because the string array must first be
> created. I would call strdup() to get a list of pointers.
>
> Assuming you have {"abc", "def", "ghi"), this would be
>
>(mapcar
>   '((Str) (cons (native "@" "strdup" 'N Str) 8))
>   '("abc" "def" "ghi") )
>
> That is, it creates a list (( . 8) ( . 8) ( .
> 8)).
> The '8' values are needed for the 'native' struct definition (as the
> reference
> says "a pair (num . cnt) where 'num' is stored in a field of 'cnt' bytes").
>
> Note that you must also call free() on the results of strdup() when done.
>
>
> > My other question is about the fourth argument. Is there a way (other
> than
> > allocating some memory with 'malloc') so you can pass a C pointer to a
> > Picolisp symbol's value using 'native'?
>
> You can pass a pointer simply as a number. But this doesn't make sense
> here,
> because where should that pointer come from?
>
> So one way is to call 'malloc' as you said, but you can better let
> 'native' do
> the alloction for you, as another structure which holds a single pointer
> and
> which returns its value. The following passes the number 3 in a
> single-element
> 'int' array, receiving the possibly modified value in the variable 'Len':
>
>(Len (8 . I) -3)
>
> If you are not interested in a return value, and just want to pass 3:
>
>(NIL (8) -3)
>
>
> With all that, your function would be:
>
>(de glShaderSource (Shader Count Strings)
>   (let
>  (Lst
> (mapcar
>'((Str) (cons (native "@" "strdup" 'N Str) 8))
>Strings )
> Len (length Lst) )
>  (native `*GlutLib "glShaderSource" NIL
> Shader
> Count
> (cons NIL (list (* 8 Len)) Lst)
> (list 'Len (8 . I) (- Len)) )
>  (mapc '((X) (native "@" "free" NIL (car X))) Lst)
>  Len ) )
>
> You call it as (glShaderSource 3 4 '("abc" "def" "ghi")).
>
> I haven't checked the OpenGL docs if this makes sense, and haven't tested
> the
> above. It assumes that 'length' holds the number of strings in 'string'
> (and not
> 'count'!). And it assumes that you want to return the length in 'Len'. So
> the
> above must perhaps be modified.
>
> Indeed rather messy ;)
>
> ♪♫ Alex
>
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Re: Two questions regarding 'native'

[Alexander Burger]

Hi Alfonso,

> I'm exploring Picolisp as a hobby for a while now, and I find it absolutely
> amazing. I'm experimenting with 'native', trying to make some bindings for
> SDL2 and OpenGL.

I assume you found the OpenGL library in the distribution too, right? Just for
the records, it is in "@lib/openGl.l".


> I want to call this OpenGL function with 'native':
> 
> void glShaderSource(
> GLuint shader,
> GLsizei count,
> const GLchar **string,
> const GLint *length)
> 
> I have a problem with the third argument. I can't figure out if and how a
> pointer to an array of string pointers can be passed to the function using
> 'native'.

An array of string pointers basically boils down to a structure in C.

However, this case is indeed tricky, because the string array must first be
created. I would call strdup() to get a list of pointers.

Assuming you have {"abc", "def", "ghi"), this would be

   (mapcar
  '((Str) (cons (native "@" "strdup" 'N Str) 8))
  '("abc" "def" "ghi") )

That is, it creates a list (( . 8) ( . 8) ( . 8)).
The '8' values are needed for the 'native' struct definition (as the reference
says "a pair (num . cnt) where 'num' is stored in a field of 'cnt' bytes").

Note that you must also call free() on the results of strdup() when done.


> My other question is about the fourth argument. Is there a way (other than
> allocating some memory with 'malloc') so you can pass a C pointer to a
> Picolisp symbol's value using 'native'?

You can pass a pointer simply as a number. But this doesn't make sense here,
because where should that pointer come from?

So one way is to call 'malloc' as you said, but you can better let 'native' do
the alloction for you, as another structure which holds a single pointer and
which returns its value. The following passes the number 3 in a single-element
'int' array, receiving the possibly modified value in the variable 'Len':

   (Len (8 . I) -3)

If you are not interested in a return value, and just want to pass 3:

   (NIL (8) -3)


With all that, your function would be:

   (de glShaderSource (Shader Count Strings)
  (let
 (Lst
(mapcar
   '((Str) (cons (native "@" "strdup" 'N Str) 8))
   Strings )
Len (length Lst) )
 (native `*GlutLib "glShaderSource" NIL
Shader
Count
(cons NIL (list (* 8 Len)) Lst)
(list 'Len (8 . I) (- Len)) )
 (mapc '((X) (native "@" "free" NIL (car X))) Lst)
 Len ) )

You call it as (glShaderSource 3 4 '("abc" "def" "ghi")).

I haven't checked the OpenGL docs if this makes sense, and haven't tested the
above. It assumes that 'length' holds the number of strings in 'string' (and not
'count'!). And it assumes that you want to return the length in 'Len'. So the
above must perhaps be modified.

Indeed rather messy ;)

♪♫ Alex

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Two questions regarding 'native'

[Alfonso Villén]

Hello,

I'm exploring Picolisp as a hobby for a while now, and I find it absolutely
amazing. I'm experimenting with 'native', trying to make some bindings for
SDL2 and OpenGL.

I want to call this OpenGL function with 'native':

void glShaderSource(
GLuint shader,
GLsizei count,
const GLchar **string,
const GLint *length)

I have a problem with the third argument. I can't figure out if and how a
pointer to an array of string pointers can be passed to the function using
'native'.

My other question is about the fourth argument. Is there a way (other than
allocating some memory with 'malloc') so you can pass a C pointer to a
Picolisp symbol's value using 'native'?

I'd be very glad if someone could answer.

Alfonso Villén