Frank Saez Posts - Answer Overflow

Frank Saez

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MModular

•Created by Frank Saez on 8/15/2024 in #community-showcase

LibCurl

Hi, https://github.com/f-saez/libcurl-mojo

1 replies

MModular

•Created by Frank Saez on 7/31/2024 in #community-showcase

HaldClut

Hi, I've created a (small) HaldClut library. https://github.com/f-saez/haldclut-mojo

2 replies

MModular

•Created by Frank Saez on 7/25/2024 in #community-showcase

boxblur

Hi, I've created a boxblur filter. In itself, it's more a demo or a tutorial than a useful piece of code. I've just wanted to put that code alone for toying with before using it elsewhere. https://github.com/f-saez/box_blur_mojo Nothing fancy but it may be useful for a beginner (convolution + a bit of SIMD + multi-threading)

1 replies

MModular

•Created by Frank Saez on 7/9/2024 in #community-showcase

Blend2D

Hi, The FFI for Blend2D, a 2D vector graphics engine. https://github.com/f-saez/blend2d-mojo

1 replies

MModular

•Created by Frank Saez on 7/1/2024 in #community-showcase

ZSTD

Hi, https://github.com/f-saez/zstd-mojo Same thing as LZ4 but with ZSTD.

1 replies

MModular

•Created by Frank Saez on 6/30/2024 in #community-showcase

LZ4

Hi, https://github.com/f-saez/lz4-mojo Basic FFI of LZ4, meaning just block compress/decompress ... for now.

1 replies

MModular

•Created by Frank Saez on 6/28/2024 in #community-showcase

LibJpeg

Hi, https://github.com/f-saez/libjpeg-mojo My little take on LibJpeg and FFI. It's just a toy right now, but it may grow in the future

1 replies

MModular

•Created by Frank Saez on 6/14/2024 in #questions

About lifetimes

Hi, I'm playing with FFI and I need to know how to manage correctly some lifetimes. Let's take an example :

alias external_func = fn(UnsafePointer[JpegErrorMgr]) -> UInt

@value
struct Stuff:
  var pointer : UnsafePointer[UInt8]
  var ... # many other fields

fn main():
  var thing = ffi.DLHandle("liblambda.so", ffi.RTLD.NOW)
  if thing.__bool__():
    var bytes = List[UInt8]()
    with open("file", "rb") as f:
      bytes = f.read_bytes()    

    var my_struct = Stuff()
    my_struct.pointer = bytes.unsafe_ptr()
    var result = thing.get_function[external_func]("external_func")(my_struct.unsafe_ptr()) 
    # others call to external_func but no other use of my_struct
    ...

alias external_func = fn(UnsafePointer[JpegErrorMgr]) -> UInt

@value
struct Stuff:
  var pointer : UnsafePointer[UInt8]
  var ... # many other fields

fn main():
  var thing = ffi.DLHandle("liblambda.so", ffi.RTLD.NOW)
  if thing.__bool__():
    var bytes = List[UInt8]()
    with open("file", "rb") as f:
      bytes = f.read_bytes()    

    var my_struct = Stuff()
    my_struct.pointer = bytes.unsafe_ptr()
    var result = thing.get_function[external_func]("external_func")(my_struct.unsafe_ptr()) 
    # others call to external_func but no other use of my_struct
    ...

If I understand correctly, for Mojo, the life of bytes stops as soon as my_struct is not used and in this case, it's just after the first call to "external_func". Trouble is external_func will need bytes to be alive for a longer time but Mojo can't know that and external_func will starts to act funny because the values of bytes may have changed So, my question is : how to manage this kind of lifetime ? an easy answer is to do some useless stuff with my_struct at the end of the block or encapsulate some parts in a function (it's what I do now), but a cleaner way to do that must exists. I've also try to use DTypePointer but I have only be able to use them with basic types like a bunch of bytes but not structured data I must have misunderstood something.

2 replies

MModular

•Created by Frank Saez on 6/12/2024 in #questions

FFI

Hi, I'm working on FFI and I've got two small questions : 1 - what is the equivalent of size_t in Mojo ? 2 - Dynamic linking is easy but I haven't found a way to proceed with a static library (.a file). Is there a clean and official way to do that ? Thanks.

16 replies

MModular

•Created by Frank Saez on 6/5/2024 in #questions

Question about iterating a list of strings

Hi, I've got a background in Rust (10 years) and in Python (1 year) and I try to learn Mojo. I've try this :

fn main():
  try:
    var stuff = String("dddd\nffff\njjjj\nkkkk").split("\n")
    for x in stuff:
      print(x)
  except:
    print("failed")

fn main():
  try:
    var stuff = String("dddd\nffff\njjjj\nkkkk").split("\n")
    for x in stuff:
      print(x)
  except:
    print("failed")

and got this obscure error message :

/source/prog.mojo:7:12: error: no matching function in call to 'print'
      print(x)
      ~~~~~^~~
/source/prog.mojo:1:1: note: candidate not viable: expected at most 0 positional arguments, got 1
fn main():
^
/source/prog.mojo:1:1: note: candidate not viable: callee expects 2 parameters, but 0 were specified
fn main():
^
/source/prog.mojo:7:13: note: failed to infer parameter 'T', argument type 'Reference[String, 1, stuff, 0]' does not conform to trait 'Stringable'
      print(x)
            ^
mojo: error: failed to parse the provided Mojo source module

/source/prog.mojo:7:12: error: no matching function in call to 'print'
      print(x)
      ~~~~~^~~
/source/prog.mojo:1:1: note: candidate not viable: expected at most 0 positional arguments, got 1
fn main():
^
/source/prog.mojo:1:1: note: candidate not viable: callee expects 2 parameters, but 0 were specified
fn main():
^
/source/prog.mojo:7:13: note: failed to infer parameter 'T', argument type 'Reference[String, 1, stuff, 0]' does not conform to trait 'Stringable'
      print(x)
            ^
mojo: error: failed to parse the provided Mojo source module

but if I use indexes, it works :

for x in range(0, len(stuff)):
      print(stuff[x])

for x in range(0, len(stuff)):
      print(stuff[x])

I seem to have a hard time with the most basic things 🙂 What have I misunderstood ? Thanks

14 replies

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