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Forum => newLISP in the real world => Topic started by: AVC on January 11, 2022, 02:18:15 PM

Title: Bug in struct with float arguments?
Post by: AVC on January 11, 2022, 02:18:15 PM
Hello,



I love newLISP and I'm trying to use it for some graphics programming. So I'm writing a FFI module for the raylib library.



I've encountered an odd behavior of struct: If I define a 'struct' with one or more floats and pass it to 'pack', the float values are stored as zeroes. But surprisingly the same struct works well with 'unpack'. Here is an example:



(struct 'Vector2 "float" "float")

(pack Vector2 200 200) => returns "0000000000000000", which is wrong!

(pack "ff" 200 200) => returns "0000HC0000HC", which is what 'pack Vector2...' also should return

(unpack Vector2 (pack "ff" 200 200)) => returns (200 200) correctly!



I'm using newLISP 10.7.5 64-bit on Arch Linux with ffi and UTF-8 support enabled.



Is there a bug or am I doing something wrong?



Thanks in advance

Alfonso
Title: Re: Bug in struct with float arguments?
Post by: rrq on January 15, 2022, 01:01:29 AM
Yes it's a bug in the handling of the "incoming cell data" for an ffi_type_float at nl-import.c:814.

That current line is
Code Select
floatV = (float) *(double *)&cell->aux;
and should be replaced with the following
Code Select
floatV = (float) ((cell->type == CELL_FLOAT)? *(double *)&uint64V : uint64V);
which corresponds to how it's handled in the pack function.
Title: Re: Bug in struct with float arguments?
Post by: AVC on January 16, 2022, 08:36:58 AM
I've changed that line and recompiled. Bug solved! Thank you very much!
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